XR88C681CJ [EXAR]
CMOS DUAL CHANNEL UART (DUART); CMOS双通道UART （ DUART ）
| 型号： | XR88C681CJ |
| 厂家： | 
EXAR CORPORATION |
| 描述： | CMOS DUAL CHANNEL UART (DUART) |
| 文件： | 总99页 (文件大小：1906K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
XR88C681
ꢀꢁꢂꢃ ꢄꢅꢆꢇ ꢀꢈꢆꢉꢉꢊꢇ
ꢋꢌꢍꢎ ꢏꢄꢋꢌꢍꢎꢐ
ꢃꢊꢗꢘꢊꢙꢚꢊꢛ ꢔꢖꢖꢖꢜꢓ
FEATURES
ꢁ ꢎꢝꢞ ꢅꢇꢇ ꢄꢅꢗꢇꢊ!" #ꢉ$ꢊꢗꢊꢉ$ꢊꢉꢘ ꢀꢈꢆꢉꢉꢊꢇ%
ꢁ ꢌ%&ꢉ'ꢈꢛꢞꢉꢞꢅ% ꢍꢊ'ꢊ(ꢑꢊꢛ ꢆꢉ$ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ
ꢁ )ꢅꢆ$ꢛꢅꢗꢇꢊꢜ*ꢅ++ꢊꢛꢊ$ ꢍꢊ'ꢊ(ꢑꢊꢛ% ꢆꢉ$ ꢄꢅꢆꢇ *ꢅ++ꢊꢛꢊ$
ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ%
ꢁ ,ꢛꢞ-ꢛꢆꢙꢙꢆꢚꢇꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢄꢆ(%& ꢀꢈꢆ(ꢉ
ꢁ = 0ꢊꢉꢊꢛꢆꢇ ,ꢅꢛꢗꢞ%ꢊ ꢂꢅꢘꢗꢅꢘ% ꢏ<ꢕ ,(ꢉ ꢄ#, ꢆꢉ$ << ,(ꢉ
,9ꢀꢀ ,ꢆ'3ꢆ-ꢊ% ꢂꢉꢇ&ꢐ
ꢁ > 0ꢊꢉꢊꢛꢆꢇ ,ꢅꢛꢗꢞ%ꢊ #ꢉꢗꢅꢘ% ꢝ(ꢘꢈ ꢀꢈꢆꢉ-ꢊ ꢞ+ ꢃꢘꢆꢘꢊ%
ꢄꢊꢘꢊ'ꢘꢞꢛ% ꢞꢉ #ꢉꢗꢅꢘ% ꢏ<ꢕ ,(ꢉ ꢄ#, ꢆꢉ$ << ,(ꢉ ,9ꢀꢀ
,ꢆ'3ꢆ-ꢊ% ꢂꢉꢇ&ꢐ
ꢁ ,ꢛꢞ-ꢛꢆꢙꢙꢆꢚꢇꢊ ꢃꢘꢞꢗ *(ꢘ% (ꢉ ꢔ.ꢔ/ *(ꢘ #ꢉ'ꢛꢊꢙꢊꢉꢘ%
ꢁ #ꢉꢘꢊꢛꢉꢆꢇ *(ꢘ ꢍꢆꢘꢊ 0ꢊꢉꢊꢛꢆꢘꢞꢛ% ꢝ(ꢘꢈ ꢁꢞꢛꢊ ꢘꢈꢆꢉ ꢓ1 *(ꢘ
ꢍꢆꢘꢊ%
ꢁ ꢁꢅꢇꢘ(ꢜꢄꢛꢞꢗ ꢁꢞ$ꢊ ꢀꢞꢙꢗꢆꢘ(ꢚꢇꢊ ꢝ(ꢘꢈ =ꢕ6ꢔ 7(ꢉꢊ *(ꢘ
ꢁꢞ$ꢊ
ꢁ ꢂꢉꢜꢀꢈ(ꢗ ꢂ%'(ꢇꢇꢆꢘꢞꢛ +ꢞꢛ ꢀꢛ&%ꢘꢆꢇ
ꢁ #ꢉ$ꢊꢗꢊꢉ$ꢊꢉꢘ *(ꢘ ꢍꢆꢘꢊ ꢃꢊꢇꢊ'ꢘ(ꢞꢉ +ꢞꢛ 2ꢆ'ꢈ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ
ꢆꢉ$ ꢍꢊ'ꢊ(ꢑꢊꢛ
ꢁ 2!ꢘꢊꢛꢉꢆꢇ ꢀꢇꢞ'3 ꢀꢆꢗꢆꢚ(ꢇ(ꢘ&
ꢁ ꢃꢘꢆꢉ$ꢚ& ꢁꢞ$ꢊ ꢘꢞ ꢍꢊ$ꢅ'ꢊ ꢂꢗꢊꢛꢆꢘ(ꢉ- ,ꢞꢝꢊꢛ
ꢁ ꢀꢞꢙꢗꢆꢘ(ꢚꢇꢊ ꢝ(ꢘꢈ ꢘꢈꢊ ꢁꢞꢘꢞꢛꢞꢇꢆ ꢁꢀꢓ/=ꢔ ꢆꢉ$
ꢃ(-ꢉꢊꢘ('% ꢃꢀꢀꢓ/ꢖꢓ $ꢊꢑ('ꢊ%
ꢁ ꢁꢆ!(ꢙꢅꢙ *(ꢘ ꢍꢆꢘꢊ4 ꢔ5 ꢀꢇꢞ'3 ꢜ ꢔꢁꢚ.%" ꢔ/5 ꢀꢇꢞ'3 ꢜ
ꢔꢓ63ꢚ.%
ꢁ ꢌ$ꢑꢆꢉ'ꢊ$ ꢀꢁꢂꢃ 9ꢞꢝ ,ꢞꢝꢊꢛ ꢎꢊ'ꢈꢉꢞꢇꢞ-&
ꢁ 7ꢞꢛꢙꢆꢇ" ꢌꢋꢎꢂ2ꢀ8ꢂ" 9ꢞ'ꢆꢇ 9ꢂꢂ,*ꢌꢀ: ꢆꢉ$
ꢍꢊꢙꢞꢘꢊ 9ꢂꢂ,*ꢌꢀ: ꢁꢞ$ꢊ%
APPLICATIONS
ꢁ ꢁꢅꢇꢘ(ꢜ+ꢅꢉ'ꢘ(ꢞꢉ ꢔ/ *(ꢘ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ
ꢁ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢂꢅꢘꢗꢅꢘ ꢝ(ꢘꢈ 2(-ꢈꢘ ꢁꢆ%3ꢆꢚꢇꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢀꢞꢉ$(ꢘ(ꢞꢉ%
ꢁ ꢁꢅꢇꢘ(ꢙꢊ$(ꢆ ꢃ&%ꢘꢊꢙ%
ꢁ ꢃꢊꢛ(ꢆꢇ ꢘꢞ ,ꢆꢛꢆꢇꢇꢊꢇ.,ꢆꢛꢆꢇꢇꢊꢇ ꢘꢞ ꢃꢊꢛ(ꢆꢇ ꢀꢞꢉꢑꢊꢛꢘꢊꢛ
ꢁ ꢄꢎ2 +ꢞꢛ ꢁꢞ$ꢊꢙ ꢀꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉ ꢃ&%ꢘꢊꢙ%
ꢁ #ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ ꢂꢅꢘꢗꢅꢘ ꢞꢉ ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊ ꢏ<ꢕ ,(ꢉ ꢄ#,
ꢆꢉ$ << ,(ꢉ ,9ꢀꢀ ,ꢆ'3ꢆ-ꢊ% ꢂꢉꢇ&ꢐ
GENERAL DESCRIPTION
ꢎꢈꢊ 25ꢌꢍ ꢄꢅꢆꢇ ꢋꢉ(ꢑꢊꢛ%ꢆꢇ ꢌ%&ꢉ'ꢈꢛꢞꢉꢞꢅ% ꢍꢊ'ꢊ(ꢑꢊꢛ ꢆꢉ$
ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢏꢄꢋꢌꢍꢎꢐ (% ꢆ $ꢆꢘꢆ 'ꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉ% $ꢊꢑ('ꢊ ꢘꢈꢆꢘ
ꢗꢛꢞꢑ($ꢊ% ꢘꢝꢞ +ꢅꢇꢇ& (ꢉ$ꢊꢗꢊꢉ$ꢊꢉꢘ +ꢅꢇꢇ $ꢅꢗꢇꢊ! ꢆ%&ꢉ'ꢈꢛꢞꢉꢞꢅ%
'ꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉ 'ꢈꢆꢉꢉꢊꢇ% (ꢉ ꢆ %(ꢉ-ꢇꢊ ꢗꢆ'3ꢆ-ꢊꢒ ꢎꢈꢊ ꢄꢋꢌꢍꢎ
(% $ꢊ%(-ꢉꢊ$ +ꢞꢛ ꢅ%ꢊ (ꢉ ꢙ('ꢛꢞꢗꢛꢞ'ꢊ%%ꢞꢛ ꢚꢆ%ꢊ$ %&%ꢘꢊꢙ% ꢆꢉ$
ꢙꢆ& ꢚꢊ ꢅ%ꢊ$ (ꢉ ꢆ ꢗꢞꢇꢇꢊ$ ꢞꢛ (ꢉꢘꢊꢛꢛꢅꢗꢘ $ꢛ(ꢑꢊꢉ ꢊꢉꢑ(ꢛꢞꢉꢙꢊꢉꢘꢒ
ꢎꢈꢊ ꢄꢋꢌꢍꢎ (% +ꢆꢚꢛ('ꢆꢘꢊ$ ꢅ%(ꢉ- ꢆ$ꢑꢆꢉ'ꢊ$ ꢘꢝꢞ ꢇꢆ&ꢊꢛ ꢙꢊꢘꢆꢇ"
ꢝ(ꢘꢈ ꢆ ꢈ(-ꢈ ꢗꢊꢛ+ꢞꢛꢙꢆꢉ'ꢊ $ꢊꢉ%(ꢘ& 2,#.ꢀꢁꢂꢃ ꢔꢒ=• ꢗꢛꢞ'ꢊ%%
ꢘꢞ ꢗꢛꢞꢑ($ꢊ ꢈ(-ꢈ ꢗꢊꢛ+ꢞꢛꢙꢆꢉ'ꢊ ꢆꢉ$ ꢇꢞꢝ ꢗꢞꢝꢊꢛ 'ꢞꢉ%ꢅꢙꢗꢘ(ꢞꢉ"
ꢆꢉ$ (% ꢗꢆ'3ꢆ-ꢊ$ (ꢉ ꢆ <ꢕ ꢗ(ꢉ ,ꢄ#," ꢆ ꢓ= ꢗ(ꢉ ,ꢄ#," ꢆꢉ$ ꢆ <<
ꢗ(ꢉ ,9ꢀꢀꢒ
ꢎꢈꢊ 5ꢍ==ꢀ/=ꢔ $ꢊꢑ('ꢊ ꢞ++ꢊꢛ% ꢆ %(ꢉ-ꢇꢊ #ꢀ %ꢞꢇꢅꢘ(ꢞꢉ +ꢞꢛ ꢘꢈꢊ
=ꢕ=ꢕ.=6" =ꢕ=/.==" ?=ꢕ" ?=ꢕꢕꢕ" /=!! ꢆꢉ$ /6!!
ꢙ('ꢛꢞꢗꢛꢞ'ꢊ%%ꢞꢛ +ꢆꢙ(ꢇ(ꢊ%ꢒ
ORDERING INFORMATION
Operating
Temperature Range
Part No.
Pin Package
<< ,9ꢀꢀ
5ꢍ==ꢀ/=ꢔꢀ@
5ꢍ==ꢀ/=ꢔꢀ7.<ꢕ
5ꢍ==ꢀ/=ꢔꢀ,.ꢓ=
5ꢍ==ꢀ/=ꢔꢀ,.<ꢕ
5ꢍ==ꢀ/=ꢔ@
ꢕꢀꢀ ꢘꢞ >ꢕꢀꢀ
ꢕꢀꢀ ꢘꢞ >ꢕꢀꢀ
<ꢕ ꢀꢄ#,
ꢓ= ,ꢄ#,
<ꢕ ,ꢄ#,
<< ,9ꢀꢀ
<ꢕ ꢀꢄ#,
ꢓ= ,ꢄ#,
<ꢕ ,ꢄ#,
ꢕꢀꢀ ꢘꢞ >ꢕꢀꢀ
ꢕꢀꢀ ꢘꢞ >ꢕꢀꢀ
ꢜ<ꢕꢀꢀ ꢘꢞ A=6ꢀꢀ
ꢜ<ꢕꢀꢀ ꢘꢞ A=6ꢀꢀ
ꢜ<ꢕꢀꢀ ꢘꢞ A=6ꢀꢀ
ꢜ<ꢕꢀꢀ ꢘꢞ A=6ꢀꢀ
5ꢍ==ꢀ/=ꢔ7.<ꢕ
5ꢍ==ꢀ/=ꢔ,.ꢓ=
5ꢍ==ꢀ/=ꢔ,.<ꢕ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢀꢔꢖꢖꢖ
XR88C681
ꢎ5ꢄꢌ
ꢍ5ꢄꢌ
ꢎ5ꢄ*
ꢍ5ꢄ*
#,ꢕ ꢜ #,/
ꢂ,ꢕ ꢜ ꢂ,>
ꢎꢃꢍ
ꢎ8ꢍ
ꢍꢃꢍ
ꢍ8ꢍ
ꢎꢃꢍ
ꢎ8ꢍ
ꢍꢃꢍ
ꢍ8ꢍ
#,ꢍ
ꢂ,ꢍ
ꢀꢈꢆꢉ-ꢊ ꢞ+
ꢃꢘꢆꢘꢊ ꢄꢊꢘꢊ'ꢘꢞꢛ%
ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ
ꢅꢉ'ꢘ(ꢞꢉ ꢃꢊꢇꢊ'ꢘ
9ꢞ-('
#,ꢀꢍ
ꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛ%
ꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛ%
ꢂ,ꢀꢍ
ꢌꢀꢍ
ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ
ꢀꢈꢆꢉꢉꢊꢇ ꢌ
ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ
ꢀꢈꢆꢉꢉꢊꢇ *
#ꢉꢗꢅꢘ ,ꢞꢛꢘ
ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ
#ꢉꢘꢊꢛꢉꢆꢇ ꢄꢆꢘꢆ *ꢅ%
ꢂꢗꢊꢛꢆꢘ(ꢞꢉ ꢀꢞꢉꢘꢛꢞꢇ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢀꢞꢉꢘꢛꢞꢇ
ꢎ(ꢙ(ꢉ-
ꢀꢃꢍꢌ
ꢀꢃꢍ*
#;ꢍ
ꢁ#ꢃꢍ
#ꢁꢍ
#ꢃꢍ
ꢀꢍ*
ꢀꢍꢌ
*(ꢘ ꢍꢆꢘꢊ
0ꢊꢉꢊꢛꢆꢘꢞꢛ
ꢄꢆꢘꢆ
*ꢅ%
ꢌ$$ꢛꢊ%% ꢄꢊ'ꢞ$ꢊꢛ
*ꢅ++ꢊꢛ
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ
ꢂ%'(ꢇꢇꢆꢘꢞꢛ
ꢄꢕ ꢜ ꢄ> ꢌꢕ ꢜ ꢌ1
ꢜꢍꢄ ꢜBꢍ ꢜꢀꢃ ꢍ2ꢃ2ꢎ
#2# #2ꢂ ꢜ#ꢌꢀ: ꢜ#7ꢎꢍ
5ꢔ.ꢀ9: 5ꢓ
Figure 1. Block Diagram of the XR88C681
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢓ
XR88C681
PIN CONFIGURATION
ꢌꢕ
#,1
;
ꢔ
ꢓ
<ꢕ
ꢀꢀ
1ꢖ #,<.#2#
ꢌꢔ
#,6.#2ꢂ
1
1=
#,ꢔ
ꢜ#,/.#ꢌꢀ:
<
1>
ꢌꢓ
#,ꢓ
6
1/
ꢌ1
>
1ꢖ
1=
ꢀꢃ
ꢌ1
ꢜꢀꢃ
/
16
#,ꢕ
ꢜBꢍ
=
ꢖ
ꢜꢍ2ꢃ2ꢎ
#,ꢕ
ꢍ2ꢃ2ꢎ
>
1<
1> 5ꢓ
ꢜBꢍ
ꢜꢍꢄ
ꢍ5ꢄ*
5ꢓ
=
11
ꢜꢍꢄ
ꢔꢕ
1/
16
1<
11
1ꢓ
1ꢔ
5ꢔ.ꢀ9:
ꢍ5ꢄꢌ
5ꢔ.ꢀ9:
ꢖ
1ꢓ
ꢍ5ꢄ*
7ꢀ
ꢔꢔ
ꢔꢓ
ꢔ1
ꢔ<
ꢔ6
ꢔ/
ꢍ5ꢄꢌ
ꢔꢕ
ꢔꢔ
ꢔꢓ
ꢔ1
1ꢔ
XR-68C681CJ
PLCC
7ꢀ
1ꢕ
ꢎ5ꢄ*
ꢂ,ꢔ
ꢎ5ꢄꢌ
ꢎ5ꢄ*
ꢎ5ꢄꢌ
ꢂ,ꢕ
ꢂ,ꢓ
ꢂ,<
ꢂ,/
ꢓꢖ
ꢂ,ꢕ
ꢂ,ꢔ
ꢂ,1
ꢂ,6
ꢓ=
ꢂ,1
ꢂ,ꢓ
ꢂ,6 ꢔ<
ꢓ> ꢂ,<
1ꢕ
ꢓꢖ
ꢂ,>
ꢂ,/
ꢔ6
ꢓ/
ꢂ,> ꢔ>
ꢔ/
ꢓ6
ꢄꢔ
ꢄꢕ
ꢄ1 ꢔ>
ꢓ< ꢄꢓ
ꢄ6
ꢄ<
ꢔ=
ꢓ1
ꢄ>
ꢄ/
ꢔꢖ
ꢓꢓ
07ꢄ
ꢜ#7ꢎꢍ
ꢓꢕ
ꢓꢔ
40 Lead PDIP, CDIP (0.600”)
44 Lead PLCC
7ꢀ
ꢌꢔ
ꢔ
ꢓ
ꢓ=
;
ꢀꢀ
ꢓ> #,ꢓ
1
ꢓ/
ꢌꢓ
ꢌ1
ꢜꢀꢃ
<
ꢓ6
ꢍ2ꢃ2ꢎ
6
ꢓ<
ꢓ1
ꢓꢓ
ꢓꢔ
ꢓꢕ
ꢔꢖ
ꢔ=
ꢔ>
ꢔ/
ꢔ6
ꢜBꢍ
5ꢓ
/
ꢜꢍꢄ
ꢍ5ꢄ*
ꢎ5ꢄ*
ꢂ,ꢔ
ꢄꢔ
5ꢔ.ꢀ9:
ꢍ5ꢄꢌ
ꢎ5ꢄꢌ
ꢂ,ꢕ
ꢄꢕ
>
=
ꢖ
ꢔꢕ
ꢔꢔ
ꢔꢓ
ꢔ1
ꢔ<
ꢄ1
ꢄꢓ
ꢄ6
ꢄ<
ꢄ>
ꢄ/
07ꢄ
ꢜ#7ꢎꢍ
28 Lead PDIP (0.600”)
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
1
XR88C681
PIN DESCRIPTION
44 PLCC/
LCC
40 DIP,
CDP
28 DIP,
CDIP
Symbol
Type Description
No Connection.
ꢔ
ꢓ
7ꢀ
ꢌꢕ
ꢔ
ꢓ
ꢔ
#
LSB of Address Input. ꢎꢈ(% (ꢉꢗꢅꢘ" ꢆꢇꢞꢉ- ꢝ(ꢘꢈ ꢌ$$ꢛꢊ%% #ꢉꢗꢅꢘ%"
ꢌꢔ ꢜ ꢌ1 ꢆꢛꢊ ꢅ%ꢊ$ ꢘꢞ %ꢊꢇꢊ'ꢘ 'ꢊꢛꢘꢆ(ꢉ ꢛꢊ-(%ꢘꢊꢛ% ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢄꢋꢌꢍꢎ
$ꢊꢑ('ꢊ" $ꢅꢛ(ꢉ- ꢍ2ꢌꢄ ꢆꢉ$ Bꢍ#ꢎ2 ꢞꢗꢊꢛꢆꢘ(ꢞꢉ% ꢝ(ꢘꢈ ꢘꢈꢊ ꢀ,ꢋꢒ
1
#,1
ꢏꢎ5ꢀꢌ ꢜ #ꢐ
ꢏꢍ5ꢀꢌ ꢜ ?ꢐ
#
Input Port 3. 0ꢊꢉꢊꢛꢆꢇ ,ꢅꢛꢗꢞ%ꢊ #ꢉꢗꢅꢘ ꢜ Bꢈꢊꢉ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (%
ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ #ꢜꢙꢞ$ꢊ" ꢘꢈ(% (ꢉꢗꢅꢘ 'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ ꢅ%ꢊ$ ꢆ% ꢘꢈꢊ
ꢊ!ꢘꢊꢛꢉꢆꢇ 'ꢇꢞ'3 (ꢉꢗꢅꢘ +ꢞꢛ ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢏꢎ5ꢀꢌꢐꢒ
Bꢈꢊꢉ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊ" ꢘꢈ(% (ꢉꢗꢅꢘ 'ꢆꢉ
ꢚꢊ ꢅ%ꢊ$ ꢆ% ꢘꢈꢊ ꢊ!ꢘꢊꢛꢉꢆꢇ 'ꢇꢞ'3 (ꢉꢗꢅꢘ +ꢞꢛ ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢍꢊ'ꢊ(ꢑꢜ
ꢊꢛ ꢏꢍ5ꢀꢌꢐꢒ
<
6
1
<
ꢓ
ꢌꢔ
#
#
Address Input.
#,ꢔ
ꢏꢜꢀꢎꢃ*ꢐ
Input Port 1. 0ꢊꢉꢊꢛꢆꢇ ,ꢅꢛꢗꢞ%ꢊ #ꢉꢗꢅꢘ ꢜ ꢎꢈ(% (ꢉꢗꢅꢘ 'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ
ꢅ%ꢊ$ ꢆ% ꢘꢈꢊ ꢌ'ꢘ(ꢑꢊ 9ꢞꢝ" Cꢀꢈꢆꢉꢉꢊꢇ * ꢀꢇꢊꢆꢛ ꢘꢞ ꢃꢊꢉ$D (ꢉꢗꢅꢘꢒ
ꢏꢜꢀꢎꢃ*ꢐ
/
>
6
/
1
<
ꢌꢓ
ꢌ1
#
#
Address Input.
MSB of Address Input. ꢎꢈ(% (ꢉꢗꢅꢘ" ꢆꢇꢞꢉ- ꢝ(ꢘꢈ ꢌ$$ꢛꢊ%% #ꢉꢜ
ꢗꢅꢘ%" ꢌꢕ ꢜ ꢌꢓ ꢆꢛꢊ ꢅ%ꢊ$ ꢘꢞ %ꢊꢇꢊ'ꢘ 'ꢊꢛꢘꢆ(ꢉ ꢛꢊ-(%ꢘꢊꢛ% ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ
ꢄꢋꢌꢍꢎ $ꢊꢑ('ꢊ" $ꢅꢛ(ꢉ- ꢍ2ꢌꢄ ꢆꢉ$ Bꢍ#ꢎ2 ꢞꢗꢊꢛꢆꢘ(ꢞꢉ% ꢝ(ꢘꢈ ꢘꢈꢊ
ꢀ,ꢋꢒ
=
ꢖ
>
=
#,ꢕ
ꢏꢜꢀꢎꢃꢌꢐ
#
#
Input 0. 0ꢊꢉꢊꢛꢆꢇ ,ꢅꢛꢗꢞ%ꢊ #ꢉꢗꢅꢘ ꢜ ꢎꢈ(% (ꢉꢗꢅꢘ 'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ ꢅ%ꢊ$
ꢆ% ꢘꢈꢊ ꢆ'ꢘ(ꢑꢊꢜꢇꢞꢝ" Cꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢀꢇꢊꢆꢛꢜꢘꢞꢜꢃꢊꢉ$D (ꢉꢗꢅꢘꢒ ꢏꢜꢀꢎꢃꢌꢐ
6
ꢜBꢍ
Write Strobe (Active-Low). ꢌ CꢇꢞꢝD ꢞꢉ ꢘꢈ(% (ꢉꢗꢅꢘ ꢝꢈ(ꢇꢊ ꢜꢀꢃ (%
ꢆꢇ%ꢞ CꢇꢞꢝD ꢝꢛ(ꢘꢊ% ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ% (ꢉꢘꢞ ꢘꢈꢊ ꢆ$ꢜ
$ꢛꢊ%%ꢊ$ ꢛꢊ-(%ꢘꢊꢛ" ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢄꢋꢌꢍꢎꢒ ꢎꢈꢊ ꢘꢛꢆꢉ%+ꢊꢛ ꢞ''ꢅꢛ% ꢞꢉ
ꢘꢈꢊ ꢛ(%(ꢉ- ꢊ$-ꢊ ꢞ+ ꢜBꢍꢒ
ꢔꢕ
ꢔꢔ
ꢖ
/
>
ꢜꢍꢄ
#
#
Read Strobe (Active Low). ꢌ CꢇꢞꢝD ꢞꢉ ꢘꢈ(% (ꢉꢗꢅꢘ ꢝꢈ(ꢇꢊ ꢜꢀꢃ (%
ꢆꢇ%ꢞ CꢇꢞꢝD ꢗꢇꢆ'ꢊ% ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ ꢆ$$ꢛꢊ%%ꢊ$ ꢄꢋꢌꢍꢎ ꢛꢊ-(%ꢜ
ꢘꢊꢛ" ꢞꢉ ꢘꢈꢊ $ꢆꢘꢆ ꢚꢅ%ꢒ
ꢔꢕ
ꢍ5ꢄ*
Receive Serial Data Input (Channel B). ꢎꢈꢊ ꢇꢊꢆ%ꢘ %(-ꢉ(+('ꢆꢉꢘ
ꢚ(ꢘ ꢞ+ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢛꢊ'ꢊ(ꢑꢊ$ +(ꢛ%ꢘꢒ #+ ꢊ!ꢘꢊꢛꢉꢆꢇ ꢛꢊ'ꢊ(ꢑꢊꢛ 'ꢇꢞ'3"
ꢍ5ꢀ*" (% %ꢗꢊ'(+(ꢊ$" ꢘꢈꢊ $ꢆꢘꢆ (% %ꢆꢙꢗꢇꢊ$ ꢞꢉ ꢘꢈꢊ ꢛ(%(ꢉ- ꢊ$-ꢊ ꢞ+
ꢘꢈ(% 'ꢇꢞ'3ꢒ
ꢔꢓ
ꢔ1
7ꢀ
No Connect.
ꢔꢔ
=
ꢎ5ꢄ*
ꢂ
Transmitter Serial Data Output (Channel B). ꢎꢈꢊ ꢇꢊꢆ%ꢘ %(-ꢜ
ꢉ(+('ꢆꢉꢘ ꢚ(ꢘ ꢞ+ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ +(ꢛ%ꢘꢒ ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ (%
ꢈꢊꢇ$ (ꢉ ꢘꢈꢊ ꢈ(-ꢈ ꢏꢙꢆꢛ3(ꢉ- %ꢘꢆꢘꢊꢐ ꢝꢈꢊꢉ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% ($ꢇꢊ"
$(%ꢆꢚꢇꢊ$" ꢞꢛ ꢝꢈꢊꢉ ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇ (% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ ꢇꢞ'ꢆꢇ 9ꢂꢂ,ꢜ
*ꢌꢀ: ꢙꢞ$ꢊꢒ #+ ꢆꢉ ꢊ!ꢘꢊꢛꢉꢆꢇ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ 'ꢇꢞ'3 (% %ꢗꢊ'(+(ꢊ$"
ꢎ5ꢀ*" ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ $ꢆꢘꢆ (% %ꢈ(+ꢘꢊ$ ꢞꢅꢘ ꢞ+ ꢘꢈꢊ ꢎꢃꢍ ꢏꢎꢛꢆꢉ%ꢜ
ꢙ(ꢘꢘꢊꢛ ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛꢐ ꢞꢉ ꢘꢈꢊ +ꢆꢇꢇ(ꢉ- ꢘꢈꢊ ꢊ$-ꢊ ꢞ+ ꢘꢈ(% 'ꢇꢞ'3ꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
<
XR88C681
44 PLCC/
LCC
40 DIP,
CDP
28 DIP,
CDIP
Symbol
Type
Description
ꢔ<
ꢔꢓ
ꢖ
ꢂ,ꢔ
ꢏꢜꢍꢎꢃ*ꢐ
ꢂ
Output 1 (General Purpose Output). ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ 'ꢆꢉ ꢆꢇ%ꢞ
ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢆ'ꢘ(ꢑꢊꢜꢇꢞꢝ" Cꢀꢈꢆꢉꢉꢊꢇ *
ꢍꢊEꢅꢊ%ꢘꢜꢘꢞꢜꢃꢊꢉ$D ꢂꢅꢘꢗꢅꢘ ꢏꢜꢍꢎꢃ*ꢐꢒ
ꢔ6
ꢔ1
ꢂ,1
ꢂ
Output 3 (General Purpose Output). ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ ꢗꢞꢛꢘ 'ꢆꢉ
ꢆꢇ%ꢞ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ%4 ꢘꢈꢊ Cꢀꢈꢆꢉꢉꢊꢇ * ꢎꢛꢆꢉ%ꢜ
ꢙ(ꢘꢘꢊꢛ ꢔ5 'ꢇꢞ'3D ꢞꢅꢘꢗꢅꢘ ꢏꢎ5ꢀ*Fꢔ5ꢐ" ꢘꢈꢊ Cꢀꢈꢆꢉꢉꢊꢇ * ꢍꢊ'ꢊ(ꢑꢜ
ꢊꢛ ꢔ5 'ꢇꢞ'3D ꢞꢅꢘꢗꢅꢘ ꢏꢍ5ꢀ*Fꢔ5ꢐ" ꢞꢛ ꢘꢈꢊ ꢞꢗꢊꢉ $ꢛꢆ(ꢉ" ꢆ'ꢘ(ꢑꢊꢜ
ꢇꢞꢝ Cꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢍꢊꢆ$&D ꢞꢅꢘꢗꢅꢘ ꢏꢜꢀ.ꢎFꢍꢄGꢐꢒ
ꢏꢎ5ꢀ*Fꢔ5ꢐ
ꢏꢍ5ꢀ*Fꢔ5ꢐ
ꢏꢜꢀ.ꢎFꢍꢄGꢐ
ꢔ/
ꢔ>
ꢔ<
ꢔ6
ꢂ,6
ꢏꢜꢍ5ꢍꢄG.
ꢜ ꢋ99F*ꢐ
ꢂ
ꢂ
Output 5 (General Purpose Output Pin). ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ ꢗꢞꢛꢘ
ꢗ(ꢉ 'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢞꢗꢊꢉꢜ$ꢛꢆ(ꢉ"
ꢆ'ꢘ(ꢑꢊꢜꢇꢞꢝ" ꢀꢈꢆꢉꢉꢊꢇ * Cꢍꢊ'ꢊ(ꢑꢊ ꢍꢊꢆ$&D ꢞꢛ Cꢍꢊ'ꢊ(ꢑꢊꢛ # ꢂ
ꢅꢇꢇD (ꢉ$('ꢆꢘꢞꢛ ꢞꢅꢘꢗꢅꢘ ꢏꢜꢍ5ꢍꢄGF*.ꢜ ꢋ99F*ꢐꢒ
ꢂ,>
ꢏꢎ5ꢍꢄGF*ꢐ
Output 7. (General Purpose Output Pin). ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ ꢗꢞꢛꢘ
ꢗ(ꢉ 'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢞꢗꢊꢉꢜ$ꢛꢆ(ꢉ"
ꢆ'ꢘ(ꢑꢊꢜꢇꢞꢝ" Cꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢍꢊꢆ$&D (ꢉ$('ꢆꢘꢞꢛ ꢞꢅꢘꢗꢅꢘ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ
* ꢏꢜꢎ5ꢍꢄGF*ꢐꢒ
ꢔ=
ꢔꢖ
ꢓꢕ
ꢓꢔ
ꢔ/
ꢔ>
ꢔ=
ꢔꢖ
ꢔꢕ
ꢔꢔ
ꢔꢓ
ꢔ1
ꢄꢔ
ꢄ1
ꢄ6
ꢄ>
#.ꢂ
#.ꢂ
#.ꢂ
#.ꢂ
Bi-Directional Data Bus.
Bi-Directional Data Bus.
Bi-Directional Data Bus.
MSB of the Eight Bit Bi-Directional Data Bus. ꢌꢇꢇ ꢘꢛꢆꢉ%+ꢊꢛ%
ꢚꢊꢘꢝꢊꢊꢉ ꢘꢈꢊ ꢀ,ꢋ ꢆꢉ$ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢘꢆ3ꢊ ꢗꢇꢆ'ꢊ ꢞꢑꢊꢛ ꢘꢈ(% ꢚꢅ%
ꢏ'ꢞꢉ%(%ꢘ(ꢉ- ꢞ+ ꢗ(ꢉ% ꢄꢕ ꢜ ꢄ>ꢐꢒ ꢎꢈꢊ ꢚꢅ% (% ꢘꢛ(ꢜ%ꢘꢆꢘꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ
ꢜꢀꢃ (ꢉꢗꢅꢘ (% Cꢈ(-ꢈD" ꢊ!'ꢊꢗꢘ $ꢅꢛ(ꢉ- ꢆꢉ #ꢌꢀ: '&'ꢇꢊ ꢏ(ꢉ ꢘꢈꢊ ?ꢜ
ꢁꢞ$ꢊꢐꢒ
ꢓꢓ
ꢓ1
ꢓ<
ꢓꢕ
ꢓꢔ
ꢔ<
ꢔ6
07ꢄ
7ꢀ
,Bꢍ Signal Ground.
No Connect.
ꢜ#7ꢎꢍ
ꢂ
Interrupt Request Output (Active Low, Open Drain).
ꢜ#7ꢎꢍ (% ꢆ%%ꢊꢛꢘꢊ$ ꢅꢗꢞꢉ ꢘꢈꢊ ꢞ''ꢅꢛꢛꢊꢉ'ꢊ ꢞ+ ꢞꢉꢊ ꢞꢛ ꢙꢞꢛꢊ ꢞ+ ꢘꢈꢊ
'ꢈ(ꢗH% ꢙꢆ%3ꢆꢚꢇꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ(ꢉ- 'ꢞꢉ$(ꢘ(ꢞꢉ%ꢒ ꢎꢈ(% %(-ꢉꢆꢇ ꢝ(ꢇꢇ ꢛꢊꢜ
ꢙꢆ(ꢉ ꢆ%%ꢊꢛꢘꢊ$ ꢘꢈꢛꢞꢅ-ꢈꢞꢅꢘ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢊꢛꢑ('ꢊ ꢍꢞꢅꢘ(ꢉꢊ ꢆꢉ$
ꢝ(ꢇꢇ ꢚꢊ ꢉꢊ-ꢆꢘꢊ$ ꢞꢉ'ꢊ ꢘꢈꢊ 'ꢞꢉ$(ꢘ(ꢞꢉꢏ%ꢐ 'ꢆꢅ%(ꢉ- ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢍꢊEꢅꢊ%ꢘ ꢈꢆ% ꢚꢊꢊꢉ ꢊꢇ(ꢙ(ꢉꢆꢘꢊ$ꢒ
ꢓ6
ꢓ/
ꢓ>
ꢓ=
ꢓꢓ
ꢓ1
ꢓ<
ꢓ6
ꢔ/
ꢔ>
ꢔ=
ꢔꢖ
ꢄ/
ꢄ<
ꢄꢓ
ꢄꢕ
#.ꢂ
#.ꢂ
#.ꢂ
#.ꢂ
Bi-Directional Data Bus.
Bi-Directional Data Bus.
Bi-Directional Data Bus.
LSB of the Eight Bit Bi-Directional Data Bus. ꢌꢇꢇ ꢘꢛꢆꢉ%+ꢊꢛ%
ꢚꢊꢘꢝꢊꢊꢉ ꢘꢈꢊ ꢀ,ꢋ ꢆꢉ$ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢘꢆ3ꢊ ꢗꢇꢆ'ꢊ ꢞꢑꢊꢛ ꢘꢈ(% ꢚꢅ%ꢒ
ꢎꢈꢊ ꢚꢅ% (% ꢘꢛ(ꢜ%ꢘꢆꢘꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ ꢜꢀꢃ (ꢉꢗꢅꢘ (% Cꢈ(-ꢈD" ꢊ!'ꢊꢗꢘ
$ꢅꢛ(ꢉ- ꢆꢉ #ꢌꢀ: '&'ꢇꢊ ꢏ(ꢉ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊꢐꢒ
ꢓꢖ
ꢓ/
ꢂ,/
ꢏꢜꢎ5ꢍꢄGFꢌꢐ
ꢂ
Output 6 (General Purpose Output). ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ ꢗ(ꢉ 'ꢆꢉ
ꢆꢇ%ꢞ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢞꢗꢊꢉ $ꢛꢆ(ꢉ" ꢆ'ꢘ(ꢑꢊꢜ
ꢇꢞꢝ" Cꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢍꢊꢆ$&D (ꢉ$('ꢆꢘꢞꢛ ꢞꢅꢘꢗꢅꢘ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ ꢌ
ꢏꢜꢎ5ꢍꢄGFꢌꢐꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
6
XR88C681
44 PLCC/
LCC
40 DIP,
CDP
28 DIP,
CDIP
Symbol
Type Description
1ꢕ
ꢓ>
ꢂ,<
ꢏꢍ5ꢍꢄG.
ꢋ99Fꢌꢐ
ꢂ
Output 4 (General Purpose Output). ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ ꢗ(ꢉ
'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢞꢗꢊꢉꢜ$ꢛꢆ(ꢉ"
ꢆ'ꢘ(ꢑꢊꢜꢇꢞꢝ" Cꢍꢊ'ꢊ(ꢑꢊꢛ ꢍꢊꢆ$&D ꢞꢛ C # ꢂ ꢅꢇꢇD (ꢉ$('ꢆꢘꢞꢛ
ꢞꢅꢘꢗꢅꢘ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ ꢌꢒ ꢏꢜꢍ5ꢍꢄGFꢌ.ꢜ ꢋ99Fꢌꢐ
1ꢔ
ꢓ=
ꢂ,ꢓ
ꢂ
Output 2 (General Purpose Output). ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ ꢗ(ꢉ
'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢆꢉ& ꢞ+ ꢘꢈꢊ +ꢞꢇꢜ
ꢇꢞꢝ(ꢉ-4 ꢎꢈꢊ ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢔ/5 ꢞꢛ ꢔ5 'ꢇꢞ'3
ꢞꢅꢘꢗꢅꢘ ꢏꢎ5ꢀꢌFꢔ/5 ꢞꢛ ꢎ5ꢀꢌFꢔ5ꢐ" ꢞꢛ ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇ ꢌ
ꢍꢊ'ꢊ(ꢑꢊꢛ ꢔ5 'ꢇꢞ'3 ꢞꢅꢘꢗꢅꢘ ꢏꢍ5ꢀꢌFꢔ5ꢐꢒ
ꢏꢎ5ꢀꢌFꢔ/ꢐ
ꢏꢎ5ꢀꢌꢜꢔ5ꢐ
ꢏꢍ5ꢀꢌFꢔ5ꢐ
1ꢓ
11
ꢓꢖ
1ꢕ
ꢓꢕ
ꢓꢔ
ꢂ,ꢕ
ꢏꢜꢍꢎꢃꢌꢐ
ꢂ
ꢂ
Output 0 (General Purpose Output). ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ ꢗ(ꢉ
'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢆ'ꢘ(ꢑꢊꢜꢇꢞꢝ"
ꢍꢊEꢅꢊ%ꢘꢜꢘꢞꢜꢃꢊꢉ$ ꢞꢅꢘꢗꢅꢘ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢏꢜꢍꢎꢃꢌꢐꢒ
ꢎ5ꢄꢌ
Transmitter Serial Data Output (Channel A). ꢎꢈꢊ
ꢇꢊꢆ%ꢘ %(-ꢉ(+('ꢆꢉꢘ ꢚ(ꢘ ꢞ+ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ +(ꢛ%ꢘꢒ
ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ (% ꢈꢊꢇ$ (ꢉ ꢘꢈꢊ ꢙꢆꢛ3(ꢉ- ꢏꢈ(-ꢈꢐ %ꢘꢆꢘꢊ ꢝꢈꢊꢉ ꢘꢈꢊ
ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% ($ꢇꢊ" $(%ꢆꢚꢇꢊ$" ꢞꢛ ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ 9ꢞ'ꢆꢇ
9ꢂꢂ,*ꢌꢀ: ꢙꢞ$ꢊꢒ #+ ꢆꢉ ꢊ!ꢘꢊꢛꢉꢆꢇ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ 'ꢇꢞ'3 (%
%ꢗꢊ'(+(ꢊ$" ꢎ5ꢀꢌ" ꢘꢈꢊ $ꢆꢘꢆ (% %ꢈ(+ꢘꢊ$ ꢞꢅꢘ ꢞ+ ꢘꢈꢊ ꢎꢃꢍ
ꢏꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛꢐ ꢞꢉ ꢘꢈꢊ +ꢆꢇꢇ(ꢉ- ꢘꢈꢊ ꢊ$-ꢊ ꢞ+
ꢘꢈꢊ 'ꢇꢞ'3ꢒ
1<
16
7ꢀ
No Connect.
1ꢔ
1ꢓ
ꢓꢓ
ꢓ1
ꢍ5ꢄꢌ
#
#
Receive Serial Data Input (Channel A). ꢎꢈꢊ ꢇꢊꢆ%ꢘ
%(-ꢉ(+('ꢆꢉꢘ ꢚ(ꢘ ꢞ+ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢛꢊ'ꢊ(ꢑꢊ$ +(ꢛ%ꢘꢒ #+ ꢆꢉ
ꢊ!ꢘꢊꢛꢉꢆꢇ ꢛꢊ'ꢊ(ꢑꢊꢛ 'ꢇꢞ'3" ꢍ5ꢀꢌ" (% %ꢗꢊ'(+(ꢊ$" ꢘꢈꢊ $ꢆꢘꢆ (%
%ꢆꢙꢗꢇꢊ$ ꢞꢉ ꢘꢈꢊ ꢛ(%(ꢉ- ꢊ$-ꢊ ꢞ+ ꢘꢈꢊ 'ꢇꢞ'3ꢒ
1/
5ꢔ.ꢀ9:
Crystal Output of External Clock Input. ꢎꢈ(% ꢗ(ꢉ (%
ꢘꢈꢊ 'ꢞꢉꢉꢊ'ꢘ(ꢞꢉ +ꢞꢛ ꢞꢉꢊ %($ꢊ ꢞ+ ꢘꢈꢊ 'ꢛ&%ꢘꢆꢇ ꢆꢉ$ ꢆ 'ꢆꢗꢆ'(ꢜ
ꢘꢞꢛ ꢘꢞ -ꢛꢞꢅꢉ$ ꢝꢈꢊꢉ ꢘꢈꢊ (ꢉꢘꢊꢛꢉꢆꢇ ꢞ%'(ꢇꢇꢆꢘꢞꢛ (% ꢅ%ꢊ$ꢒ #+ ꢘꢈꢊ
ꢞ%'(ꢇꢇꢆꢘꢞꢛ (% ꢉꢞꢘ ꢅ%ꢊ$" ꢆꢉ ꢊ!ꢘꢊꢛꢉꢆꢇ 'ꢇꢞ'3 %(-ꢉꢆꢇ ꢙꢅ%ꢘ ꢚꢊ
%ꢅꢗꢗꢇ(ꢊ$ ꢆꢘ ꢘꢈ(% (ꢉꢗꢅꢘꢒ
#ꢉ ꢞꢛ$ꢊꢛ +ꢞꢛ ꢘꢈꢊ 5ꢍ==ꢀ/=ꢔ $ꢊꢑ('ꢊ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢗꢛꢞꢗꢊꢛꢇ&"
ꢘꢈꢊ ꢅ%ꢊꢛ ꢙꢅ%ꢘ %ꢅꢗꢗꢇ& ꢆ %(-ꢉꢆꢇ ꢝ(ꢘꢈ +ꢛꢊEꢅꢊꢉ'(ꢊ% ꢚꢊꢜ
ꢘꢝꢊꢊꢉ ꢓꢒꢕꢁ8I ꢆꢉ$ <ꢒꢕꢁ8Iꢒ ꢎꢈ(% ꢛꢊEꢅ(ꢛꢊꢙꢊꢉꢘ 'ꢆꢉ ꢚꢊ
ꢙꢊꢘ ꢚ& ꢊ(ꢘꢈꢊꢛ ꢆ 'ꢛ&%ꢘꢆꢇ ꢞ%'(ꢇꢇꢆꢘꢞꢛ ꢞꢛ ꢚ& ꢘꢈꢊ ꢊ!ꢘꢊꢛꢉꢆꢇ
ꢎꢎ9ꢜ'ꢞꢙꢗꢆꢘ(ꢚꢇꢊ 'ꢇꢞ'3 %(-ꢉꢆꢇꢒ
1>
11
ꢓ<
5ꢓ
ꢂ
Crystal Input. ꢀꢞꢉꢉꢊ'ꢘ(ꢞꢉ +ꢞꢛ ꢘꢈꢊ ꢞꢉꢊ %($ꢊ ꢞ+ ꢘꢈꢊ 'ꢛ&%ꢜ
ꢘꢆꢇ ꢏꢞꢗꢗꢞ%(ꢘꢊ ꢞ+ 5ꢔ.ꢀ9:ꢐꢒ #+ ꢘꢈꢊ ꢞ%'(ꢇꢇꢆꢘꢞꢛ (% ꢅ%ꢊ$" ꢆ
'ꢆꢗꢆ'(ꢘꢞꢛ ꢙꢅ%ꢘ ꢆꢇ%ꢞ ꢚꢊ 'ꢞꢉꢉꢊ'ꢘꢊ$ +ꢛꢞꢙ ꢘꢈ(% ꢗ(ꢉ ꢘꢞ
-ꢛꢞꢅꢉ$ꢒ ꢎꢈ(% ꢗ(ꢉ ꢙꢅ%ꢘ ꢚꢊ ꢇꢊ+ꢘ ꢞꢗꢊꢉ (+ ꢆꢉ ꢊ!ꢘꢊꢛꢉꢆꢇ 'ꢇꢞ'3
(% %ꢅꢗꢗꢇ(ꢊ$ ꢆꢘ 5ꢔ.ꢀ9:ꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
/
XR88C681
44 PLCC/
LCC
40 DIP,
CDP
28 DIP,
CDIP
Symbol
Type
Description
1=
1<
ꢓ6
ꢍ2ꢃ2ꢎ
#
Master Reset (Active High). ꢌ%%ꢊꢛꢘ(ꢉ- ꢘꢈ(% (ꢉꢗꢅꢘ 'ꢇꢊꢆꢛ% (ꢉꢜ
ꢘꢊꢛꢉꢆꢇ ꢛꢊ-(%ꢘꢊꢛ%" ꢃꢍ" #ꢃꢍ" #ꢁꢍ" ꢂ,ꢍ" ꢂ,ꢀꢍ" ꢆꢉ$ (ꢉ(ꢘ(ꢆꢇ(Iꢊ%
ꢘꢈꢊ #;ꢍ ꢘꢞ ꢕ ꢔ/ꢒ ꢌ%%ꢊꢛꢘ(ꢉ- ꢘꢈ(% (ꢉꢗꢅꢘ ꢆꢇ%ꢞ %ꢘꢞꢗ% ꢘꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ.
ꢎ(ꢙꢊꢛ" ꢗꢅꢘ% ꢂ,ꢕ ꢜ ꢂ,> (ꢉ ꢘꢈꢊ ꢈ(-ꢈ %ꢘꢆꢘꢊ" ꢆꢉ$ ꢗꢇꢆ'ꢊ% ꢚꢞꢘꢈ
%ꢊꢛ(ꢆꢇ 'ꢈꢆꢉꢉꢊꢇ% (ꢉ ꢘꢈꢊ (ꢉꢆ'ꢘ(ꢑꢊ %ꢘꢆꢘꢊ ꢝ(ꢘꢈ ꢎ5ꢄꢌ ꢆꢉ$ ꢎ5ꢄ*
ꢞꢅꢘꢗꢅꢘ% ꢙꢆꢛ3(ꢉ- ꢏꢈ(-ꢈꢐꢒ
1ꢖ
<ꢕ
<ꢔ
<ꢔ
16
1/
1>
1>
ꢓ/
ꢓ>
ꢜꢀꢃ
#
#
#
#
Chip Select (Active Low). ꢎꢈꢊ $ꢆꢘꢆ ꢚꢅ% (% ꢘꢛ(ꢜ%ꢘꢆꢘꢊ$ ꢝꢈꢊꢉ
ꢜꢀꢃ (% Cꢈ(-ꢈꢒD ꢄꢆꢘꢆ ꢘꢛꢆꢉ%+ꢊꢛ% ꢚꢊꢘꢝꢊꢊꢉ ꢘꢈꢊ ꢀ,ꢋ ꢆꢉ$ ꢘꢈꢊ
ꢄꢋꢌꢍꢎ ꢑ(ꢆ ꢄꢕ ꢜ ꢄ> ꢆꢛꢊ ꢊꢉꢆꢚꢇꢊ$ ꢝꢈꢊꢉ ꢜꢀꢃ (% CꢇꢞꢝDꢒ
#,ꢓ
ꢏꢀ.ꢎF25ꢐ
Input 2. (General Purpose Input). ꢎꢈ(% (ꢉꢗꢅꢘ ꢗ(ꢉ 'ꢆꢉ ꢆꢇ%ꢞ
ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ Cꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢊ!ꢘꢊꢛꢉꢆꢇ
'ꢇꢞ'3D (ꢉꢗꢅꢘ ꢏꢀ.ꢎF25ꢐꢒ
#,/
ꢏꢍ5ꢀ*ꢐ
Input 6 (I-Mode). 0ꢊꢉꢊꢛꢆꢇ ,ꢅꢛꢗꢞ%ꢊ #ꢉꢗꢅꢘ ꢗ(ꢉꢒ ꢎꢈ(% (ꢉꢗꢅꢘ ꢗ(ꢉ
'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ 2!ꢘꢊꢛꢉꢆꢇ ꢍꢊ'ꢊ(ꢑꢜ
ꢊꢛ ꢀꢇꢞ'3 +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ * ꢏꢍ5ꢀ*ꢐꢒ
ꢜ#ꢌꢀ:
Interrupt Acknowledge Input (Z-Mode). ꢌ'ꢘ(ꢑꢊ 9ꢞꢝꢒ
ꢎꢈ(% (ꢉꢗꢅꢘ (% ꢘꢈꢊ ꢀ,ꢋH% ꢛꢊ%ꢗꢞꢉ%ꢊ ꢘꢞ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢍꢊEꢅꢊ%ꢘ
(%%ꢅꢊ$ ꢚ& ꢘꢈꢊ ꢄꢋꢌꢍꢎ $ꢊꢑ('ꢊꢒ Bꢈꢊꢉ ꢘꢈꢊ ꢀ,ꢋ ꢆ%%ꢊꢛꢘ% ꢘꢈ(%
(ꢉꢗꢅꢘ" (ꢘ (ꢉ$('ꢆꢘꢊ% ꢘꢈꢆꢘ ꢘꢈꢊ ꢄꢋꢌꢍꢎH% (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ (% ꢆꢚꢞꢅꢘ
ꢘꢞ ꢚꢊ %ꢊꢛꢑ('ꢊ$" ꢆꢉ$ ꢘꢈꢆꢘ ꢘꢈꢊ ꢑꢊꢛ& ꢉꢊ!ꢘ '&'ꢇꢊ ꢝ(ꢇꢇ ꢚꢊ ꢆꢉ #ꢉꢘꢊꢛꢜ
ꢛꢅꢗꢘ ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊ ꢀ&'ꢇꢊꢒ ꢎꢈꢊ ꢄꢋꢌꢍꢎ ꢝ(ꢇꢇ ꢛꢊ%ꢗꢞꢉ$ ꢘꢞ ꢘꢈꢊ
ꢀ,ꢋH% #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊ ꢚ& ꢗꢇꢆ'(ꢉ- ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ ꢍꢊ-(%ꢘꢊꢛ ꢏ#;ꢍꢐ ꢞꢉ ꢘꢈꢊ $ꢆꢘꢆ ꢚꢅ% ꢏꢄꢕ ꢜ ꢄ>ꢐꢒ
<ꢓ
<ꢓ
1=
1=
#,6
ꢏꢎ5ꢀ*ꢐ
#
Input 5 (I-Mode). 0ꢊꢉꢊꢛꢆꢇ ,ꢅꢛꢗꢞ%ꢊ #ꢉꢗꢅꢘ ꢗ(ꢉꢒ ꢎꢈ(% ꢗ(ꢉ 'ꢆꢉ
ꢆꢇ%ꢞ ꢚꢊ 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢊ!ꢘꢊꢛꢉꢆꢇ 'ꢇꢞ'3 (ꢉꢗꢅꢘ +ꢞꢛ
ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢞ+ ꢀꢈꢆꢉꢉꢊꢇ * ꢏꢎ5ꢀ*ꢐꢒ
#2ꢂ
ꢏ?ꢜꢁꢞ$ꢊꢐ
ꢂ
Interrupt Enable Output (Z-Mode). ꢌ'ꢘ(ꢑꢊ 8(-ꢈꢒ
ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ ꢗ(ꢉ (% ꢉꢞꢛꢙꢆꢇꢇ& Cꢈ(-ꢈDꢒ 8ꢞꢝꢊꢑꢊꢛ" ꢊ(ꢘꢈꢊꢛ ꢞ+ ꢘꢈꢊ
+ꢞꢇꢇꢞꢝ(ꢉ- ꢘꢝꢞ 'ꢞꢉ$(ꢘ(ꢞꢉ% 'ꢆꢉ 'ꢆꢅ%ꢊ ꢘꢈ(% ꢞꢅꢘꢗꢅꢘ ꢗ(ꢉ ꢘꢞ ꢚꢊ ꢉꢊꢜ
-ꢆꢘꢊ$ ꢏꢘꢞ--ꢇꢊ$ CꢇꢞꢝDꢐꢒ
ꢔꢒ #+ ꢘꢈꢊ #2# ꢏ#ꢉꢘꢊꢛꢛꢅꢗꢘ 2ꢉꢆꢚꢇꢊ #ꢉꢗꢅꢘꢐ ꢗ(ꢉ (% CꢇꢞꢝDꢒ #+ #2ꢂ (%
CꢇꢞꢝD ꢚꢊ'ꢆꢅ%ꢊ ꢞ+ ꢘꢈꢊ #2# ꢗ(ꢉ" #2ꢂ ꢝ(ꢇꢇ ꢘꢞ--ꢇꢊ Cꢈ(-ꢈD ꢞꢉ'ꢊ
ꢘꢈꢊ #2# ꢈꢆ% ꢘꢞ--ꢇꢊ$ Cꢈ(-ꢈDꢒ
ꢓꢒ ꢎꢈꢊ ꢄꢋꢌꢍꢎ ꢈꢆ% (%%ꢅꢊ$ ꢆꢉ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢍꢊEꢅꢊ%ꢘ ꢘꢞ ꢘꢈꢊ ꢀ,ꢋ
ꢏꢜ#7ꢎꢍ ꢗ(ꢉ (% ꢘꢞ--ꢇꢊ$ CꢇꢞꢝDꢐꢒ #+ #2ꢂ (% CꢇꢞꢝD ꢚꢊ'ꢆꢅ%ꢊ ꢘꢈꢊ
ꢄꢋꢌꢍꢎ ꢈꢆ% ꢛꢊEꢅꢊ%ꢘꢊ$ ꢆꢉ #ꢉꢘꢊꢛꢛꢅꢗꢘ" ꢘꢈꢊꢉ #2ꢂ ꢝ(ꢇꢇ ꢛꢊꢙꢆ(ꢉ
CꢇꢞꢝD" ꢘꢈꢛꢞꢅ-ꢈꢞꢅꢘ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢊꢛꢑ('ꢊ ꢍꢞꢅꢘ(ꢉꢊ" ꢅꢉꢘ(ꢇ ꢘꢈꢊ
ꢀ,ꢋ ꢈꢆ% (ꢉꢑꢞ3ꢊ$ ꢘꢈꢊ CD 'ꢞꢙꢙꢆꢉ$ꢒ
<1
<1
1ꢖ
1ꢖ
#,<
ꢏꢍ5ꢀꢌꢐ
#
#
Input 4 (I-Mode). 0ꢊꢉꢊꢛꢆꢇ ,ꢅꢛꢗꢞ%ꢊ #ꢉꢗꢅꢘ ꢗ(ꢉꢒ ꢎꢈ(% (ꢉꢗꢅꢘ ꢗ(ꢉ
'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢊ!ꢘꢊꢛꢉꢆꢇ 'ꢇꢞ'3 (ꢉꢗꢅꢘ
+ꢞꢛ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢞ+ ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢏꢍ5ꢀꢌꢐꢒ
#2#
ꢏ?ꢜꢁꢞ$ꢊꢐ
Interrupt Enable Input (Z-Mode). ꢌ'ꢘ(ꢑꢊ 8(-ꢈꢒ
#+ ꢘꢈ(% ꢆ'ꢘ(ꢑꢊꢜꢈ(-ꢈ (ꢉꢗꢅꢘ (% ꢆꢘ ꢆ ꢇꢞ-(' Cꢈ(-ꢈD" ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% 'ꢆꢜ
ꢗꢆꢚꢇꢊ ꢞ+ -ꢊꢉꢊꢛꢆꢘ(ꢉ- ꢆꢇꢇ ꢉꢞꢉꢜꢙꢆ%3ꢊ$ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢍꢊEꢅꢊ%ꢘ% ꢘꢞ ꢘꢈꢊ
ꢀ,ꢋꢒ #+ ꢘꢈ(% (ꢉꢗꢅꢘ (% ꢆꢘ ꢆ ꢇꢞ-(' CꢇꢞꢝD" ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% (ꢉꢈ(ꢚ(ꢘꢊ$
+ꢛꢞꢙ -ꢊꢉꢊꢛꢆꢘ(ꢉ- ꢆꢉ& #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢍꢊEꢅꢊ%ꢘ% ꢘꢞ ꢘꢈꢊ ꢀ,ꢋꢒ
<<
<ꢕ
ꢓ=
;
ꢀꢀ
,Bꢍ Most Positive Power Supply.
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
>
XR88C681
1, 2, 3
DC ELECTRICAL CHARACTERISTICS
Test Conditions: ꢎ J ꢕ ꢜ >ꢕꢀꢀ" ; J 6; ꢀ 6K ꢅꢉꢇꢊ%% ꢞꢘꢈꢊꢛꢝ(%ꢊ %ꢗꢊ'(+(ꢊ$ꢒ
ꢌ
ꢀꢀ
Symbol
Parameter
Min.
ꢕꢒ6
ꢓꢒꢕ
ꢓꢒꢓ
<ꢒꢕ
Typ.
Max.
Unit
;
Conditions
;
#ꢉꢗꢅꢘ 9ꢞꢝ ;ꢞꢇꢘꢆ-ꢊ
#ꢉꢗꢅꢘ 8(-ꢈ ;ꢞꢇꢘꢆ-ꢊ
ꢕꢒ=
#9
#8
#8
;
;
;
ꢀꢀ
;
#ꢉꢗꢅꢘ 8(-ꢈ ;ꢞꢇꢘꢆ-ꢊ ꢏꢁ(ꢇ(ꢘꢆꢛ&ꢐ
#ꢉꢗꢅꢘ 8(-ꢈ ;ꢞꢇꢘꢆ-ꢊ ꢏ5ꢔ.ꢀ9:ꢐ
ꢂꢅꢘꢗꢅꢘ 9ꢞꢝ ;ꢞꢇꢘꢆ-ꢊ
;
ꢎꢌ J ꢜ66ꢀꢀ ꢘꢞ ꢔꢓ6ꢀꢀ
;
#85ꢔ
;
ꢀꢀ
;
;
ꢂ9
ꢕꢒ<
;
#ꢂ9 J ꢓꢒ<ꢙꢌ
;
ꢂꢅꢘꢗꢅꢘ 8(-ꢈ ;ꢞꢇꢘꢆ-ꢊ
ꢓꢒ<
ꢜꢓ6
ꢜ1ꢕ
;
#
ꢂ8 J ꢜ<ꢕꢕ• ꢌ
ꢂ8
#
#ꢉꢗꢅꢘ 9ꢊꢆ3ꢆ-ꢊ ꢀꢅꢛꢛꢊꢉꢘ
ꢃꢊꢇꢊ'ꢘ ,(ꢉ 9ꢊꢆ3ꢆ-ꢊ ꢀꢅꢛꢛꢊꢉꢘ
5ꢔ #ꢉꢗꢅꢘ 9ꢞꢝ ꢀꢅꢛꢛꢊꢉꢘ
5ꢓ #ꢉꢗꢅꢘ 9ꢞꢝ ꢀꢅꢛꢛꢊꢉꢘ
5ꢔ #ꢉꢗꢅꢘ 8(-ꢈ ꢀꢅꢛꢛꢊꢉꢘ
5ꢓ #ꢉꢗꢅꢘ 8(-ꢈ ꢀꢅꢛꢛꢊꢉꢘ
ꢓ6
• ꢌ
• ꢌ
• ꢌ
ꢙꢌ
• ꢌ
• ꢌ
• ꢌ
;
;
;
#7 J ꢕ ꢘꢞ ;ꢀꢀ
#7 J ꢕ ꢘꢞ ;ꢀꢀ
#7 J ꢕ
#9
#
A1ꢕ
#9ꢃ29
#
ꢜꢓꢕ
ꢜ>
5ꢔ9
#
5ꢓ9
#
ꢓꢕ
ꢓꢕ
;
;
;
#7 J ;ꢀꢀ
5#8
#
#7 J ;ꢀꢀ
5ꢓ8
#
99
ꢄꢆꢘꢆ *ꢅ% ꢎꢛ(ꢜꢃꢘꢆꢘꢊ 9ꢊꢆ3ꢆ-ꢊ
ꢀꢅꢛꢛꢊꢉꢘ
ꢜꢔꢕ
ꢜꢔꢕ
ꢔꢕ
ꢔꢕ
ꢂ J ꢕ ꢘꢞ ;ꢀꢀ
#
ꢂꢗꢊꢉ ꢄꢛꢆ(ꢉ ꢂꢅꢘꢗꢅꢘ 9ꢊꢆ3ꢆ-ꢊ
ꢀꢅꢛꢛꢊꢉꢘ
• ꢌ
;
ꢂ J ꢕ ꢘꢞ ;ꢀꢀ
ꢂꢀ
#
,ꢞꢝꢊꢛ ꢃꢅꢗꢗꢇ& ꢀꢅꢛꢛꢊꢉꢘ<
,ꢞꢝꢊꢛ ꢃꢅꢗꢗꢇ& ꢀꢅꢛꢛꢊꢉꢘ<
/
1
ꢔ6
ꢔꢕ
ꢙꢌ
ꢙꢌ
ꢌ'ꢘ(ꢑꢊ ꢁꢞ$ꢊ
ꢀꢀꢌ
#
ꢃꢘꢆꢉ$ꢚ& ꢁꢞ$ꢊ
ꢀꢀꢃ
Notes
1.Parameters are valid over the specified temperature and operating supply ranges. Typical values are 25ꢀC, VCC = 5V and typical
processing parameters.
2.All voltages are referenced to ground (GND). For testing, input signal levels are 0.4V and 2.4V with a transition time of 20ns
maximum. All time measurements are referenced at input voltages of 0.8V and 2.0V as appropriate. See Figure 50.
3.For prime grade N, P, J, L, M, ML, VCC = 5V + 10%.
4.Measured operating with a 3.6864MHz crystal and with all outputs open.
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
=
XR88C681
1, 2, 3
AC ELECTRICAL CHARACTERISTICS
Test Conditions: ꢎ J ꢕ ꢜ >ꢕꢀꢀ" ; J 6; ꢀ 6K ꢅꢉꢇꢊ%% ꢞꢘꢈꢊꢛꢝ(%ꢊ %ꢗꢊ'(+(ꢊ$ꢒ
ꢌ
ꢀꢀ
Symbol
Reset Timing (See Figure 51)
ꢘꢍ2ꢃ ꢍ2ꢃ2ꢎ ,ꢅꢇ%ꢊ B($ꢘꢈ
Parameter
Min.
Typ.
Max.
Unit
Conditions
ꢔꢒꢕ
• ꢌ
XR88C681 Read and Write Cycle Timing (Figure 52)4
ꢘꢌꢃ
ꢌꢕꢜꢌ1 ꢃꢊꢘꢅꢗ ꢎ(ꢙꢊ ꢘꢞ ꢍꢄ" Bꢍ
9ꢞꢝ
ꢔꢕ
ꢉ%
ꢉ%
ꢘꢌ8
ꢌꢕꢜꢌ1 8ꢞꢇ$ ꢎ(ꢙꢊ +ꢛꢞꢙ ꢍꢄ" Bꢍ
9ꢞꢝ
ꢕ
ꢘꢀꢃ
ꢘꢀ8
ꢀꢃ ꢃꢊꢘꢅꢗ ꢎ(ꢙꢊ ꢘꢞ ꢍꢄ" Bꢍ 9ꢞꢝ
ꢕ
ꢕ
ꢉ%
ꢉ%
ꢀꢃ 8ꢞꢇ$ ꢎ(ꢙꢊ +ꢛꢞꢙ ꢜꢍꢄ" ꢜBꢍ
8(-ꢈ
ꢘꢍB
ꢘꢄꢄ
ꢜꢍꢄ" ꢜBꢍ ,ꢅꢇ%ꢊ B($ꢘꢈ
ꢓꢓ6
ꢉ%
ꢉ%
ꢉ%
ꢉ%
ꢉ%
ꢉ%
ꢄꢆꢘꢆ ;ꢆꢇ($ +ꢛꢞꢙ ꢜꢍꢄ 9ꢞꢝ
/ꢕ
ꢔ>6
ꢔꢕꢕ
ꢘꢄ
ꢄꢆꢘꢆ *ꢅ% ꢇꢞꢆꢘ(ꢉ- +ꢛꢞꢙ ꢜꢍꢄ 8(-ꢈ
ꢄꢆꢘꢆ ꢃꢊꢘꢅꢗ ꢎ(ꢙꢊ ꢘꢞ ꢜBꢍ 8(-ꢈ
ꢄꢆꢘꢆ 8ꢞꢇ$ ꢎ(ꢙꢊ +ꢛꢞꢙ ꢜBꢍ 8(-ꢈ
ꢔꢕ
ꢔꢕꢕ
6
ꢘꢄꢃ
ꢘꢄ8
ꢘꢍBꢄ
8(-ꢈ ꢎ(ꢙꢊ *ꢊꢘꢝꢊꢊꢉ ꢍꢊꢆ$%
ꢆꢉ$.ꢞꢛ Bꢛ(ꢘꢊ%6" /
ꢔꢕꢕ
Z-Mode Interrupt Cycle Timing (Figure 53)
ꢘꢄ#ꢂ
ꢘ#ꢌꢃ
ꢘ#ꢌ8
ꢘ2#ꢃ
ꢘ2ꢂꢄ
#2ꢂ ꢄꢊꢇꢆ& ꢎ(ꢙꢊ +ꢛꢞꢙ #2#
ꢔꢕꢕ
ꢔꢕꢕ
ꢉ%
ꢉ%
ꢉ%
ꢉ%
ꢉ%
ꢜ#ꢌꢀ: ꢃꢊꢘꢅꢗ ꢎ(ꢙꢊ ꢘꢞ ꢜꢍꢄ 9ꢞꢝ>
ꢜ#ꢌꢀ: 8ꢞꢇ$ ꢎ(ꢙꢊ +ꢛꢞꢙ ꢜꢍꢄ 8(-ꢈ
#2# ꢃꢊꢘꢅꢗ ꢎ(ꢙꢊ ꢘꢞ ꢍꢄ 9ꢞꢝ
ꢕ
6ꢕ
#2ꢂ ꢄꢊꢇꢆ& ꢎ(ꢙꢊ +ꢛꢞꢙ ꢜ#7ꢎꢍ 9ꢞꢝ
Port Timing (Figure 54)4
ꢘ,ꢃ
ꢘ,8
ꢘ,ꢄ
,ꢞꢛꢘ #ꢉꢗꢅꢘ ꢃꢊꢘꢅꢗ ꢎ(ꢙꢊ ꢘꢞ
ꢜꢍꢄ.ꢜꢀꢃ 9ꢞꢝ
ꢕ
ꢕ
ꢉ%
ꢉ%
ꢉ%
,ꢞꢛꢘ #ꢉꢗꢅꢘ 8ꢞꢇ$ ꢎ(ꢙꢊ +ꢛꢞꢙ
ꢜꢍꢄ.ꢜꢀꢃ 8(-ꢈ
,ꢞꢛꢘ ꢂꢅꢘꢗꢅꢘ ;ꢆꢇ($ +ꢛꢞꢙ ꢜBꢍ.ꢜꢀꢃ
8(-ꢈ
<ꢕꢕ
Interrupt Output Timing (Figure 55)
ꢘ#ꢍ ꢜ#7ꢎꢍ ꢞꢛ ꢂ,1 ꢜ ꢂ,> ꢝꢈꢊꢉ ꢅ%ꢊ$
1ꢕꢕ
1ꢕꢕ
ꢉ%
ꢉ%
ꢆ% #ꢉꢘꢊꢛꢛꢅꢗꢘ% 8(-ꢈ +ꢛꢞꢙ4 ꢀꢇꢊꢆꢛ ꢞ+
#ꢉꢘꢊꢛꢛꢅꢗꢘ% ꢃꢘꢆꢘꢅ% *(ꢘ% (ꢉ #ꢃꢍ ꢞꢛ
#,ꢀꢍ ꢀꢇꢊꢆꢛ ꢞ+ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢆ%3 (ꢉ
#ꢁꢍ
Clock Timing (Figure 56)
ꢘꢀ9: 5ꢔ.ꢀ9: ꢏ2!ꢘꢊꢛꢉꢆꢇꢐ 8(-ꢈ ꢞꢛ 9ꢞꢝ
ꢎ(ꢙꢊ
ꢔꢕꢕ
ꢉ%
ꢘꢀ9:
5ꢔ.ꢀ9: ꢀꢛ&%ꢘꢆꢇ ꢞꢛ 2!ꢘꢊꢛꢉꢆꢇ
ꢛꢊEꢅꢊꢉ'&
>ꢒ1>ꢓ
ꢁ8I
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢖ
XR88C681
1, 2, 3
AC ELECTRICAL CHARACTERISTICS
(CONT’D)
Test Conditions: ꢎ J ꢕ ꢜ >ꢕꢀꢀ" ; J 6; ꢀ 6K ꢅꢉꢇꢊ%% ꢞꢘꢈꢊꢛꢝ(%ꢊ %ꢗꢊ'(+(ꢊ$ꢒ
ꢌ
ꢀꢀ
Symbol
Parameter
Min.
Typ.
Max.
Unit
Conditions
Clock Timing (Figure 56) (Cont’d.)
ꢘꢀꢎꢀ
ꢘꢀꢎꢀ
ꢘꢍꢎ5
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ 2!ꢘꢊꢛꢉꢆꢇ ꢀꢇꢞ'3
8(-ꢈ ꢞꢛ 9ꢞꢝ ꢎ(ꢙꢊ ꢏ#,ꢓꢐ
ꢔꢕꢕ
ꢕ
ꢉ%
ꢁ8I
ꢉ%
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ 2!ꢘꢊꢛꢉꢆꢇ ꢀꢇꢞ'3
ꢛꢊEꢅꢊꢉ'&
>ꢒ1>ꢓ
ꢍ5ꢀꢉ ꢆꢉ$ ꢎ5ꢀꢉ ꢏ2!ꢘꢊꢛꢉꢆꢇꢐ 8(-ꢈ
ꢞꢛ 9ꢞꢝ ꢎ(ꢙꢊ=
ꢓꢓꢕ
+
ꢍ5ꢀꢉ ꢆꢉ$ ꢎ5ꢀꢉ ꢏ2!ꢘꢊꢛꢉꢆꢇꢐ
ꢍꢎ5
ꢛꢊEꢅꢊꢉ'&
ꢔ/5
ꢔ5
ꢕ
ꢕ
ꢔ/ꢒꢕ
ꢔꢒꢕ
ꢁ8I
ꢁ8I
Transmitter Timing (Figure 57)
ꢘꢎ5ꢄ
ꢘꢎꢀꢃ
ꢘꢍ5ꢃ
ꢘꢍ58
ꢎ5ꢄ ꢂꢅꢘꢗꢅꢘ ꢄꢊꢇꢆ& ꢜ ꢎ5ꢀ
ꢏ2!ꢘꢊꢛꢉꢆꢇꢐ 9ꢞꢝ
16ꢕ
ꢔ6ꢕ
ꢉ%
ꢉ%
ꢉ%
ꢉ%
ꢎ5ꢄ ꢂꢅꢘꢗꢅꢘ ꢄꢊꢇꢆ& ꢜ ꢎ5ꢀ
ꢏ#ꢉꢘꢊꢛꢉꢆꢇꢐ ꢂꢅꢘꢗꢅꢘ 9ꢞꢝ
ꢍ5ꢄ ꢄꢆꢘꢆ ꢃꢊꢘꢅꢗ ꢎ(ꢙꢊ ꢘꢞ ꢍ5ꢀ
ꢏ2!ꢘꢊꢛꢉꢆꢇꢐ 8(-ꢈ
ꢓ<ꢕ
ꢓꢕꢕ
ꢍ5ꢄ ꢄꢆꢘꢆ 8ꢞꢇ$ ꢎ(ꢙꢊ +ꢛꢞꢙ ꢍ5ꢀ
ꢏ2!ꢘꢊꢛꢉꢆꢇꢐ 8(-ꢈ
Notes
1.Parameters are valid over the specified temperature and operating supply ranges. Typical values are 25ꢀC, VCC = 5V and typical
processing parameters.
2.All voltages are referenced to ground (GND). For testing, input signal levels are 0.4V and 2.4V with a transition time of 20ns
maximum. All time measurements are referenced at input voltages of 0.8V and 2.0V as appropriate. See Figure 50.
3.AC test conditions for outputs: CL = 50pF, RL = 2.7k• to VCC
.
4.If ꢜCS is used as the strobing input, this parameter defines the minimum high time between ꢜCSs.
5.Consecutive write operations to the same register require at least three edges of the X1 clock between writes.
6.This specification imposes a 6 MHz maximum 68000 clock frequency if a read or write cycle follows immediately after the previous
read or write cycle. A higher 68000 clock can be used if this is not the case.
7.This specification imposes a lower bound on ꢜCS and ꢜIACK low, guaranteeing that they will be low for at least one CLK period.
8.Theminimumhigh timemustbe atleast 1.5timestheX1/CLKperiodand theminimum lowtime mustbe atleast equal to theX1/CLK
period if either channel’s Receiver is operating in external 1X clock mode.
Specifications are subject to change without notice
1
ABSOLUTE MAXIMUM RATINGS
ꢄꢀ ꢃꢅꢗꢗꢇ& ;ꢞꢇꢘꢆ-ꢊ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ >;
ꢃꢘꢞꢛꢆ-ꢊ ꢎꢊꢙꢗꢊꢛꢆꢘꢅꢛꢊ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢜ/6ꢀ ꢀ ꢘꢞ ꢔ6ꢕꢀ ꢀ
ꢌꢇꢇ ;ꢞꢇꢘꢆ-ꢊ% ꢝ(ꢘꢈ
ꢓ
ꢛꢊ%ꢗꢊ'ꢘ ꢘꢞ 0ꢛꢞꢅꢉ$ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢒ ꢜꢕꢒ6; ꢘꢞ A>;
1.Stresses above those listed undertheAbsolute MaximumRatingsmaycause permanentdamagetothedevice. This isa stressrat-
ing only, and functional operation of the device at these or any other conditions above those indicated in the “Electrical Characteris-
tics” section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢔꢕ
XR88C681
2.Thisproductincludescircuitryspecificallydesignedfortheprotectionofitsinternaldevicesfromdamagingeffectsofexcessivestat-
ic charge. Nonetheless, it is suggested that conventional precautions be taken to avoid applying any voltage larger than the rated
maximum.
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢔꢔ
XR88C681
SYSTEM DESCRIPTION
ꢎꢈꢊ 5ꢍ==ꢀ/=ꢔ 'ꢞꢉ%(%ꢘ% ꢞ+ ꢘꢝꢞ (ꢉ$ꢊꢗꢊꢉ$ꢊꢉꢘ" +ꢅꢇꢇꢜ$ꢅꢗꢇꢊ!
'ꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉ 'ꢈꢆꢉꢉꢊꢇ%L ꢊꢆ'ꢈ 'ꢞꢉ%(%ꢘ(ꢉ- ꢞ+ ꢘꢈꢊ(ꢛ ꢞꢝꢉ
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ꢙꢆ& ꢚꢊ (ꢉ$ꢊꢗꢊꢉ$ꢊꢉꢘꢇ& ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ +ꢞꢛ ꢞꢗꢊꢛꢆꢘ(ꢉ- ꢙꢞ$ꢊ
ꢆꢉ$ $ꢆꢘꢆ +ꢞꢛꢙꢆꢘꢒ ꢎꢈꢊ ꢄꢋꢌꢍꢎ 'ꢆꢉ (ꢉꢘꢊꢛ+ꢆ'ꢊ ꢘꢞ ꢆ ꢝ($ꢊ
ꢁ ꢃꢊꢛ(ꢆꢇ ꢀꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉ ꢀꢈꢆꢉꢉꢊꢇ% ꢌ ꢆꢉ$ *
ꢁ ꢂꢗꢊꢛꢆꢘ(ꢞꢉ ꢀꢞꢉꢘꢛꢞꢇ
ꢁ ꢎ(ꢙ(ꢉ- ꢀꢞꢉꢘꢛꢞꢇ
ꢁ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ
A. DATA BUS BUFFER
ꢛꢆꢉ-ꢊ ꢞ+ ꢗꢛꢞ'ꢊ%%ꢞꢛ% ꢝ(ꢘꢈ
ꢆ ꢙ(ꢉ(ꢙꢆꢇ ꢆꢙꢞꢅꢉꢘ ꢞ+
'ꢞꢙꢗꢞꢉꢊꢉꢘ%ꢒ ꢎꢈꢊ ꢞꢗꢊꢛꢆꢘ(ꢉ- %ꢗꢊꢊ$ ꢞ+ ꢊꢆ'ꢈ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢆꢉ$
ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢙꢆ& ꢚꢊ %ꢊꢇꢊ'ꢘꢊ$ +ꢛꢞꢙ ꢞꢉꢊ ꢞ+ ꢓ1 (ꢉꢘꢊꢛꢉꢆꢇꢇ&
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(ꢉꢘꢊꢛꢉꢆꢇ 'ꢞꢅꢉꢘꢊꢛ.ꢘ(ꢙꢊꢛ" ꢞꢛ +ꢛꢞꢙ ꢆꢉ ꢊ!ꢘꢊꢛꢉꢆꢇꢇ& %ꢅꢗꢗꢇ(ꢊ$ ꢔ! ꢞꢛ
ꢔ/! 'ꢇꢞ'3ꢒ ꢎꢈꢊ ꢚ(ꢘ ꢛꢆꢘꢊ -ꢊꢉꢊꢛꢆꢘꢞꢛ ꢏꢘꢈꢊ %ꢞꢅꢛ'ꢊ ꢞ+ ꢘꢈꢊ ꢓ1
$(++ꢊꢛꢊꢉꢘ +(!ꢊ$ ꢚ(ꢘ ꢛꢆꢘꢊ%ꢐ 'ꢆꢉ ꢞꢗꢊꢛꢆꢘꢊ $(ꢛꢊ'ꢘꢇ& +ꢛꢞꢙ ꢆ 'ꢛ&%ꢘꢆꢇ
'ꢞꢉꢉꢊ'ꢘꢊ$ ꢆ'ꢛꢞ%% ꢘꢝꢞ ꢗ(ꢉ% ꢞꢛ +ꢛꢞꢙ ꢆꢉ ꢊ!ꢘꢊꢛꢉꢆꢇ 'ꢇꢞ'3ꢒ ꢎꢈꢊ
ꢆꢚ(ꢇ(ꢘ& ꢘꢞ (ꢉ$ꢊꢗꢊꢉ$ꢊꢉꢘꢇ& ꢗꢛꢞ-ꢛꢆꢙ ꢘꢈꢊ ꢞꢗꢊꢛꢆꢘ(ꢉ- %ꢗꢊꢊ$ ꢞ+
ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢆꢉ$ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢞ+ ꢊꢆ'ꢈ 'ꢈꢆꢉꢉꢊꢇ ꢙꢆ3ꢊ% ꢘꢈꢊ
ꢄꢋꢌꢍꢎ ꢆꢘꢘꢛꢆ'ꢘ(ꢑꢊ +ꢞꢛ %ꢗꢇ(ꢘ %ꢗꢊꢊ$ 'ꢈꢆꢉꢉꢊꢇ ꢆꢗꢗꢇ('ꢆꢘ(ꢞꢉ%
%ꢅ'ꢈ ꢆ% 'ꢇꢅ%ꢘꢊꢛꢊ$ ꢘꢊꢛꢙ(ꢉꢆꢇ %&%ꢘꢊꢙ%ꢒ
ꢎꢈꢊ $ꢆꢘꢆ ꢚꢅ% ꢚꢅ++ꢊꢛ ꢗꢛꢞꢑ($ꢊ% ꢘꢈꢊ (ꢉꢘꢊꢛ+ꢆ'ꢊ ꢚꢊꢘꢝꢊꢊꢉ ꢘꢈꢊ
(ꢉꢘꢊꢛꢉꢆꢇ ꢏꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ 'ꢈ(ꢗꢐ ꢆꢉ$ ꢊ!ꢘꢊꢛꢉꢆꢇ $ꢆꢘꢆ ꢚꢅ%ꢊ%ꢒ #ꢘ (%
'ꢞꢉꢘꢛꢞꢇꢇꢊ$ ꢚ& ꢘꢈꢊ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ 'ꢞꢉꢘꢛꢞꢇ ꢚꢇꢞ'3 ꢘꢞ ꢆꢇꢇꢞꢝ $ꢆꢘꢆ
ꢘꢛꢆꢉ%+ꢊꢛ% ꢘꢞ ꢘꢆ3ꢊ ꢗꢇꢆ'ꢊ ꢚꢊꢘꢝꢊꢊꢉ ꢘꢈꢊ ꢈꢞ%ꢘ ꢀ,ꢋ ꢆꢉ$ ꢘꢈꢊ
ꢄꢋꢌꢍꢎꢒ
B. OPERATION CONTROL BLOCK
ꢎꢈꢊ 'ꢞꢉꢘꢛꢞꢇ ꢇꢞ-(' ꢞ+ ꢘꢈꢊ ꢂꢗꢊꢛꢆꢘ(ꢞꢉ ꢀꢞꢉꢘꢛꢞꢇ ꢚꢇꢞ'3 ꢛꢊ'ꢊ(ꢑꢊ%
ꢞꢗꢊꢛꢆꢘ(ꢉ- 'ꢞꢙꢙꢆꢉ$% +ꢛꢞꢙ ꢘꢈꢊ ꢀ,ꢋ ꢆꢉ$ -ꢊꢉꢊꢛꢆꢘꢊ% ꢗꢛꢞꢗꢊꢛ
%(-ꢉꢆꢇ% ꢘꢞ ꢘꢈꢊ ꢑꢆꢛ(ꢞꢅ% %ꢊ'ꢘ(ꢞꢉ% ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎꢒ ꢎꢈꢊ
ꢂꢗꢊꢛꢆꢘ(ꢞꢉ ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3 +ꢅꢉ'ꢘ(ꢞꢉ% ꢆ% ꢘꢈꢊ ꢅ%ꢊꢛ (ꢉꢘꢊꢛ+ꢆ'ꢊ ꢘꢞ
ꢘꢈꢊ ꢛꢊ%ꢘ ꢞ+ ꢘꢈꢊ $ꢊꢑ('ꢊꢒ ꢃꢗꢊ'(+('ꢆꢇꢇ&" (ꢘ (% ꢛꢊ%ꢗꢞꢉ%(ꢚꢇꢊ +ꢞꢛ
ꢄꢋꢌꢍꢎ ꢍꢊ-(%ꢘꢊꢛ ꢌ$$ꢛꢊ%% ꢄꢊ'ꢞ$(ꢉ-" ꢆꢉ$ ꢀꢞꢙꢙꢆꢉ$
ꢄꢊ'ꢞ$(ꢉ-ꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ ꢆꢇꢇ 'ꢞꢙꢙꢆꢉ$% ꢘꢞ %ꢊꢘ ꢚꢆꢅ$ ꢛꢆꢘꢊ%"
ꢗꢆꢛ(ꢘ&" ꢞꢘꢈꢊꢛ 'ꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉ ꢗꢛꢞꢘꢞ'ꢞꢇ ꢗꢆꢛꢆꢙꢊꢘꢊꢛ%" %ꢘꢆꢛꢘ ꢞꢛ
%ꢘꢞꢗ ꢘꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢞꢛ ꢛꢊꢆ$(ꢉ- ꢆ C%ꢘꢆꢘꢅ% ꢛꢊ-(%ꢘꢊꢛD ꢘꢞ
ꢙꢞꢉ(ꢘꢞꢛ $ꢆꢘꢆ 'ꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉ ꢗꢊꢛ+ꢞꢛꢙꢆꢉ'ꢊ ꢙꢅ%ꢘ -ꢞ
ꢘꢈꢛꢞꢅ-ꢈ ꢘꢈꢊ ꢂꢗꢊꢛꢆꢘ(ꢞꢉ ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3ꢒ
ꢍꢊ'ꢊ(ꢑꢊꢛ $ꢆꢘꢆ (% Eꢅꢆ$ꢛꢅꢗꢇꢊ$ ꢚꢅ++ꢊꢛꢊ$ ꢆꢉ$ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ
$ꢆꢘꢆ (% $ꢅꢆꢇꢜꢚꢅ++ꢊꢛꢊ$ ꢑ(ꢆ ꢞꢉꢜ'ꢈ(ꢗ # ꢂ% (ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ
ꢙ(ꢉ(ꢙ(Iꢊ ꢘꢈꢊ ꢛ(%3 ꢞ+ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢞꢑꢊꢛꢛꢅꢉ ꢆꢉ$ ꢘꢞ ꢛꢊ$ꢅ'ꢊ
ꢞꢑꢊꢛꢈꢊꢆ$ (ꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ $ꢛ(ꢑꢊꢉ ꢆꢗꢗꢇ('ꢆꢘ(ꢞꢉ%ꢒ ꢎꢈꢊ ꢄꢋꢌꢍꢎ
ꢆꢇ%ꢞ ꢗꢛꢞꢑ($ꢊ%
ꢆ +ꢇꢞꢝ 'ꢞꢉꢘꢛꢞꢇ 'ꢆꢗꢆꢚ(ꢇ(ꢘ& ꢘꢞ (ꢉꢈ(ꢚ(ꢘ
ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉ +ꢛꢞꢙ ꢆ ꢛꢊꢙꢞꢘꢊ $ꢊꢑ('ꢊ ꢝꢈꢊꢉ ꢘꢈꢊ ꢚꢅ++ꢊꢛ ꢞ+ ꢘꢈꢊ
ꢛꢊ'ꢊ(ꢑ(ꢉ- ꢄꢋꢌꢍꢎ (% +ꢅꢇꢇ" ꢘꢈꢅ% ꢗꢛꢊꢑꢊꢉꢘ(ꢉ- ꢇꢞ%% ꢞ+ $ꢆꢘꢆꢒ
ꢎꢈꢊ ꢄꢋꢌꢍꢎ ꢆꢇ%ꢞ ꢗꢛꢞꢑ($ꢊ% ꢆ -ꢊꢉꢊꢛꢆꢇ ꢗꢅꢛꢗꢞ%ꢊ ꢔ/ ꢚ(ꢘ
'ꢞꢅꢉꢘꢊꢛ.ꢘ(ꢙꢊꢛ ꢏꢝꢈ('ꢈ ꢙꢆ& ꢆꢇ%ꢞ ꢚꢊ ꢅ%ꢊ$ ꢆ% ꢗꢛꢞ-ꢛꢆꢙꢙꢆꢚꢇꢊ
ꢚ(ꢘ ꢛꢆꢘꢊ -ꢊꢉꢊꢛꢆꢘꢞꢛ%ꢐ" ꢆ > ꢚ(ꢘ ꢙꢅꢇꢘ(ꢜꢗꢅꢛꢗꢞ%ꢊ (ꢉꢗꢅꢘ ꢗꢞꢛꢘ ꢆꢉ$ ꢆꢉ
= ꢚ(ꢘ ꢙꢅꢇꢘ(ꢜꢗꢅꢛꢗꢞ%ꢊ ꢞꢅꢘꢗꢅꢘ ꢗꢞꢛꢘ ꢏ+ꢞꢛ ꢘꢈꢊ <ꢕ ꢗ(ꢉ ꢄ#, ꢆꢉ$ <<
ꢗ(ꢉ ,9ꢀꢀ ꢗꢆ'3ꢆ-ꢊ% ꢞꢉꢇ&ꢐꢒ
ꢎꢈꢊ ꢂꢗꢊꢛꢆꢘ(ꢞꢉ ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3 ꢝ(ꢇꢇ 'ꢞꢉꢘꢛꢞꢇ ꢄꢋꢌꢍꢎ
ꢗꢊꢛ+ꢞꢛꢙꢆꢉ'ꢊ ꢚꢆ%ꢊ$ ꢅꢗꢞꢉ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- (ꢉꢗꢅꢘ %(-ꢉꢆꢇ%ꢒ
ꢌ$$ꢛꢊ%% #ꢉꢗꢅꢘ%" ꢌꢕ ꢜ ꢌ1
ꢜꢍꢄ
ꢜBꢍ
ꢜꢀꢃ
PRINCIPLES OF OPERATION
ꢍ2ꢃ2ꢎ
Figure 1 ꢗꢛꢊ%ꢊꢉꢘ% ꢆꢉ ꢞꢑꢊꢛꢆꢇꢇ ꢚꢇꢞ'3 $(ꢆ-ꢛꢆꢙ ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎꢒ
ꢌ% (ꢇꢇꢅ%ꢘꢛꢆꢘꢊ$ (ꢉ ꢘꢈꢊ ꢚꢇꢞ'3 $(ꢆ-ꢛꢆꢙ" ꢘꢈꢊ ꢄꢋꢌꢍꢎ 'ꢞꢉ%(%ꢘ% ꢞ+
ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- ꢙꢆMꢞꢛ +ꢅꢉ'ꢘ(ꢞꢉꢆꢇ ꢚꢇꢞ'3%4
Bꢈꢊꢉ ꢅ%(ꢉ- ꢘꢈꢊ /=ꢕꢕ +ꢆꢙ(ꢇ& ꢗꢛꢞ'ꢊ%%ꢞꢛ" ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢝ(ꢇꢇ
ꢛꢊEꢅ(ꢛꢊ %ꢞꢙꢊ -ꢇꢅꢊ ꢇꢞ-('ꢒ #ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢆ /=ꢕꢕ ꢆꢙ(ꢇ&
,ꢛꢞ'ꢊ%%ꢞꢛ ꢘꢞ ꢘꢈꢊ ꢄꢋꢌꢍꢎ 'ꢆꢉ ꢚꢊ ꢊꢆ%(ꢇ& ꢆ'ꢈ(ꢊꢑꢊ$ ꢚ&
(ꢉ'ꢇꢅ$(ꢉ- ꢆ %ꢙꢆꢇꢇ ꢆꢙꢞꢅꢉꢘ ꢞ+ ꢊ!ꢘꢊꢛꢉꢆꢇ ꢇꢞ-(' $ꢊꢑ('ꢊ%" ꢆ%
$ꢊꢗ('ꢘꢊ$ (ꢉ Figure 2ꢒ
ꢁ ꢄꢆꢘꢆ *ꢅ% *ꢅ++ꢊꢛ
ꢁ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢀꢞꢉꢘꢛꢞꢇ
ꢁ #ꢉꢗꢅꢘ ,ꢞꢛꢘ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢔꢓ
XR88C681
ꢜꢍ.B
ꢜBꢍ
2 'ꢇꢞ'3
ꢜꢍꢄ
ꢜꢍ2ꢃ2ꢎ
ꢍ2ꢃ2ꢎ
Figure 2. External Logic Circuitry required to interface a 6800 Family
Processor to the XR88C681 Device
B.1 DUART Register Addressing
ꢎꢈꢊ ꢆ$$ꢛꢊ%%(ꢉ- ꢞ+ ꢘꢈꢊ (ꢉꢘꢊꢛꢉꢆꢇ ꢛꢊ-(%ꢘꢊꢛ% ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ Table 1ꢒ Please note that some of the
registers are “Read Only” and others are “Write Only”. 2ꢆ'ꢈ 'ꢈꢆꢉꢉꢊꢇ (% ꢗꢛꢞꢑ($ꢊ$ ꢝ(ꢘꢈ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- $ꢊ$('ꢆꢘꢊ$
ꢏꢆ$$ꢛꢊ%%ꢆꢚꢇꢊꢐ ꢛꢊ-(%ꢘꢊꢛ%ꢒ
ꢁ ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ%
ꢁ ꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛ% ꢏꢁꢍꢔ ꢆꢉ$ ꢁꢍꢓꢐ
ꢁ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ%
ꢁ ꢀꢇꢞ'3 ꢃꢊꢇꢊ'ꢘ ꢍꢊ-(%ꢘꢊꢛ%
ꢁ ꢍꢊ'ꢊ(ꢑꢊꢛ 8ꢞꢇ$(ꢉ- ꢍꢊ-(%ꢘꢊꢛ ꢏꢍ8ꢍꢐ ꢆꢉ$ ꢎꢛꢆꢉ%ꢙ(ꢘ 8ꢞꢇ$(ꢉ- ꢍꢊ-(%ꢘꢊꢛ ꢏꢎ8ꢍꢐ
ꢌ$$(ꢘ(ꢞꢉꢆꢇꢇ&" ꢘꢈꢊ ꢄꢋꢌꢍꢎ 'ꢞꢉꢘꢆ(ꢉ% ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- ꢛꢊ-(%ꢘꢊꢛ% ꢘꢈꢆꢘ %ꢅꢗꢗꢞꢛꢘ.'ꢞꢉꢘꢛꢞꢇ ꢚꢞꢘꢈ 'ꢈꢆꢉꢉꢊꢇ%ꢒ
ꢁ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ
ꢁ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢆ%3 ꢍꢊ-(%ꢘꢊꢛ
ꢁ ꢁꢆ%3ꢊ$ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ
ꢁ #ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ ꢍꢊ-(%ꢘꢊꢛ
ꢁ ꢌꢅ!(ꢇ(ꢆꢛ& ꢀꢞꢉꢘꢛꢞꢇ ꢍꢊ-(%ꢘꢊꢛ
ꢌꢉ$ +(ꢉꢆꢇꢇ&" ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢆꢇ%ꢞ 'ꢞꢉꢘꢆ(ꢉ% ꢞꢘꢈꢊꢛ ꢛꢊ-(%ꢘꢊꢛ% ꢘꢈꢆꢘ %ꢅꢗꢗꢞꢛꢘ +ꢅꢉ'ꢘ(ꢞꢉ% ꢞꢘꢈꢊꢛ ꢘꢈꢆꢉ %ꢊꢛ(ꢆꢇ $ꢆꢘꢆ 'ꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉ" %ꢅ'ꢈ
ꢆ% ꢘꢈꢊ ꢗꢆꢛꢆꢇꢇꢊꢇ ꢗꢞꢛꢘ% ꢆꢉ$ ꢘꢈꢊ 'ꢞꢅꢉꢘꢊꢛ%.ꢘ(ꢙꢊꢛ%ꢒ
ꢁ ꢂ,ꢀꢍꢜ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢀꢞꢉꢘꢛꢞꢇ ꢍꢊ-(%ꢘꢊꢛ
ꢁ #,ꢀꢍ ꢜ #ꢉꢗꢅꢘ ,ꢞꢛꢘ ꢀꢞꢉ+(-ꢅꢛꢆꢘ(ꢞꢉ ꢍꢊ-(%ꢘꢊꢛ
ꢁ ꢀꢎꢋꢍ ꢜ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢋꢗꢗꢊꢛ *&ꢘꢊ ꢍꢊ-(%ꢘꢊꢛ
ꢁ ꢀꢎ9ꢍ ꢜ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ 9ꢞꢝꢊꢛ *&ꢘꢊ ꢍꢊ-(%ꢘꢊꢛ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢔ1
XR88C681
Address (Hex)
Read Mode Registers
Register Name Symbol
Write Mode Registers
Register Name
Symbol
ꢕꢕ
ꢕꢔ
ꢕꢓ
ꢕ1
ꢕ<
ꢕ6
ꢕ/
ꢕ>
ꢕ=
ꢕꢖ
ꢕꢌ
ꢕ*
ꢕꢀ
ꢕꢄ
ꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛ"
ꢀꢈꢆꢉꢉꢊꢇ ꢌ
ꢁꢍꢔꢌ" ꢁꢍꢓꢌ
ꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛ"
ꢀꢈꢆꢉꢉꢊꢇ ꢌ
ꢁꢍꢔꢌ" ꢁꢍꢓꢌ
ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ"
ꢀꢈꢆꢉꢉꢊꢇ ꢌ
ꢃꢍꢌ
ꢀꢇꢞ'3 ꢃꢊꢇꢊ'ꢘ ꢍꢊ-(%ꢘꢊꢛ"
ꢀꢈꢆꢉꢉꢊꢇ ꢌ
ꢀꢃꢍꢌ
ꢀꢍꢌ
ꢁꢆ%3ꢊ$ #ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ
ꢁ#ꢃꢍ
ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ ꢌ
ꢍ! 8ꢞꢇ$(ꢉ- ꢍꢊ-(%ꢘꢊꢛ"
ꢀꢈꢆꢉꢉꢊꢇ ꢌ
ꢍ8ꢍꢌ
#,ꢀꢍ
ꢎ! 8ꢞꢇ$(ꢉ- ꢍꢊ-(%ꢘꢊꢛ"
ꢀꢈꢆꢉꢉꢊꢇ ꢌ
ꢎ8ꢍꢌ
ꢌꢀꢍ
#ꢉꢗꢅꢘ ,ꢞꢛꢘ ꢀꢈꢆꢉ-ꢊ
ꢍꢊ-(%ꢘꢊꢛ
ꢌꢅ!(ꢇ(ꢆꢛ& ꢀꢞꢉꢘꢛꢞꢇ
ꢍꢊ-(%ꢘꢊꢛ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢘꢆꢘꢅ%
ꢍꢊ-(%ꢘꢊꢛ
#ꢃꢍ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢆ%3 ꢍꢊ-(%ꢘꢊꢛ
#ꢁꢍ
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢋꢗꢗꢊꢛ
*&ꢘꢊ ꢍꢊ-(%ꢘꢊꢛ
ꢀꢎꢋ
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ
ꢋꢗꢗꢊꢛ *&ꢘꢊ ꢍꢊ-(%ꢘꢊꢛ
ꢀꢎꢋ
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ 9ꢞꢝꢊꢛ
*&ꢘꢊ ꢍꢊ-(%ꢘꢊꢛ
ꢀꢎ9
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ 9ꢞꢝꢊꢛ
*&ꢘꢊ ꢍꢊ-(%ꢘꢊꢛ
ꢀꢎ9
ꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛ"
ꢀꢈꢆꢉꢉꢊꢇ *
ꢁꢍꢔ*" ꢁꢍꢓ*
ꢃꢍ*
ꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛ"
ꢀꢈꢆꢉꢉꢊꢇ *
ꢁꢍꢔ*" ꢁꢍꢓ*
ꢀꢃꢍ*
ꢀꢍ*
ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ"
ꢀꢈꢆꢉꢉꢊꢇ *
ꢀꢇꢞ'3 ꢃꢊꢇꢊ'ꢘ ꢍꢊ-(%ꢘꢊꢛ"
ꢀꢈꢆꢉꢉꢊꢇ *
ꢍ2ꢃ2ꢍ;2ꢄ
ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ"
ꢀꢈꢆꢉꢉꢊꢇ *
ꢍ! 8ꢞꢇ$(ꢉ- ꢍꢊ-(%ꢘꢊꢛ"
ꢀꢈꢆꢉꢉꢊꢇ *
ꢍ8ꢍ*
#;ꢍ
#,
ꢎ! 8ꢞꢇ$(ꢉ- ꢍꢊ-(%ꢘꢊꢛ"
ꢀꢈꢆꢉꢉꢊꢇ *
ꢎ8ꢍ*
#;ꢍ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ
ꢍꢊ-(%ꢘꢊꢛ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ
ꢍꢊ-(%ꢘꢊꢛ
#ꢉꢗꢅꢘ ,ꢞꢛꢘ
ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ
ꢀꢞꢉ+(-ꢅꢛꢆꢘ(ꢞꢉ ꢍꢊ-(%ꢘꢊꢛ
ꢏꢂ,ꢕ ꢜ ꢂ,>ꢐ
ꢂ,ꢀꢍ
ꢕ2
ꢕ
ꢃꢘꢆꢛꢘ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ
ꢀꢞꢙꢙꢆꢉ$
ꢃꢀꢀ
ꢃꢎꢀ
ꢃꢊꢘ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ *(ꢘ%
ꢀꢞꢙꢙꢆꢉ$
ꢃꢂ,*ꢀ
ꢀꢂ,*ꢀ
ꢃꢘꢞꢗ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ
ꢀꢞꢙꢙꢆꢉ$
ꢀꢇꢊꢆꢛ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ *(ꢘ%
ꢀꢞꢙꢙꢆꢉ$
Table 1. DUART Port and Register Addressing
Note: The shaded blocks are not Read/Write registers but are rather “Address-Triggered” Commands.
Table 1 (ꢉ$('ꢆꢘꢊ% ꢘꢈꢆꢘ ꢊꢆ'ꢈ 'ꢈꢆꢉꢉꢊꢇ (% ꢊEꢅ(ꢗꢗꢊ$ ꢝ(ꢘꢈ ꢘꢝꢞ ꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛ%ꢒ ꢌ%%ꢞ'(ꢆꢘꢊ$ ꢝ(ꢘꢈ ꢊꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ ꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛ
ꢗꢆ(ꢛ% (% ꢆ Cꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛD ꢗꢞ(ꢉꢘꢊꢛ ꢞꢛ ꢁꢍ ꢗꢞ(ꢉꢘꢊꢛꢒ ꢋꢗꢞꢉ 'ꢈ(ꢗ.%&%ꢘꢊꢙ ꢗꢞꢝꢊꢛ ꢅꢗ ꢞꢛ ꢍ2ꢃ2ꢎ ꢊꢆ'ꢈ ꢁꢍ ꢗꢞ(ꢉꢘꢊꢛ (% Cꢗꢞ(ꢉꢘ(ꢉ- ꢘꢞD
ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇ ꢁꢍꢔꢉ ꢛꢊ-(%ꢘꢊꢛꢒ ꢏPlease note that the suffix “n” is used at the end of many of the DUART registers symbols in
order to refer, generically, to either channels A or Bꢐꢒ 8ꢞꢝꢊꢑꢊꢛ" ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ ꢁꢍ ꢗꢞ(ꢉꢘꢊꢛ ꢝ(ꢇꢇ %ꢈ(+ꢘ +ꢛꢞꢙ ꢘꢈꢊ ꢆ$$ꢛꢊ%%
ꢞ+ ꢘꢈꢊ ꢁꢍꢔꢉ ꢛꢊ-(%ꢘꢊꢛ ꢘꢞ ꢘꢈꢆꢘ ꢞ+ ꢘꢈꢊ ꢁꢍꢓꢉ ꢛꢊ-(%ꢘꢊꢛ" (ꢙꢙꢊ$(ꢆꢘꢊꢇ& +ꢞꢇꢇꢞꢝ(ꢉ- ꢆꢉ& ꢍꢊꢆ$ ꢞꢛ Bꢛ(ꢘꢊ ꢆ''ꢊ%% ꢘꢞ ꢘꢈꢊ ꢁꢍꢔꢉ ꢛꢊ-(%ꢘꢊꢛꢒ
ꢎꢈꢊ ꢁꢍ ꢗꢞ(ꢉꢘꢊꢛ ꢝ(ꢇꢇ 'ꢞꢉꢘ(ꢉꢅꢊ ꢘꢞ Cꢗꢞ(ꢉꢘ ꢘꢞD ꢘꢈꢊ ꢁꢍꢓꢉ ꢛꢊ-(%ꢘꢊꢛ ꢅꢉꢘ(ꢇ ꢆ ꢈꢆꢛ$ꢝꢆꢛꢊ ꢛꢊ%ꢊꢘ ꢞ''ꢅꢛ% ꢞꢛ ꢅꢉꢘ(ꢇ ꢆ Cꢍ2ꢃ2ꢎ ꢁꢍ
,ꢂ#7ꢎ2ꢍD 'ꢞꢙꢙꢆꢉ$ ꢈꢆ% ꢚꢊꢊꢉ (ꢉꢑꢞ3ꢊ$ꢒ ꢎꢈꢊ Cꢍ2ꢃ2ꢎ ꢁꢍ ,ꢂ#7ꢎ2ꢍD 'ꢞꢙꢙꢆꢉ$ 'ꢆꢉ ꢚꢊ (%%ꢅꢊ$ ꢚ& ꢝꢛ(ꢘ(ꢉ- ꢘꢈꢊ
ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ $ꢆꢘꢆ ꢘꢞ ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ 'ꢈꢆꢉꢉꢊꢇH% ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢚꢞꢘꢈ ꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛ%" ꢝ(ꢘꢈ(ꢉ ꢆ -(ꢑꢊꢉ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢔ<
XR88C681
'ꢈꢆꢉꢉꢊꢇ" ꢈꢆꢑꢊ ꢘꢈꢊ %ꢆꢙꢊ ꢇꢞ-('ꢆꢇ ꢆ$$ꢛꢊ%%ꢒ ꢎꢈꢊ +ꢊꢆꢘꢅꢛꢊ% ꢆꢉ$ +ꢅꢉ'ꢘ(ꢞꢉ% ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢘꢈꢆꢘ ꢆꢛꢊ 'ꢞꢉꢘꢛꢞꢇꢇꢊ$ ꢚ& ꢘꢈꢊ ꢁꢞ$ꢊ
ꢍꢊ-(%ꢘꢊꢛ% ꢆꢛꢊ $(%'ꢅ%%ꢊ$ (ꢉ $ꢊꢘꢆ(ꢇ (ꢉ Section G.3ꢒ
B.2 Command Decoding
2ꢆ'ꢈ 'ꢈꢆꢉꢉꢊꢇ (% ꢊEꢅ(ꢗꢗꢊ$ ꢝ(ꢘꢈ ꢆ ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛꢒ #ꢉ -ꢊꢉꢊꢛꢆꢇ" ꢘꢈꢊ ꢛꢞꢇꢊ ꢞ+ ꢘꢈꢊ%ꢊ ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ% ꢆꢛꢊ ꢘꢞ
ꢊꢉꢆꢚꢇꢊ.$(%ꢆꢚꢇꢊ ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ" ꢊꢉꢆꢚꢇꢊ.$(%ꢆꢚꢇꢊ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ" ꢆꢇꢞꢉ- ꢝ(ꢘꢈ +ꢆ'(ꢇ(ꢘꢆꢘ(ꢉ- ꢆ %ꢊꢛ(ꢊ% ꢞ+ ꢞꢘꢈꢊꢛ ꢙ(%'ꢊꢇꢇꢆꢉꢊꢞꢅ%
'ꢞꢙꢙꢆꢉ$%ꢒ ꢎꢈꢊ ꢚ(ꢘ +ꢞꢛꢙꢆꢘ +ꢞꢛ ꢊꢆ'ꢈ ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ (% ꢗꢛꢊ%ꢊꢉꢘꢊ$ ꢈꢊꢛꢊꢝ(ꢘꢈꢒ
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Miscellaneous Commands
Enable/Disable
Enable/Disable
Transmitter
Receiver
ꢃꢊꢊ ꢞꢇꢇꢞꢝ(ꢉ- ꢎꢊ!ꢘ
ꢕꢕ J 7ꢞ ꢀꢈꢆꢉ-ꢊ
ꢕꢔ J 2ꢉꢆꢚꢇꢊ ꢍ!
ꢔꢕ J ꢄ(%ꢆꢚꢇꢊ ꢍ!
ꢕꢕ J 7ꢞ ꢀꢈꢆꢉ-ꢊ
ꢕꢔ J 2ꢉꢆꢚꢇꢊ ꢎ!
ꢔꢕ J ꢄ(%ꢆꢚꢇꢊ ꢎ!
ꢔꢔ J 7ꢞꢘ ꢑꢆꢇ($ ꢏ$ꢞ ꢉꢞꢘ ꢅ%ꢊꢐ
ꢔꢔ J 7ꢞꢘ ;ꢆꢇ($ ꢏꢄꢞ ꢉꢞꢘ ꢅ%ꢊꢐ
Table 2. (CRA, CRB) Bit Format for Command Registers of Channels A & B
ꢎꢈꢊ +ꢅꢉ'ꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢇꢞꢝꢊꢛ ꢉ(ꢚꢚꢇꢊ ꢞ+ ꢘꢈꢊ ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ% (% +ꢆ(ꢛꢇ& %ꢘꢛꢆ(-ꢈꢘꢜ+ꢞꢛꢝꢆꢛ$ꢒ ꢎꢈ(% ꢉ(ꢚꢚꢇꢊ (% ꢅ%ꢊ$ ꢘꢞ ꢊ(ꢘꢈꢊꢛ ꢊꢉꢆꢚꢇꢊ
ꢞꢛ $(%ꢆꢚꢇꢊ ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢆꢉ$.ꢞꢛ ꢍꢊ'ꢊ(ꢑꢊꢛꢒ
ꢎꢈꢊ ꢅꢗꢗꢊꢛ ꢉ(ꢚꢚꢇꢊ ꢞ+ ꢘꢈꢊ ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ (% ꢅ%ꢊ$ ꢘꢞ (ꢉꢑꢞ3ꢊ ꢆ %ꢊꢛ(ꢊ% ꢞ+ ꢙ(%'ꢊꢇꢇꢆꢉꢊꢞꢅ% 'ꢞꢙꢙꢆꢉ$%ꢒ Table 3 $ꢊ+(ꢉꢊ% ꢘꢈꢊ
'ꢞꢙꢙꢆꢉ$% ꢆ%%ꢞ'(ꢆꢘꢊ$ ꢝ(ꢘꢈ ꢘꢈꢊ ꢅꢗꢗꢊꢛ ꢉ(ꢚꢚꢇꢊ ꢞ+ ꢘꢈꢊ ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ%ꢒ Please note that the upper nibble commands
1
through B effects only the performance of Command Register’s Channelꢒ 8ꢞꢝꢊꢑꢊꢛ" 'ꢞꢙꢙꢆꢉ$% ꢀ ꢆꢉ$ ꢄ
16
ꢔ/ ꢔ/
ꢊ++ꢊ'ꢘ% %&%ꢘꢊꢙ ꢏꢞꢛ 'ꢈ(ꢗꢐ ꢇꢊꢑꢊꢇ ꢞꢗꢊꢛꢆꢘ(ꢞꢉꢒ
16
Bit 7
Bit 6
Bit 5
Bit 4
Description
ꢕ
ꢕ
ꢕ
ꢕ
ꢕ
ꢕ
ꢕ
ꢔ
Null Command.
Reset MRn Pointer. ꢀꢆꢅ%ꢊ% ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇH% ꢁꢍꢉ
ꢗꢞ(ꢉꢘꢊꢛ ꢘꢞ ꢗꢞ(ꢉꢘ ꢘꢞ ꢁꢍꢔꢉꢒ
ꢕ
ꢕ
ꢕ
ꢕ
ꢔ
ꢔ
ꢕ
ꢔ
Reset Receiver. ꢍꢊ%ꢊꢘ ꢘꢈꢊ (ꢉ$(ꢑ($ꢅꢆꢇ 'ꢈꢆꢉꢉꢊꢇ ꢛꢊꢜ
'ꢊ(ꢑꢊꢛ ꢆ% (+ ꢆ 8ꢆꢛ$ꢝꢆꢛꢊ ꢍꢊ%ꢊꢘ ꢈꢆ% ꢚꢊꢊꢉ ꢆꢗꢗꢇ(ꢊ$ꢒ
ꢎꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ (% $(%ꢆꢚꢇꢊ$ ꢆꢉ$ ꢘꢈꢊ # ꢂ (% +ꢇꢅ%ꢈꢊ$ꢒ
Reset Transmitter. ꢍꢊ%ꢊꢘ% ꢘꢈꢊ (ꢉ$(ꢑ($ꢅꢆꢇ 'ꢈꢆꢉꢉꢊꢇ
ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢆ% (+ ꢆ 8ꢆꢛ$ꢝꢆꢛꢊ ꢍꢊ%ꢊꢘ ꢈꢆ$ ꢚꢊꢊꢉ ꢆꢗꢗꢇ(ꢊ$ꢒ
ꢎꢈꢊ ꢎ5ꢄꢉ ꢞꢅꢘꢗꢅꢘ (% +ꢞꢛ'ꢊ$ ꢘꢞ ꢆ ꢈ(-ꢈ ꢇꢊꢑꢊꢇꢒ
Table 3. Miscellaneous Commands, Upper Nibble of all Command Registers,
Unless Otherwise Specified (Cont’d Next Page)
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢔ6
XR88C681
Bit 7
Bit 6
Bit 5
Bit 4
Description
ꢕ
ꢔ
ꢕ
ꢕ
Reset Error Status. ꢀꢇꢊꢆꢛ% ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊ$ *ꢛꢊꢆ3
ꢏꢍ*ꢐ" ,ꢆꢛ(ꢘ& 2ꢛꢛꢞꢛ ꢏ,2ꢐ" ꢛꢆꢙ(ꢉ- 2ꢛꢛꢞꢛ ꢏ 2ꢐ ꢆꢉ$
ꢂꢑꢊꢛꢛꢅꢉ 2ꢛꢛꢞꢛ ꢏꢂ2ꢐ %ꢘꢆꢘꢅ% ꢚ(ꢘ%" ꢃꢍN>41Oꢒ
ꢃꢗꢊ'(+('ꢆꢇꢇ&" (+ ꢘꢈꢊ 2ꢛꢛꢞꢛ ꢁꢞ$ꢊ" +ꢞꢛ ꢆ ꢗꢆꢛꢘ('ꢅꢇꢆꢛ 'ꢈꢆꢉꢜ
ꢉꢊꢇ (% %ꢊꢘ ꢆꢘ C*ꢇꢞ'3D 2ꢛꢛꢞꢛ ꢁꢞ$ꢊ" ꢘꢈ(% 'ꢞꢙꢙꢆꢉ$ ꢝ(ꢇꢇ
ꢛꢊ%ꢊꢘ ꢆꢇꢇ ꢞ+ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ 2ꢛꢛꢞꢛ #ꢉ$('ꢆꢘꢞꢛ% (ꢉ ꢘꢈꢊ ꢃꢘꢆꢘꢅ%
ꢍꢊ-(%ꢘꢊꢛꢒ #ꢉ ꢘꢈꢊ *ꢇꢞ'3 2ꢛꢛꢞꢛ ꢁꢞ$ꢊ" ꢞꢉ'ꢊ ꢊ(ꢘꢈꢊꢛ ꢆ ,2"
2" ꢂ2" ꢞꢛ ꢍ* ꢞ''ꢅꢛ%" ꢘꢈꢊ ꢊꢛꢛꢞꢛ ꢝ(ꢇꢇ 'ꢞꢉꢘ(ꢉꢅꢊ ꢘꢞ ꢚꢊ
+ꢇꢆ--ꢊ$ (ꢉ ꢘꢈꢊ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ" ꢅꢉꢘ(ꢇ ꢘꢈ(% 'ꢞꢙꢙꢆꢉ$ (%
(%%ꢅꢊ$ꢒ
#+ ꢘꢈꢊ 2ꢛꢛꢞꢛ ꢁꢞ$ꢊ" +ꢞꢛ ꢆ ꢗꢆꢛꢘ('ꢅꢇꢆꢛ 'ꢈꢆꢉꢉꢊꢇ (% %ꢊꢘ ꢘꢞ
Cꢀꢈꢆꢛꢆ'ꢘꢊꢛ 2ꢛꢛꢞꢛ ꢁꢞ$ꢊD" ꢘꢈꢊꢉ ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ
ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ +ꢞꢛ ,2" 2" ꢆꢉ$ ꢍ* ꢆꢛꢊ ꢛꢊ+ꢇꢊ'ꢘꢊ$ ꢞꢉ
ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢚ& 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢚꢆ%(%ꢒ #ꢉ ꢘꢈꢊ Cꢀꢈꢆꢛꢆ'ꢘꢊꢛ
2ꢛꢛꢞꢛ ꢁꢞ$ꢊD" ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ%ꢊ (ꢉ$('ꢆꢘꢞꢛ% (% ꢚꢆ%ꢊ$
ꢞꢉꢇ& ꢅꢗꢞꢉ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢘꢈꢆꢘ (% ꢆꢘ ꢘꢈꢊ ꢘꢞꢗ ꢞ+ ꢘꢈꢊ ꢍ8ꢍꢒ
ꢎꢈꢊ ꢂ2 (ꢉ$('ꢆꢘꢞꢛ (% ꢆꢇꢝꢆ&% ꢗꢛꢊ%ꢊꢉꢘꢊ$ ꢆ% ꢆ C*ꢇꢞ'3
2ꢛꢛꢞꢛ ꢁꢞ$ꢊD (ꢉ$('ꢆꢘꢞꢛ" ꢆꢉ$ ꢛꢊEꢅ(ꢛꢊ% ꢘꢈ(% 'ꢞꢙꢙꢆꢉ$ ꢘꢞ
ꢚꢊ ꢛꢊ%ꢊꢘꢒ
ꢕ
ꢕ
ꢔ
ꢔ
ꢕ
ꢔ
ꢔ
ꢕ
Reset Break Change Interrupt. ꢀꢇꢊꢆꢛ% ꢘꢈꢊ 'ꢈꢆꢉꢜ
ꢉꢊꢇH% ꢚꢛꢊꢆ3 'ꢈꢆꢉ-ꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢘꢆꢘꢅ% ꢚ(ꢘꢒ
Start Break. ꢞꢛ'ꢊ% ꢘꢈꢊ ꢎ5ꢄꢉ ꢞꢅꢘꢗꢅꢘ ꢇꢞꢝꢒ ꢎꢈꢊ
ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢙꢅ%ꢘ ꢚꢊ ꢊꢉꢆꢚꢇꢊ$ ꢘꢞ %ꢘꢆꢛꢘ ꢆ ꢚꢛꢊꢆ3ꢒ #+ ꢘꢈꢊ
ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% ꢊꢙꢗꢘ&" ꢘꢈꢊ %ꢘꢆꢛꢘ ꢞ+ ꢘꢈꢊ ꢚꢛꢊꢆ3 ꢙꢆ& ꢚꢊ
$ꢊꢇꢆ&ꢊ$ ꢅꢗ ꢘꢞ ꢘꢝꢞ ꢚ(ꢘ ꢘ(ꢙꢊ%ꢒ #+ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% ꢆ'ꢜ
ꢘ(ꢑꢊ" ꢘꢈꢊ ꢚꢛꢊꢆ3 ꢚꢊ-(ꢉ% ꢝꢈꢊꢉ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉ ꢞ+
ꢘꢈꢞ%ꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ% (ꢉ ꢘꢈꢊ ꢎ8ꢍ (% 'ꢞꢙꢗꢇꢊꢘꢊ$" ꢑ(Iꢒ"
ꢎ52ꢁ, ꢙꢅ%ꢘ ꢚꢊ ꢘꢛꢅꢊ ꢚꢊ+ꢞꢛꢊ ꢘꢈꢊ ꢚꢛꢊꢆ3 ꢝ(ꢇꢇ ꢚꢊ-(ꢉꢒ
ꢕ
ꢔ
ꢔ
ꢔ
Stop Break. ꢎꢈꢊ ꢎ5ꢄꢉ ꢇ(ꢉꢊ ꢝ(ꢇꢇ -ꢞ ꢈ(-ꢈ ꢝ(ꢘꢈ(ꢉ ꢘꢝꢞ
ꢚ(ꢘ ꢘ(ꢙꢊ%ꢒ ꢎ5ꢄꢉ ꢝ(ꢇꢇ ꢛꢊꢙꢆ(ꢉ ꢈ(-ꢈ +ꢞꢛ ꢞꢉꢊ ꢚ(ꢘ ꢘ(ꢙꢊ ꢚꢊꢜ
+ꢞꢛꢊ ꢘꢈꢊ ꢉꢊ!ꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛ" (+ ꢆꢉ&" (% ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ꢒ
ꢔ
ꢔ
ꢔ
ꢔ
ꢕ
ꢕ
ꢕ
ꢕ
ꢕ
ꢕ
ꢔ
ꢔ
ꢕ
ꢔ
ꢕ
ꢔ
Set Rx BRG Select Extend Bit. ꢃꢊꢘ% ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇH%
Cꢍꢊ'ꢊ(ꢑꢊꢛ *ꢍ0 ꢃꢊꢇꢊ'ꢘ 2!ꢘꢊꢉ$ *(ꢘD ꢘꢞ ꢔꢒ
Clear Rx BRG Select Extend Bit. ꢀꢇꢊꢆꢛ% ꢘꢈꢊ 'ꢈꢆꢉꢜ
ꢉꢊꢇH% Cꢍꢊ'ꢊ(ꢑꢊꢛ *ꢍ0 ꢃꢊꢇꢊ'ꢘ 2!ꢘꢊꢉ$ *(ꢘD ꢘꢞ ꢕꢒ
Set Tx BRG Select Extend Bit. ꢃꢊꢘ% ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇH%
Cꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ *ꢍ0 ꢃꢊꢇꢊ'ꢘ 2!ꢘꢊꢉ$ *(ꢘD ꢘꢞ ꢔꢒ
Clear Tx BRG Select Extend Bit. ꢀꢇꢊꢆꢛ% ꢘꢈꢊ 'ꢈꢆꢉꢜ
ꢉꢊꢇH% Cꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ *ꢍ0 ꢃꢊꢇꢊ'ꢘ 2!ꢘꢊꢉ$ *(ꢘD ꢘꢞ ꢕꢒ
Table 3. Miscellaneous Commands, Upper Nibble of all Command Registers,
Unless Otherwise Specified (Cont’d)
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢔ/
XR88C681
Bit 7
Bit 6
Bit 5
Bit 4
Description
ꢔ
ꢔ
ꢕ
ꢕ
Set Standby Mode (Channel A). Bꢈꢊꢉ ꢘꢈ(% 'ꢞꢙꢜ
ꢙꢆꢉ$ (% (ꢉꢑꢞ3ꢊ$ ꢑ(ꢆ ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢜ
ꢘꢊꢛ" ꢗꢞꢝꢊꢛ (% ꢛꢊꢙꢞꢑꢊ$ +ꢛꢞꢙ ꢊꢆ'ꢈ ꢞ+ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ%"
ꢛꢊ'ꢊ(ꢑꢊꢛ%" 'ꢞꢅꢉꢘꢊꢛ.ꢘ(ꢙꢊꢛ ꢆꢉ$ ꢆ$$(ꢘ(ꢞꢉꢆꢇ '(ꢛ'ꢅ(ꢘ% ꢘꢞ
ꢗꢇꢆ'ꢊ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (ꢉ ꢘꢈꢊ %ꢘꢆꢉ$ꢚ& ꢏꢞꢛ ꢇꢞꢝꢊꢛ ꢗꢞꢝꢊꢛꢐ
ꢙꢞ$ꢊꢒ Please note that this command effects the
operation of the entire chipꢒ 7ꢞꢛꢙꢆꢇ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ (% ꢛꢊꢜ
%ꢘꢞꢛꢊ$ ꢚ& ꢆ ꢈꢆꢛ$ꢝꢆꢛꢊ ꢛꢊ%ꢊꢘ ꢞꢛ ꢚ& (ꢉꢑꢞ3(ꢉ- ꢘꢈꢊ Cꢃ2ꢎ
ꢌꢀꢎ#;2 ꢁꢂꢄ2D 'ꢞꢙꢙꢆꢉ$ꢒ
Reset IUS Latch (Channel B). Bꢈꢊꢉ ꢘꢈ(% 'ꢞꢙꢙꢆꢉ$
(% (ꢉꢑꢞ3ꢊ$ ꢑ(ꢆ ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇ * ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ"
ꢆꢉ$ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ?ꢜꢙꢞ$ꢊ" (ꢘ 'ꢆꢅ%ꢊ%
ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘꢜꢋꢉ$ꢊꢛꢜꢃꢊꢛꢑ('ꢊꢏ#ꢋꢃꢐ ꢇꢆꢘ'ꢈ ꢘꢞ ꢚꢊ ꢛꢊ%ꢊꢘꢒ
ꢎꢈ(%" (ꢉ ꢘꢅꢛꢉ" ꢝ(ꢇꢇ 'ꢆꢅ%ꢊ ꢘꢈꢊ #2ꢂ ꢞꢅꢘꢗꢅꢘ ꢘꢞ ꢘꢞ--ꢇꢊ
Cꢈ(-ꢈDꢒ
ꢔ
ꢔ
ꢕ
ꢔ
Set Active Mode (Channel A). Bꢈꢊꢉ ꢘꢈ(% 'ꢞꢙꢜ
ꢙꢆꢉ$ (% (ꢉꢑꢞ3ꢊ$ ꢑ(ꢆ ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢜ
ꢘꢊꢛ" ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% ꢛꢊꢙꢞꢑꢊ$ +ꢛꢞꢙ ꢘꢈꢊ ꢃꢘꢆꢉ$ꢚ& ꢁꢞ$ꢊ
ꢆꢉ$ ꢛꢊ%ꢅꢙꢊ% ꢉꢞꢛꢙꢆꢇ ꢞꢗꢊꢛꢆꢘ(ꢞꢉꢒ
Set Z-Mode (Channel B). Bꢈꢊꢉ ꢘꢈ(% 'ꢞꢙꢙꢆꢉ$ (%
(ꢉꢑꢞ3ꢊ$ ꢑ(ꢆ ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇ * ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ" ꢘꢈꢊ
ꢄꢋꢌꢍꢎ (% 'ꢞꢉ$(ꢘ(ꢞꢉꢊ$ ꢘꢞ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊꢒ ꢞꢛ
ꢆ $ꢊꢘꢆ(ꢇꢊ$ $(%'ꢅ%%(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎH% ꢞꢗꢊꢛꢆꢘ(ꢞꢉ ꢝꢈ(ꢇꢊ
(ꢉ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊ" ,ꢇꢊꢆ%ꢊ %ꢊꢊ Section C.6.2ꢒ ꢏ7ꢞꢘ ꢆꢑꢆ(ꢇꢜ
ꢆꢚꢇꢊ +ꢞꢛ ꢘꢈꢊ ꢓ= ꢗ(ꢉ ꢄ#, ꢗꢆ'3ꢆ-ꢊ$ $ꢊꢑ('ꢊ%ꢐ
ꢔ
ꢔ
ꢔ
ꢔ
ꢔ
ꢔ
ꢕ
ꢔ
Reserved.
Reserved.
Table 3. Miscellaneous Commands, Upper Nibble of all Command Registers,
Unless Otherwise Specified (Cont’d)
#ꢉ ꢆ$$(ꢘ(ꢞꢉ ꢘꢞ ꢘꢈꢊ 'ꢞꢙꢙꢆꢉ$% ꢝꢈ('ꢈ ꢆꢛꢊ ꢆꢑꢆ(ꢇꢆꢚꢇꢊ ꢘꢈꢛꢞꢅ-ꢈ
ꢘꢈꢊ 'ꢞꢙꢙꢆꢉ$ ꢛꢊ-(%ꢘꢊꢛ%" ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢆꢇ%ꢞ ꢞ++ꢊꢛ%
Cꢌ$$ꢛꢊ%%ꢜꢎꢛ(--ꢊꢛꢊ$D 'ꢞꢙꢙꢆꢉ$%ꢒ ꢎꢈꢊ%ꢊ 'ꢞꢙꢙꢆꢉ$% ꢆꢛꢊ
ꢇ(%ꢘꢊ$ (ꢉ Table 1" Cꢄꢋꢌꢍꢎ ,ꢂꢍꢎ ꢌ7ꢄ ꢍ20#ꢃꢎ2ꢍ
ꢌꢄꢄꢍ2ꢃꢃ#70DL ꢆꢉ$ ꢆꢛꢊ +ꢅꢛꢘꢈꢊꢛ ($ꢊꢉꢘ(+(ꢊ$ ꢚ& ꢚꢊ(ꢉ-
C%ꢈꢆ$ꢊ$D (ꢉ Table 1ꢒ ꢃꢗꢊ'(+('ꢆꢇꢇ&" ꢘꢈꢊ%ꢊ 'ꢞꢙꢙꢆꢉ$% ꢆꢛꢊ4
ꢞꢉꢇ& ꢘꢈ(ꢉ- ꢘꢈꢆꢘ ꢝ(ꢇꢇ ꢈꢆꢗꢗꢊꢉ" (ꢉ ꢛꢊ%ꢗꢞꢉ%ꢊ ꢘꢞ ꢘꢈ(% ꢗꢛꢞ'ꢊ$ꢅꢛꢊ
(% ꢘꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢝ(ꢇꢇ (ꢉ(ꢘ(ꢆꢘꢊ 'ꢞꢅꢉꢘ(ꢉ-ꢒ ꢞꢛ ꢆ $ꢊꢘꢆ(ꢇꢊ$
$(%'ꢅ%%(ꢞꢉ (ꢉꢘꢞ ꢘꢈꢊ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ" ꢗꢇꢊꢆ%ꢊ
%ꢊꢊ Section D.2ꢒ
ꢌꢉꢞꢘꢈꢊꢛ ꢊ!ꢆꢙꢗꢇꢊ ꢞ+ ꢆꢉ ꢌ$$ꢛꢊ%%ꢜꢎꢛ(--ꢊꢛꢊ$ 'ꢞꢙꢙꢆꢉ$% (%
ꢘꢈꢊ Cꢃ2ꢎ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃD ꢀꢞꢙꢙꢆꢉ$ꢒ ꢎꢈ(%
'ꢞꢙꢙꢆꢉ$ (% (ꢉꢑꢞ3ꢊ$ ꢚ& ꢗꢊꢛ+ꢞꢛꢙ(ꢉ- ꢆ ꢝꢛ(ꢘꢊ ꢞ+ $ꢆꢘꢆ ꢘꢞ
ꢁ ꢃꢎꢌꢍꢎ ꢀꢂꢋ7ꢎ2ꢍ.ꢎ#ꢁ2ꢍ ꢀꢂꢁꢁꢌ7ꢄ
ꢁ ꢃꢎꢂ, ꢀꢂꢋ7ꢎ2ꢍ.ꢎ#ꢁ2ꢍ ꢀꢂꢁꢁꢌ7ꢄ
ꢁ ꢃ2ꢎ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃ ꢀꢂꢁꢁꢌ7ꢄ
ꢁ ꢀ92ꢌꢍ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃ ꢀꢂꢁꢁꢌ7ꢄ
ꢄꢋꢌꢍꢎ ꢆ$$ꢛꢊ%% ꢕ2
ꢒ
ꢔ/
Bꢈꢊꢉ ꢘꢈꢊ ꢅ%ꢊꢛ (ꢉꢑꢞ3ꢊ% ꢘꢈ(%
'ꢞꢙꢙꢆꢉ$" ꢈꢊ.%ꢈꢊ (% %ꢊꢘꢘ(ꢉ- 'ꢊꢛꢘꢆ(ꢉ ꢚ(ꢘ% ꢏꢘꢞ CꢔDꢐ ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ
ꢂ,ꢍ ꢏꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢍꢊ-(%ꢘꢊꢛꢐꢒ ꢌꢇꢇ ꢞꢘꢈꢊꢛ ꢚ(ꢘ%" ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢂ,ꢍ
ꢏꢉꢞꢘ %ꢗꢊ'(+(ꢊ$ ꢘꢞ ꢚꢊ %ꢊꢘꢐ" ꢆꢛꢊ ꢉꢞꢘ 'ꢈꢆꢉ-ꢊ$ꢒ ꢎꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ
ꢞꢅꢘꢗꢅꢘ ꢗꢞꢛꢘ ꢗ(ꢉ% ꢆꢛꢊ 'ꢞꢙꢗꢇꢊꢙꢊꢉꢘ% ꢞ+ ꢘꢈꢊ (ꢉ$(ꢑ($ꢅꢆꢇ ꢚ(ꢘ%
ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢂ,ꢍꢒ 8ꢊꢉ'ꢊ" (+ ꢂ,ꢍNꢕO (% %ꢊꢘ ꢘꢞ CꢔD" ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+
ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- ꢞꢅꢘꢗꢅꢘ ꢗꢞꢛꢘ ꢗ(ꢉ" ꢂ,ꢕ" (% ꢉꢞꢝ %ꢊꢘ ꢘꢞ ꢆ
ꢇꢞ-(' CꢕDꢒ ꢀꢞꢉ%ꢊEꢅꢊꢉꢘꢇ&" ꢞꢉꢊ 'ꢆꢉ ꢘꢈ(ꢉ3 ꢞ+ ꢘꢈꢊ Cꢃ2ꢎ
ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃD 'ꢞꢙꢙꢆꢉ$ ꢆ% ꢘꢈꢊ Cꢀ92ꢌꢍ
ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ ,#7ꢃD 'ꢞꢙꢙꢆꢉ$ꢒ ꢞꢛ ꢆ ꢙꢞꢛꢊ $ꢊꢘꢆ(ꢇꢊ$
$(%'ꢅ%%(ꢞꢉ (ꢉꢘꢞ ꢘꢈꢊ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ%" ꢗꢇꢊꢆ%ꢊ
%ꢊꢊ Section Fꢒ
2ꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ 'ꢞꢙꢙꢆꢉ$% ꢆꢛꢊ (ꢉꢑꢞ3ꢊ$ ꢚ& ꢊ(ꢘꢈꢊꢛ ꢛꢊꢆ$(ꢉ- ꢞꢛ
ꢝꢛ(ꢘ(ꢉ- $ꢆꢘꢆ ꢘꢞ ꢘꢈꢊ(ꢛ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- ꢄꢋꢌꢍꢎ ꢆ$$ꢛꢊ%%ꢊ% ꢆ%
%ꢗꢊ'(+(ꢊ$ (ꢉ Table 1ꢒ
ꢞꢛ 2!ꢆꢙꢗꢇꢊ4
ꢎꢈꢊ ꢃꢎꢌꢍꢎ ꢀꢂꢋ7ꢎ2ꢍ.ꢎ#ꢁ2ꢍ ꢀꢂꢁꢁꢌ7ꢄ (% (ꢉꢑꢞ3ꢊ$ ꢚ&
ꢘꢈꢊ ꢗꢛꢞ'ꢊ$ꢅꢛꢊ ꢞ+ ꢛꢊꢆ$(ꢉ- ꢄꢋꢌꢍꢎ ꢆ$$ꢛꢊ%% ꢕ2 ꢒ Please
ꢔ/
note that this “Read Operation” will not result in placing
the contents of a DUART register on the data bus. ꢎꢈꢊ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢔ>
XR88C681
C. INTERRUPT CONTROL BLOCK
ꢁ ꢍꢊ'ꢊ(ꢑꢊ # ꢂ ꢌ ꢞꢛ * ꢅꢇꢇ
ꢁ ꢃꢘꢆꢛꢘ ꢞꢛ 2ꢉ$ ꢞ+ ꢍꢊ'ꢊ(ꢑꢊ$ *ꢛꢊꢆ3 (ꢉ ꢀꢈꢆꢉꢉꢊꢇ% ꢌ ꢞꢛ *
ꢁ 2ꢉ$ ꢞ+ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢀꢞꢅꢉꢘ ꢍꢊꢆ'ꢈꢊ$
ꢁ ꢀꢈꢆꢉ-ꢊ ꢞ+ ꢃꢘꢆꢘꢊ ꢞꢉ (ꢉꢗꢅꢘ ꢗ(ꢉ%" #,ꢕ" #,ꢔ" #,ꢓ" #,1
ꢎꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3 ꢆꢇꢇꢞꢝ% ꢘꢈꢊ ꢅ%ꢊꢛ ꢘꢞ ꢆꢗꢗꢇ& ꢘꢈꢊ
ꢄꢋꢌꢍꢎ (ꢉ ꢆꢉ C#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢄꢛ(ꢑꢊꢉD ꢊꢉꢑ(ꢛꢞꢉꢙꢊꢉꢘꢒ ꢎꢈꢊ
ꢄꢋꢌꢍꢎ (ꢉ'ꢇꢅ$ꢊ% ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ ꢞꢅꢘꢗꢅꢘ %(-ꢉꢆꢇ
ꢏꢜ#7ꢎꢍꢐ" ꢝꢈ('ꢈ ꢙꢆ& ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ ꢚꢊ ꢆ%%ꢊꢛꢘꢊ$ ꢅꢗꢞꢉ
ꢘꢈꢊ ꢞ''ꢅꢛꢛꢊꢉ'ꢊ ꢞ+ ꢆꢉ& ꢞ+ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- ꢊꢑꢊꢉꢘ%4
ꢎꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3 'ꢞꢉ%(%ꢘ% ꢞ+ ꢆꢉ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢘꢆꢘꢅ%
ꢍꢊ-(%ꢘꢊꢛ% ꢏ#ꢃꢍꢐ" ꢆꢉ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢆ%3 ꢍꢊ-(%ꢘꢊꢛ% ꢏ#ꢁꢍꢐ" ꢆ
ꢁꢆ%3ꢊ$ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ% ꢏꢁ#ꢃꢍꢐ ꢆꢉ$ ꢆꢉ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ ꢍꢊ-(%ꢘꢊꢛ ꢏ#;ꢍꢐꢒ Table 4 ꢇ(%ꢘ% ꢘꢈꢊ%ꢊ
ꢛꢊ-(%ꢘꢊꢛ%" ꢘꢈꢊ(ꢛ ꢆ$$ꢛꢊ%% ꢇꢞ'ꢆꢘ(ꢞꢉ ꢏꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢄꢋꢌꢍꢎꢐꢒ
ꢁ ꢎꢛꢆꢉ%ꢙ(ꢘ 8ꢞꢇ$ ꢍꢊ-(%ꢘꢊꢛ ꢌ ꢞꢛ * ꢍꢊꢆ$&
ꢁ ꢍꢊ'ꢊ(ꢑꢊ 8ꢞꢇ$ ꢍꢊ-(%ꢘꢊꢛ ꢌ ꢞꢛ * ꢍꢊꢆ$&
Register
Description
#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢆ%3 ꢍꢊ-(%ꢘꢊꢛ
ꢁꢆ%3ꢊ$ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ ꢍꢊ-(%ꢘꢊꢛ
Address Location
(in DUART Address Space)
#ꢃꢍ
#ꢁꢍ
ꢁ#ꢃꢍ
#;ꢍ
ꢕ6ꢔ/ ꢏꢍꢊꢆ$ ꢂꢉꢇ&ꢐ
ꢕ6ꢔ/ ꢏBꢛ(ꢘꢊ ꢂꢉꢇ&ꢐ
ꢕꢓꢔ/ ꢏꢍꢊꢆ$ ꢂꢉꢇ&ꢐ
ꢕꢀꢔ/
Table 4. Listing and Brief Description of Interrupt System Registers
ꢎꢈꢊ ꢛꢞꢇꢊ ꢆꢉ$ ꢗꢅꢛꢗꢞ%ꢊ ꢞ+ ꢊꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ ꢛꢊ-(%ꢘꢊꢛ% ꢆꢛꢊ
$ꢊ+(ꢉꢊ$ ꢈꢊꢛꢊꢒ
ꢞ''ꢅꢛꢛ(ꢉ-ꢒ #ꢉ -ꢊꢉꢊꢛꢆꢇ" ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ #ꢃꢍ ꢝ(ꢇꢇ (ꢉ$('ꢆꢘꢊ
ꢘꢞ ꢘꢈꢊ ꢗꢛꢞ'ꢊ%%ꢞꢛ" ꢘꢈꢊ %ꢞꢅꢛ'ꢊ ꢞꢛ ꢘꢈꢊ ꢛꢊꢆ%ꢞꢉ +ꢞꢛ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢍꢊEꢅꢊ%ꢘ +ꢛꢞꢙ ꢘꢈꢊ ꢄꢋꢌꢍꢎꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢆꢉ& (ꢉꢘꢊꢛꢛꢅꢗꢘ
%ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ +ꢞꢛ ꢘꢈꢊ ꢄꢋꢌꢍꢎ %ꢈꢞꢅꢇ$ ꢚꢊ-(ꢉ ꢚ& ꢛꢊꢆ$(ꢉ-
ꢊ(ꢘꢈꢊꢛ ꢘꢈ(% ꢛꢊ-(%ꢘꢊꢛ ꢞꢛ ꢘꢈꢊ ꢁ#ꢃꢍ ꢏꢁꢆ%3ꢊ$ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢘꢆꢘꢅ%
ꢍꢊ-(%ꢘꢊꢛꢐꢒ ꢎꢈꢊ ꢚ(ꢘꢜ+ꢞꢛꢙꢆꢘ ꢞ+ ꢘꢈꢊ #ꢃꢍ (% ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ
Table 54
C.1 Interrupt Status Registers (ISR)
ꢎꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ #ꢃꢍ (ꢉ$('ꢆꢘꢊ% ꢘꢈꢊ %ꢘꢆꢘꢅ% ꢞ+ ꢆꢇꢇ ꢗꢞꢘꢊꢉꢘ(ꢆꢇ
(ꢉꢘꢊꢛꢛꢅꢗꢘ 'ꢞꢉ$(ꢘ(ꢞꢉ%ꢒ #+ ꢆꢉ& ꢚ(ꢘ% ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ%ꢊ ꢛꢊ-(%ꢘꢊꢛ% ꢆꢛꢊ
ꢘꢞ--ꢇꢊ$ Cꢈ(-ꢈD" ꢘꢈꢊꢉ ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- 'ꢞꢉ$(ꢘ(ꢞꢉ ꢈꢆ% ꢞꢛ (%
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Input Port
Change
Delta Break
B
RXRDY/
FFULLB
TXRDYB
Counter
Ready
Delta Break
A
RXRDY/
FFULLA
TXRDYA
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
Table 5. ISR Bit Format
ꢎꢈꢊ $ꢊ+(ꢉ(ꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢙꢊꢆꢉ(ꢉ- ꢚꢊꢈ(ꢉ$ ꢊꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ ꢚ(ꢘ% (%
ꢗꢛꢊ%ꢊꢉꢘꢊ$ ꢈꢊꢛꢊꢒ
ꢁ ꢎꢈꢊ (ꢉ$(ꢑ($ꢅꢆꢇ #ꢉꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ ꢘꢈꢆꢘ 'ꢈꢆꢉ-ꢊ$ %ꢘꢆꢘꢊ
ꢁ ꢎꢈꢊ +(ꢉꢆꢇ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ ꢙꢞꢉ(ꢘꢞꢛꢊ$ (ꢉꢗꢅꢘ ꢗꢞꢛꢘ%" +ꢞꢇꢇꢞꢝ(ꢉ-
ꢘꢈꢊ ꢀꢈꢆꢉ-ꢊ ꢞ+ ꢃꢘꢆꢘꢊꢒ
ꢞꢛ ꢆ $ꢊꢘꢆ(ꢇꢊ$ $ꢊ%'ꢛ(ꢗꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ #,ꢀꢍ" %ꢊꢊ Section Fꢒ
ISR[7]: Input Port Change of State
Please note that in order to enable this Interrupt
Condition, the user must do two things:
#+ ꢘꢈ(% ꢚ(ꢘ (% ꢆꢘ ꢆ ꢇꢞ-(' CꢔD" ꢘꢈꢊꢉ ꢆ 'ꢈꢆꢉ-ꢊ ꢞ+ %ꢘꢆꢘꢊ ꢝꢆ%
$ꢊꢘꢊ'ꢘꢊ$ ꢆꢘ #ꢉꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ% #,ꢕ ꢜ #,1ꢒ ꢎꢈꢊ ꢅ%ꢊꢛ ꢝꢞꢅꢇ$
%ꢊꢛꢑ('ꢊ ꢘꢈ(% (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢚ& ꢛꢊꢆ$(ꢉ- ꢘꢈꢊ #,ꢀꢍ ꢏ(+ #ꢃꢍN>O J ꢔꢐꢒ
#ꢃꢍN>O (% 'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ ꢀ,ꢋ ꢈꢆ% ꢛꢊꢆ$ ꢘꢈꢊ #ꢉꢗꢅꢘ ,ꢞꢛꢘ
ꢀꢞꢉ+(-ꢅꢛꢆꢘ(ꢞꢉ ꢍꢊ-(%ꢘꢊꢛ ꢏ#,ꢀꢍꢐꢒ *& ꢛꢊꢆ$(ꢉ- ꢘꢈꢊ #,ꢀꢍ" ꢘꢈꢊ
ꢅ%ꢊꢛ ꢝ(ꢇꢇ $ꢊꢘꢊꢛꢙ(ꢉꢊ4
ꢔꢒ Bꢛ(ꢘꢊ ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ $ꢆꢘꢆ ꢘꢞ ꢘꢈꢊ ꢇꢞꢝꢊꢛ ꢉ(ꢚꢚꢇꢊ ꢞ+ ꢘꢈꢊ
ꢌꢅ!(ꢇ(ꢆꢛ& ꢀꢞꢉꢘꢛꢞꢇ ꢍꢊ-(%ꢘꢊꢛ" ꢌꢀꢍN14ꢕOꢒ #ꢉ ꢘꢈ(% %ꢘꢊꢗ" ꢘꢈꢊ
ꢅ%ꢊꢛ (% %ꢗꢊ'(+&(ꢉ- ꢝꢈ('ꢈ #ꢉꢗꢅꢘ ,(ꢉ% %ꢈꢞꢅꢇ$ ꢘꢛ(--ꢊꢛ ꢆꢉ
C#ꢉꢗꢅꢘ ,ꢞꢛꢘ ꢀꢈꢆꢉ-ꢊD #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢔ=
XR88C681
ꢓꢒ Bꢛ(ꢘꢊ ꢆ ꢇꢞ-(' CꢔD ꢘꢞ #ꢁꢍN>Oꢒ
ꢀꢈꢆꢛꢆ'ꢘꢊꢛ% ꢇꢞꢆ$ꢊ$ (ꢉꢘꢞ ꢎ8ꢍ* ꢝꢈ(ꢇꢊ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (%
$(%ꢆꢚꢇꢊ$ ꢝ(ꢇꢇ ꢉꢞꢘ ꢚꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ꢒ
ISR[6] Delta Break Indicator - Channel B
ISR[3] Counter Ready
Bꢈꢊꢉ ꢘꢈ(% ꢚ(ꢘ (% %ꢊꢘ" (ꢘ (ꢉ$('ꢆꢘꢊ% ꢘꢈꢆꢘ ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇ *
ꢛꢊ'ꢊ(ꢑꢊꢛ ꢈꢆ% $ꢊꢘꢊ'ꢘꢊ$ ꢘꢈꢊ ꢚꢊ-(ꢉꢉ(ꢉ- ꢞꢛ ꢊꢉ$ ꢞ+ ꢆ ꢛꢊ'ꢊ(ꢑꢊ$
ꢚꢛꢊꢆ3 ꢏꢍ*ꢐꢒ ꢎꢈ(% ꢚ(ꢘ (% 'ꢇꢊꢆꢛꢊ$ ꢏꢞꢛ ꢛꢊ%ꢊꢘꢐ ꢝꢈꢊꢉ ꢘꢈꢊ ꢀ,ꢋ
#ꢉ ꢘꢈꢊ ꢎ#ꢁ2ꢍ ꢙꢞ$ꢊ" ꢘꢈꢊ ꢀ.ꢎ ꢏꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛꢐ ꢝ(ꢇꢇ %ꢊꢘ
#ꢃꢍN1O ꢞꢉ'ꢊ ꢊꢆ'ꢈ '&'ꢇꢊ ꢞ+ ꢘꢈꢊ ꢛꢊ%ꢅꢇꢘꢆꢉꢘ %Eꢅꢆꢛꢊ ꢝꢆꢑꢊ
ꢏꢆꢑꢆ(ꢇꢆꢚꢇꢊ ꢆꢘ ꢘꢈꢊ ꢂ,1 ꢗ(ꢉꢐꢒ #ꢃꢍN1O ꢝ(ꢇꢇ ꢚꢊ 'ꢇꢊꢆꢛꢊ$ ꢚ&
(ꢉꢑꢞ3(ꢉ- ꢘꢈꢊ Cꢃꢎꢂ, ꢀꢂꢋ7ꢎ2ꢍD 'ꢞꢙꢙꢆꢉ$ꢒ *ꢊꢆꢛ (ꢉ ꢙ(ꢉ$"
ꢘꢈꢆꢘ (ꢉ ꢘꢈꢊ ꢎ#ꢁ2ꢍ ꢙꢞ$ꢊ" ꢘꢈꢊ Cꢃꢎꢂ, ꢀꢂꢋ7ꢎ2ꢍD
'ꢞꢙꢙꢆꢉ$ ꢝ(ꢇꢇ ꢉꢞꢘ %ꢘꢞꢗ ꢘꢈꢊ ꢀ.ꢎꢒ
(ꢉꢑꢞ3ꢊ%
ꢆ
'ꢈꢆꢉꢉꢊꢇ
*
Cꢍ2ꢃ2ꢎ *ꢍ2ꢌ: ꢀ8ꢌ702
ꢞꢛ ꢙꢞꢛꢊ
(ꢉ+ꢞꢛꢙꢆꢘ(ꢞꢉ (ꢉꢘꢞ ꢘꢈꢊ ꢄꢋꢌꢍꢎH% ꢛꢊ%ꢗꢞꢉ%ꢊ ꢘꢞ ꢆ *ꢍ2ꢌ:
#7ꢎ2ꢍꢍꢋ,ꢎD 'ꢞꢙꢙꢆꢉ$ ꢏ%ꢊꢊ Table 3ꢐꢒ
'ꢞꢉ$(ꢘ(ꢞꢉ" ꢗꢇꢊꢆ%ꢊ %ꢊꢊ Section G.2ꢒ
#ꢉ ꢘꢈꢊ ꢀꢂꢋ7ꢎ2ꢍ ꢙꢞ$ꢊ" ꢘꢈ(% ꢚ(ꢘ (% %ꢊꢘ ꢝꢈꢊꢉ ꢘꢈꢊ 'ꢞꢅꢉꢘꢊꢛ
ꢛꢊꢆ'ꢈꢊ% ꢘꢈꢊ ꢘꢊꢛꢙ(ꢉꢆꢇ 'ꢞꢅꢉꢘ ꢏꢕꢕꢕꢕ ꢐ ꢆꢉ$ (% 'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ
ꢔ/
ISR[5] RXRDY/FFULL B - Channel B Receiver Ready
or FIFO Full
ꢘꢈꢊ 'ꢞꢅꢉꢘꢊꢛ (% %ꢘꢞꢗꢗꢊ$ ꢚ& ꢆ Cꢃꢎꢂ, ꢀꢂꢋ7ꢎ2ꢍD
'ꢞꢙꢙꢆꢉ$ꢒ Bꢈꢊꢉ ꢘꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ (% (ꢉ ꢘꢈꢊ ꢀꢂꢋ7ꢎ2ꢍ
ꢁꢞ$ꢊ" ꢘꢈꢊ Cꢃꢎꢂ, ꢀꢂꢋ7ꢎ2ꢍD 'ꢞꢙꢙꢆꢉ$ ꢝ(ꢇꢇ %ꢘꢞꢗ ꢘꢈꢊ
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛꢒ
ꢎꢈꢊ +ꢅꢉ'ꢘ(ꢞꢉ ꢞ+ ꢘꢈ(% ꢚ(ꢘ (% %ꢊꢇꢊ'ꢘꢊ$ ꢚ& ꢗꢛꢞ-ꢛꢆꢙꢙ(ꢉ-
ꢁꢍꢔ*N/Oꢒ #+ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢆ% ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢍꢊꢆ$&
(ꢉ$('ꢆꢘꢞꢛ ꢏꢍ5ꢍꢄG*ꢐ" (ꢘ (ꢉ$('ꢆꢘꢊ% ꢘꢈꢆꢘ ꢆꢘ ꢇꢊꢆ%ꢘ ꢞꢉꢊ
'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢞ+ $ꢆꢘꢆ (% (ꢉ ꢍ8ꢍ* ꢆꢉ$ (% ꢛꢊꢆ$& ꢘꢞ ꢚꢊ ꢛꢊꢆ$ ꢚ& ꢘꢈꢊ
ꢀ,ꢋꢒ ꢎꢈ(% ꢚ(ꢘ (% %ꢊꢘ ꢝꢈꢊꢉ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢘꢛꢆꢉ%+ꢊꢛꢛꢊ$ +ꢛꢞꢙ
ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ %ꢈ(+ꢘ ꢛꢊ-(%ꢘꢊꢛ ꢘꢞ ꢍ8ꢍ* ꢆꢉ$ (% 'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ
ꢘꢈꢊ ꢀ,ꢋ ꢛꢊꢆ$% ꢘꢈꢊ ꢍ8ꢍ*ꢒ #+ ꢘꢈꢊꢛꢊ ꢆꢛꢊ %ꢘ(ꢇꢇ ꢙꢞꢛꢊ
'ꢈꢆꢛꢆ'ꢘꢊꢛ% (ꢉ ꢍ8ꢍ* ꢆ+ꢘꢊꢛ ꢘꢈꢊ ꢛꢊꢆ$ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ" ꢘꢈꢊ ꢚ(ꢘ ꢝ(ꢇꢇ ꢚꢊ
%ꢊꢘ ꢆ-ꢆ(ꢉ ꢆ+ꢘꢊꢛ ꢍ8ꢍ* (% Cꢗꢞꢗꢗꢊ$Dꢒ
ISR[2]: Delta Break A - Channel A Change in Break
ꢌ%%ꢊꢛꢘ(ꢞꢉ ꢞ+ ꢘꢈ(% ꢚ(ꢘ (ꢉ$('ꢆꢘꢊ% ꢘꢈꢆꢘ ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇ ꢌ ꢛꢊ'ꢊ(ꢑꢊꢛ
ꢈꢆ% $ꢊꢘꢊ'ꢘꢊ$ ꢘꢈꢊ ꢚꢊ-(ꢉꢉ(ꢉ- ꢞ+ ꢞꢛ ꢘꢈꢊ ꢊꢉ$ ꢞ+ ꢆ ꢛꢊ'ꢊ(ꢑꢊ$
ꢚꢛꢊꢆ3 ꢏꢍ*ꢐꢒ ꢎꢈ(% ꢚ(ꢘ (% 'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ ꢀ,ꢋ (ꢉꢑꢞ3ꢊ% ꢆ
'ꢈꢆꢉꢉꢊꢇ ꢌ Cꢍ2ꢃ2ꢎ *ꢍ2ꢌ: ꢀ8ꢌ702 #7ꢎ2ꢍꢍꢋ,ꢎD
'ꢞꢙꢙꢆꢉ$ꢒ ꢞꢛ ꢙꢞꢛꢊ (ꢉ+ꢞꢛꢙꢆꢘ(ꢞꢉ (ꢉꢘꢞ ꢘꢈꢊ ꢄꢋꢌꢍꢎH%
ꢛꢊ%ꢗꢞꢉ%ꢊ ꢘꢞ ꢆ *ꢍ2ꢌ: 'ꢞꢉ$(ꢘ(ꢞꢉ" ꢗꢇꢊꢆ%ꢊ %ꢊꢊ Section G.2ꢒ
#+ ꢘꢈ(% ꢚ(ꢘ (% ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢆ% # ꢂ +ꢅꢇꢇ (ꢉ$('ꢆꢘꢞꢛ ꢏ ꢋ99*ꢐ"
(ꢘ (% %ꢊꢘ ꢝꢈꢊꢉ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢘꢛꢆꢉ%+ꢊꢛꢛꢊ$ +ꢛꢞꢙ ꢘꢈꢊ ꢍꢃꢍ ꢘꢞ
ꢍ8ꢍ* ꢆꢉ$ ꢘꢈꢊ ꢘꢛꢆꢉ%+ꢊꢛ 'ꢆꢅ%ꢊ% ꢍ8ꢍ* ꢘꢞ ꢚꢊ'ꢞꢙꢊ +ꢅꢇꢇꢒ ꢎꢈ(%
ꢚ(ꢘ (% 'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ ꢀ,ꢋ ꢛꢊꢆ$% ꢍ8ꢍ*L ꢆꢉ$ ꢘꢈꢊꢛꢊꢚ&
Cꢗꢞꢗꢗ(ꢉ-D ꢘꢈꢊ # ꢂ" ꢙꢆ3(ꢉ- ꢛꢞꢞꢙ +ꢞꢛ ꢘꢈꢊ ꢉꢊ!ꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ #+
ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢝꢆ(ꢘ(ꢉ- (ꢉ ꢘꢈꢊ ꢍꢃꢍ ꢚꢊ'ꢆꢅ%ꢊ ꢍ8ꢍ* (% +ꢅꢇꢇ"
ꢘꢈ(% ꢚ(ꢘ ꢝ(ꢇꢇ ꢚꢊ %ꢊꢘ ꢆ-ꢆ(ꢉ ꢆ+ꢘꢊꢛ ꢘꢈꢊ ꢛꢊꢆ$ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ" ꢝꢈꢊꢉ ꢘꢈꢆꢘ
'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢇꢞꢆ$ꢊ$ (ꢉꢘꢞ ꢍ8ꢍ*ꢒ
ISR[1] RXRDYA/FFULL A - Channel A Receiver
Ready or FIFO Full
ꢎꢈꢊ +ꢅꢉ'ꢘ(ꢞꢉ ꢞ+ ꢘꢈ(% ꢚ(ꢘ (% %ꢊꢇꢊ'ꢘꢊ$ ꢚ& ꢗꢛꢞ-ꢛꢆꢙꢙ(ꢉ-
ꢁꢍꢔꢌN/Oꢒ #+ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢆ% ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢍꢊꢆ$&
(ꢉ$('ꢆꢘꢞꢛ ꢏꢍ5ꢍꢄGꢌꢐ" ꢘꢈ(% ꢚ(ꢘ (ꢉ$('ꢆꢘꢊ% ꢘꢈꢆꢘ ꢘꢈꢊꢛꢊ (% ꢆꢘ ꢇꢊꢆ%ꢘ
ꢞꢉꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢞ+ $ꢆꢘꢆ (ꢉ ꢍ8ꢍꢌ" ꢆꢉ$ (% ꢛꢊꢆ$& ꢘꢞ ꢚꢊ ꢛꢊꢆ$ ꢚ&
ꢘꢈꢊ ꢀ,ꢋꢒ ꢎꢈ(% ꢚ(ꢘ (% %ꢊꢘ ꢝꢈꢊꢉ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢘꢛꢆꢉ%+ꢊꢛꢛꢊ$
+ꢛꢞꢙ ꢘꢈꢊ ꢍꢃꢍ ꢘꢞ ꢍ8ꢍꢌ ꢆꢉ$ (% 'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ ꢀ,ꢋ
ꢛꢊꢆ$% ꢏꢞꢛ Cꢗꢞꢗ%Dꢐ ꢍ8ꢍꢌꢒ #+ ꢘꢈꢊꢛꢊ ꢆꢛꢊ %ꢘ(ꢇꢇ ꢙꢞꢛꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ%
(ꢉ ꢍ8ꢍꢌ" +ꢞꢇꢇꢞꢝ(ꢉ- ꢘꢈꢊ ꢛꢊꢆ$ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ" ꢘꢈꢊ ꢚ(ꢘ ꢝ(ꢇꢇ ꢚꢊ %ꢊꢘ
ꢆ-ꢆ(ꢉ ꢆ+ꢘꢊꢛ ꢍ8ꢍꢌ (% Cꢗꢞꢗꢗꢊ$Dꢒ
Note:
If this bit is configured to reflect the FFULLB indicator, this
bit will not be set (nor will produce an interrupt request) if
one or two characters are still remainingin RHRB, following
data reception. Hence, it is possible that the last two char-
acters in a string of data (being received) could be lost due
to this phenomenon.
#+ ꢘꢈ(% ꢚ(ꢘ (% ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢆ% ꢘꢈꢊ # ꢂ ꢏꢍ8ꢍꢐ +ꢅꢇꢇ (ꢉ$('ꢆꢘꢞꢛ
ꢏ ꢋ99ꢌꢐ" (ꢘ (% %ꢊꢘ ꢝꢈꢊꢉ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢘꢛꢆꢉ%+ꢊꢛꢛꢊ$ +ꢛꢞꢙ
ꢘꢈꢊ ꢍꢃꢍ ꢘꢞ ꢍ8ꢍꢌ ꢆꢉ$ ꢘꢈꢊ ꢉꢊꢝꢇ& ꢘꢛꢆꢉ%+ꢊꢛꢛꢊ$ 'ꢈꢆꢛꢆ'ꢘꢊꢛ
'ꢆꢅ%ꢊ% ꢍ8ꢍꢌ ꢘꢞ ꢚꢊ'ꢞꢙꢊ +ꢅꢇꢇꢒ ꢎꢈ(% ꢚ(ꢘ (% 'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ
ꢀ,ꢋ ꢛꢊꢆ$% ꢍ8ꢍꢌꢒ #+ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢝꢆ(ꢘ(ꢉ- (ꢉ ꢘꢈꢊ ꢍꢃꢍ
ꢚꢊ'ꢆꢅ%ꢊ ꢍ8ꢍꢌ (% +ꢅꢇꢇ" ꢘꢈ(% ꢚ(ꢘ ꢝ(ꢇꢇ ꢚꢊ %ꢊꢘ ꢆ-ꢆ(ꢉ" +ꢞꢇꢇꢞꢝ(ꢉ-
ꢘꢈꢊ ꢛꢊꢆ$ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ" ꢝꢈꢊꢉ ꢘꢈꢆꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢇꢞꢆ$ꢊ$ (ꢉꢘꢞ
ꢍ8ꢍꢌꢒ
ISR[4] TXRDYB - Channel B Transmitter Ready
ꢎꢈ(% ꢚ(ꢘ (% ꢆ $ꢅꢗꢇ('ꢆꢘꢊ ꢞ+ ꢎ5ꢍꢄG *" ꢃꢍ*NꢓOꢒ
ꢎꢈ(% ꢚ(ꢘ" ꢝꢈꢊꢉ %ꢊꢘ" (ꢉ$('ꢆꢘꢊ% ꢘꢈꢆꢘ ꢎ8ꢍ* (% ꢊꢙꢗꢘ& ꢆꢉ$ (%
ꢛꢊꢆ$& ꢘꢞ ꢆ''ꢊꢗꢘ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ +ꢛꢞꢙ ꢘꢈꢊ ꢀ,ꢋꢒ ꢎꢈꢊ ꢚ(ꢘ (%
'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ ꢀ,ꢋ ꢝꢛ(ꢘꢊ% ꢆ ꢉꢊꢝ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢘꢞ ꢎ8ꢍ*L
ꢆꢉ$ (% %ꢊꢘ ꢆ-ꢆ(ꢉ" ꢝꢈꢊꢉ ꢘꢈꢆꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢘꢛꢆꢉ%+ꢊꢛꢛꢊ$ ꢘꢞ ꢘꢈꢊ
ꢎꢃꢍꢒ ꢎ5ꢍꢄG* (% %ꢊꢘ ꢝꢈꢊꢉ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% (ꢉ(ꢘ(ꢆꢇꢇ&
ꢊꢉꢆꢚꢇꢊ$ ꢆꢉ$ (% 'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% $(%ꢆꢚꢇꢊ$ꢒ
Note:
If this bit is configured to reflect the FFULLA indicator, this
bit will not be set (nor will produce an interrupt request) if
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢔꢖ
XR88C681
one or two characters are still remainingin RHRA, following
data reception. Hence, it is possible that the last two char-
acters in a string of data (being received) could be lost due
to this phenomenon. Therefore, the user is advised to read
RHRA until empty.
ꢀꢈꢆꢛꢆ'ꢘꢊꢛ% ꢇꢞꢆ$ꢊ$ (ꢉꢘꢞ ꢎ8ꢍꢌ ꢝꢈ(ꢇꢊ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (%
$(%ꢆꢚꢇꢊ$ ꢝ(ꢇꢇ ꢉꢞꢘ ꢚꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ꢒ
C.2 Interrupt Mask Register (IMR)
ꢎꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢆ%3 ꢍꢊ-(%ꢘꢊꢛ (% ꢆ CBꢛ(ꢘꢊ ꢂꢉꢇ&D ꢛꢊ-(%ꢘꢊꢛ
ꢝꢈ('ꢈ ꢊꢉꢆꢚꢇꢊ% ꢘꢈꢊ ꢅ%ꢊꢛ ꢘꢞ %ꢊꢇꢊ'ꢘ ꢘꢈꢊ 'ꢞꢉ$(ꢘ(ꢞꢉ% ꢘꢈꢆꢘ ꢝ(ꢇꢇ
'ꢆꢅ%ꢊ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢘꢞ (%%ꢅꢊ ꢆꢉ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢍꢊEꢅꢊ%ꢘ ꢘꢞ ꢘꢈꢊ
ꢗꢛꢞ'ꢊ%%ꢞꢛꢒ #ꢉ ꢞꢘꢈꢊꢛ ꢝꢞꢛ$%" ꢘꢈꢊ ꢅ%ꢊꢛ ꢈꢆ% ꢘꢈꢊ ꢞꢗꢘ(ꢞꢉ ꢞ+
ꢙꢆ%3(ꢉ- ꢞꢛ ꢚꢇꢞ'3(ꢉ- 'ꢊꢛꢘꢆ(ꢉ 'ꢞꢉ$(ꢘ(ꢞꢉ% +ꢛꢞꢙ 'ꢆꢅ%(ꢉ- ꢘꢈꢊ
ꢄꢋꢌꢍꢎ ꢘꢞ (%%ꢅꢊ ꢆꢉ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢍꢊEꢅꢊ%ꢘꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢘꢈꢊ
ꢚ(ꢘꢜ+ꢞꢛꢙꢆꢘ ꢞ+ ꢘꢈꢊ #ꢁꢍ (% ꢊ%%ꢊꢉꢘ(ꢆꢇꢇ& ꢘꢈꢊ %ꢆꢙꢊ ꢆ% ꢘꢈꢊ #ꢃꢍꢒ
8ꢞꢝꢊꢑꢊꢛ" +ꢞꢛ 'ꢞꢙꢗꢇꢊꢘꢊꢉꢊ%%" ꢘꢈꢊ *(ꢘ ꢞꢛꢙꢆꢘ ꢞ+ ꢘꢈꢊ #ꢁꢍ (%
ꢗꢛꢊ%ꢊꢉꢘꢊ$ ꢈꢊꢛꢊꢒ
ISR[0]: Channel A Transmitter Ready
ꢎꢈ(% ꢚ(ꢘ (% ꢆ $ꢅꢗꢇ('ꢆꢘꢊ ꢞ+ ꢎ5ꢍꢄG ꢌ" ꢃꢍꢌNꢓOꢒ
ꢎꢈ(% ꢚ(ꢘ" ꢝꢈꢊꢉ %ꢊꢘ" (ꢉ$('ꢆꢘꢊ% ꢘꢈꢆꢘ ꢎ8ꢍꢌ (% ꢊꢙꢗꢘ& ꢆꢉ$ (%
ꢛꢊꢆ$& ꢘꢞ ꢆ''ꢊꢗꢘ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ +ꢛꢞꢙ ꢘꢈꢊ ꢀ,ꢋꢒ ꢎꢈꢊ ꢚ(ꢘ (%
'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ ꢀ,ꢋ ꢝꢛ(ꢘꢊ% ꢆ ꢉꢊꢝ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢘꢞ ꢎ8ꢍꢌL
ꢆꢉ$ (% %ꢊꢘ ꢆ-ꢆ(ꢉ" ꢝꢈꢊꢉ ꢘꢈꢆꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢘꢛꢆꢉ%+ꢊꢛꢛꢊ$ ꢘꢞ ꢘꢈꢊ
ꢎꢃꢍꢒ ꢎ5ꢍꢄGꢌ (% %ꢊꢘ ꢝꢈꢊꢉ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% (ꢉ(ꢘ(ꢆꢇꢇ&
ꢊꢉꢆꢚꢇꢊ$ ꢆꢉ$ (% 'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% $(%ꢆꢚꢇꢊ$ꢒ
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Input Port
Change
Delta Break
B
RXRDY/
FFULLB
TXRDYB
Counter
Ready
Delta Break
A
RXRDY/
FFULLA
TXRDYA
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
Table 6. IMR Bit Format
#+ ꢘꢈꢊ ꢅ%ꢊꢛ ꢝ(%ꢈꢊ% ꢘꢞ ꢊꢉꢆꢚꢇꢊ ꢆ 'ꢊꢛꢘꢆ(ꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ" ꢈꢊ.%ꢈꢊ
%ꢈꢞꢅꢇ$ ꢝꢛ(ꢘꢊ ꢆ CꢔD ꢘꢞ ꢘꢈꢊ ꢚ(ꢘ ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ #ꢁꢍ" 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ-
ꢘꢞ ꢘꢈꢆꢘ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢀꢞꢉ$(ꢘ(ꢞꢉꢒ 9(3ꢊꢝ(%ꢊ" ꢘꢞ $(%ꢆꢚꢇꢊ ꢞꢛ ꢙꢆ%3
ꢞꢅꢘ ꢆ 'ꢊꢛꢘꢆ(ꢉ 'ꢞꢉ$(ꢘ(ꢞꢉ 'ꢆꢅ%(ꢉ- ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ" ꢘꢈꢊ ꢅ%ꢊꢛ
%ꢈꢞꢅꢇ$ ꢝꢛ(ꢘꢊ ꢆ CꢕD ꢘꢞ ꢘꢈꢊ ꢚ(ꢘ ꢇꢞ'ꢆꢘ(ꢞꢉ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- ꢘꢞ ꢘꢈꢆꢘ
'ꢞꢉ$(ꢘ(ꢞꢉꢒ ꢎꢞ ꢊꢉꢆꢚꢇꢊ ꢆꢇꢇ (ꢉꢘꢊꢛꢛꢅꢗꢘ% ꢘꢈꢊ ꢅ%ꢊꢛ ꢝꢞꢅꢇ$ ꢝꢛ(ꢘꢊ
ꢙꢊꢙꢞꢛ&" +ꢞꢛ ꢇꢆꢘꢊꢛ ꢛꢊ'ꢆꢇꢇꢒ ꢎꢈꢊ ꢆ$$(ꢘ(ꢞꢉꢆꢇ ꢈꢆꢛ$ꢝꢆꢛꢊ ꢆꢉ$
%ꢞ+ꢘꢝꢆꢛꢊ ꢞꢑꢊꢛꢈꢊꢆ$ ꢛꢊEꢅ(ꢛꢊ$ ꢘꢞ %ꢅꢗꢗꢞꢛꢘ ꢘꢈ(% ꢆ'ꢘ(ꢑ(ꢘ& 'ꢆꢉ ꢚꢊ
ꢊꢇ(ꢙ(ꢉꢆꢘꢊ$ ꢑ(ꢆ ꢅ%ꢊ ꢞ+ ꢘꢈꢊ ꢁ#ꢃꢍꢒ
C.4 Interrupt Vector Register, IVR
ꢎꢈ(% ꢛꢊ-(%ꢘꢊꢛ (% ꢞꢉꢇ& ꢅ%ꢊ$ +ꢞꢛ #ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ -ꢊꢉꢊꢛꢆꢘ(ꢞꢉ
ꢝꢈꢊꢉ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% 'ꢞꢙꢙꢆꢉ$ꢊ$ (ꢉꢘꢞ ꢘꢈꢊ %ꢗꢊ'(ꢆꢇ ?ꢜꢁꢞ$ꢊꢒ
Bꢈ(ꢇꢊ (ꢉ ꢘꢈ(% ꢙꢞ$ꢊ" ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ #;ꢍ (% ꢘ&ꢗ('ꢆꢇꢇ&
ꢛꢊꢇꢆꢘꢊ$ ꢘꢞ ꢘꢈꢊ %ꢘꢆꢛꢘ(ꢉ- ꢆ$$ꢛꢊ%% ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ% #ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢃꢊꢛꢑ('ꢊ ꢍꢞꢅꢘ(ꢉꢊꢒ ꢂꢘꢈꢊꢛꢝ(%ꢊ" (ꢉ ꢘꢈꢊ #ꢜꢁꢞ$ꢊ" #ꢉꢘꢊꢛꢛꢅꢗꢘ
;ꢊ'ꢘꢞꢛ -ꢊꢉꢊꢛꢆꢘ(ꢞꢉ (% ꢘ&ꢗ('ꢆꢇꢇ& ꢗꢊꢛ+ꢞꢛꢙꢊ$ ꢞ++ꢜ'ꢈ(ꢗꢒ Bꢈꢊꢉ
ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ #ꢜꢁꢞ$ꢊ" ꢘꢈꢊ #;ꢍ 'ꢆꢉ ꢚꢊ
ꢅ%ꢊ$ ꢆ% -ꢊꢉꢊꢛꢆꢇ ꢗꢅꢛꢗꢞ%ꢊ ꢛꢊꢆ$.ꢝꢛ(ꢘꢊ ꢛꢊ-(%ꢘꢊꢛ%ꢒ ꢎꢈꢊ ꢛꢞꢇꢊ ꢞ+
ꢘꢈꢊ #;ꢍ" ꢝꢈ(ꢇꢊ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊ (%
ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ Section C.6ꢒ
ꢏꢆꢇꢇ CꢔD%ꢐ ꢘꢞ ꢘꢈ(% ꢛꢊ-(%ꢘꢊꢛ%ꢒ
ꢔ/
Please note that IMR is a Write Only Registers, and can
therefore not be read by the processor.
C.3 Masked Interrupt Status Register (MISR)
ꢎꢈꢊ 'ꢞꢉꢘꢊꢉꢘ ꢞ+ ꢘꢈꢊ ꢁ#ꢃꢍ ꢛꢊ-(%ꢘꢊꢛ (% ꢚꢆ%('ꢆꢇꢇ& ꢘꢈꢊ ꢛꢊ%ꢅꢇꢘ% ꢞ+
ꢌ7ꢄ(ꢉ- ꢘꢈꢊ #ꢃꢍ ꢆꢉ$ #ꢁꢍ ꢘꢞ-ꢊꢘꢈꢊꢛꢒ
ꢁ#ꢃꢍ ꢀꢞꢉꢘꢊꢉꢘ J N#ꢃꢍ ꢀꢞꢉꢘꢊꢉꢘ%O ꢁ N#ꢁꢍ ꢀꢞꢉꢘꢊꢉꢘ%O
ꢂꢉꢊ ꢇ(ꢙ(ꢘꢆꢘ(ꢞꢉ ꢞ+ ꢄꢋꢌꢍꢎ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢊꢛꢑ('ꢊ ꢍꢞꢅꢘ(ꢉꢊ% ꢘꢈꢆꢘ
ꢛꢊꢇ& ꢞꢉ ꢛꢊꢆ$(ꢉ- ꢘꢈꢊ #ꢃꢍ (% ꢘꢈꢆꢘ ꢘꢈꢊ ꢚ(ꢘ% ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ #ꢃꢍ 'ꢆꢉ
ꢘꢞ--ꢇꢊ Cꢈ(-ꢈD $ꢅꢊ ꢘꢞ ꢘꢈꢊ(ꢛ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- 'ꢞꢉ$(ꢘ(ꢞꢉ%
ꢝꢈꢊꢘꢈꢊꢛ ꢞꢛ ꢉꢞꢘ ꢘꢈꢊ& ꢆꢛꢊ ꢊꢉꢆꢚꢇꢊ$ ꢚ& ꢘꢈꢊ #ꢁꢍꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ"
ꢘꢈꢊ ꢅ%ꢊꢛ" +ꢞꢇꢇꢞꢝ(ꢉ- ꢛꢊꢆ$(ꢉ- ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ"
ꢝ(ꢇꢇ ꢈꢆꢑꢊ ꢘꢞ ꢙꢆ3ꢊ ꢗꢛꢞꢑ(%(ꢞꢉ% +ꢞꢛL ꢆꢉ$ ꢊ!ꢊ'ꢅꢘꢊ ꢆ Cꢚ(ꢘꢜꢚ&ꢜꢚ(ꢘD
ꢌ7ꢄ ꢞ+ ꢘꢈꢊ #ꢃꢍ ꢆꢉ$ #ꢁꢍ 'ꢞꢉꢘꢊꢉꢘ%ꢒ ꢃ(ꢉ'ꢊ ꢘꢈꢊ #ꢁꢍ (% ꢆ
CBꢛ(ꢘꢊ ꢂꢉꢇ&D ꢛꢊ-(%ꢘꢊꢛ ꢆꢉ$ 'ꢆꢉꢉꢞꢘ ꢚꢊ ꢛꢊꢆ$ ꢚ& ꢘꢈꢊ ꢗꢛꢞ'ꢊ%%ꢞꢛ"
ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ #ꢁꢍ ꢝ(ꢇꢇ ꢈꢆꢑꢊ ꢘꢞ ꢚꢊ %ꢘꢞꢛꢊ$ (ꢉ %&%ꢘꢊꢙ
C.5 Limitations of the DUART Interrupt Structure
ꢎꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢘꢛꢅ'ꢘꢅꢛꢊ ꢞ++ꢊꢛꢊ$ ꢚ& ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢆꢇꢇꢞꢝ% ꢘꢈꢊ
ꢅ%ꢊꢛ ꢘꢞ ꢗꢛꢞ-ꢛꢆꢙ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢘꢞ -ꢊꢉꢊꢛꢆꢘꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ% (ꢉ
ꢛꢊ%ꢗꢞꢉ%ꢊ ꢘꢞ 'ꢊꢛꢘꢆ(ꢉ ꢎ8ꢍ ꢆꢉ$ ꢍ8ꢍ ꢏ # ꢂꢐ 'ꢞꢉ$(ꢘ(ꢞꢉ%L ꢘꢈꢊ
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢍꢊꢆ$& 'ꢞꢉ$(ꢘ(ꢞꢉ" ꢆꢉ$ ꢘꢞ 'ꢈꢆꢉ-ꢊ% (ꢉ ꢘꢈꢊ
*ꢛꢊꢆ3 ꢀꢞꢉ$(ꢘ(ꢞꢉ ꢏꢆꢘ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛꢐꢒ 8ꢞꢝꢊꢑꢊꢛ" ꢆ%($ꢊ +ꢛꢞꢙ
ꢘꢈꢊ Cꢄꢊꢇꢘꢆ *ꢛꢊꢆ3 ꢀꢞꢉ$(ꢘ(ꢞꢉD ꢏꢍ*ꢐ" ꢘꢈꢊ ꢄꢋꢌꢍꢎH% #ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢃꢘꢛꢅ'ꢘꢅꢛꢊ $ꢞꢊ% ꢉꢞꢘ ꢆꢇꢇꢞꢝ +ꢞꢛ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ% $ꢅꢊ ꢘꢞ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢓꢕ
XR88C681
ꢍꢊ'ꢊ(ꢑꢊꢛ ꢗꢛꢞꢚꢇꢊꢙ% %ꢅ'ꢈ ꢆ% ,ꢆꢛ(ꢘ& 2ꢛꢛꢞꢛ ꢏ,2ꢐ" ꢍꢊ'ꢊ(ꢑꢊꢛ
ꢂꢑꢊꢛꢛꢅꢉ 2ꢛꢛꢞꢛ ꢏꢂ2ꢐ" ꢞꢛ ꢛꢆꢙ(ꢉ- 2ꢛꢛꢞꢛ ꢏ 2ꢐꢒ ꢎꢈꢊ ꢄꢋꢌꢍꢎ
ꢆꢇ%ꢞ $ꢞꢊ% ꢉꢞꢘ ꢞ++ꢊꢛ ꢘꢈꢊ ꢅ%ꢊꢛ ꢘꢞ ꢆꢚ(ꢇ(ꢘ& ꢘꢞ 'ꢞꢉ+(-ꢅꢛꢊ ꢞꢉꢊ ꢞ+
ꢘꢈꢊ ꢞꢅꢘꢗꢅꢘ ꢗꢞꢛꢘ% ꢘꢞ ꢛꢊꢇꢆ& ꢘꢈꢊ ꢞ''ꢅꢛꢛꢊꢉ'ꢊ ꢞ+ ꢆꢉ& ꢞ+ ꢘꢈꢊ%ꢊ
'ꢞꢉ$(ꢘ(ꢞꢉ%ꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢅꢉꢇꢊ%% ꢘꢈꢊ ꢅ%ꢊꢛ (% (ꢙꢗꢇꢊꢙꢊꢉꢘ(ꢉ-
%ꢞꢙꢊ %ꢞꢛꢘ ꢞ+ Cꢄꢆꢘꢆ 9(ꢉ3 9ꢆ&ꢊꢛD ꢊꢛꢛꢞꢛ 'ꢈꢊ'3(ꢉ- %'ꢈꢊꢙꢊ
%ꢅ'ꢈ ꢆ% ꢀꢍꢀ" ꢘꢈꢊ ꢅ%ꢊꢛ (% ꢆ$ꢑ(%ꢊ$ ꢘꢞ Cꢑꢆꢇ($ꢆꢘꢊD ꢘꢈꢊ
ꢛꢊ'ꢊ(ꢑꢊ$ $ꢆꢘꢆ ꢚ& +ꢛꢊEꢅꢊꢉꢘꢇ& ꢛꢊꢆ$(ꢉ- ꢘꢈꢊ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛL
ꢆꢉ$ 'ꢈꢊ'3(ꢉ- +ꢞꢛ ꢆꢉ& ꢉꢞꢉꢜIꢊꢛꢞ ꢅꢗꢗꢊꢛꢜꢉ(ꢚꢚꢇꢊ ꢑꢆꢇꢅꢊ%ꢒ ꢎꢈ(%
(% ꢊ%ꢗꢊ'(ꢆꢇꢇ& ꢘꢈꢊ 'ꢆ%ꢊ (+ ꢘꢈꢊ ꢅ%ꢊꢛ ꢈꢆ% %ꢊꢘ ꢘꢈꢊ 2ꢛꢛꢞꢛ ꢁꢞ$ꢊ ꢘꢞ
Cꢀꢈꢆꢛꢆ'ꢘꢊꢛD ꢏꢁꢍꢔꢉN6O J ꢕꢐꢒ
ꢁ =ꢕ=ꢕ• ꢀ,
ꢁ =ꢕ=6• ,
ꢁ /=8ꢀꢔꢔ• ꢀ
ꢁ ?ꢜ=ꢕ• , ꢏ#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢞ$ꢊ% ꢕ ꢆꢉ$ ꢔꢐ
8ꢞꢝꢊꢑꢊꢛ" ꢘꢈꢊ ꢄꢋꢌꢍꢎ %ꢈꢞꢅꢇ$ ꢚꢊ ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊ
ꢝꢈꢊꢉ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- ꢙ('ꢛꢞꢗꢛꢞ'ꢊ%%ꢞꢛ%.
ꢙ('ꢛꢞ'ꢞꢉꢘꢛꢞꢇꢇꢊꢛ%ꢒ
ꢁ =ꢕ==• ,
ꢁ =ꢕ=/• ,
ꢁ =ꢕꢓ=/ ꢜ =ꢕ<=/• ,%
ꢁ ,ꢊꢉꢘ(ꢅꢙ• ,
ꢁ ?ꢜ=ꢕ• , ꢏ#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢞ$ꢊ% ꢓꢐ
C.6 Servicing DUART Interrupts
ꢎꢈꢊ ꢉꢊ!ꢘ +ꢊꢝ %ꢊ'ꢘ(ꢞꢉ% ꢝ(ꢇꢇ ꢗꢛꢞꢑ($ꢊ $ꢊꢘꢆ(ꢇꢊ$ $(%'ꢅ%%(ꢞꢉ% ꢞ+
ꢄꢋꢌꢍꢎ.ꢁ('ꢛꢞꢗꢛꢞ'ꢊ%%ꢞꢛ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢆꢉ$ (ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢗꢛꢞ'ꢊ%%(ꢉ- ꢞꢉ ꢊꢆ'ꢈ ꢞ+ ꢘꢈꢊ ꢆꢚꢞꢑꢊꢜꢙꢊꢉꢘ(ꢞꢉꢊ$
ꢙ('ꢛꢞꢗꢛꢞ'ꢊ%%ꢞꢛ%ꢒ ꢛꢞꢙ ꢘꢈ(% $(%'ꢅ%%(ꢞꢉ" ꢆ $ꢊꢘꢆ(ꢇꢊ$
$ꢊ%'ꢛ(ꢗꢘ(ꢞꢉ ꢞ+ #ꢜꢁꢞ$ꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛꢞ'ꢊ%%(ꢉ- ꢆꢉ$ ?ꢜꢁꢞ$ꢊ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛꢞ'ꢊ%%(ꢉ- ꢝ(ꢇꢇ ꢊꢙꢊꢛ-ꢊꢒ
#ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('(ꢉ- ꢝ(ꢘꢈ ꢘꢈꢊ 5ꢍ==ꢀ/=ꢔ ꢄꢋꢌꢍꢎ +ꢆꢇꢇ% (ꢉꢘꢞ
ꢘꢝꢞ ꢚꢛꢞꢆ$ 'ꢆꢘꢊ-ꢞꢛ(ꢊ%4 #ꢜꢁꢞ$ꢊ ꢆꢉ$ ?ꢜꢁꢞ$ꢊꢒ #ꢜꢁꢞ$ꢊ ꢈꢆ%
ꢈ(%ꢘꢞꢛ('ꢆꢇꢇ& ꢚꢊꢊꢉ ꢛꢊ+ꢊꢛꢛꢊ$ ꢘꢞ ꢆ% ꢘꢈꢊ C#ꢉꢘꢊꢇD ꢁꢞ$ꢊꢒ 9(3ꢊꢝ(%ꢊ"
ꢘꢈꢊ ?ꢜꢁꢞ$ꢊ ꢈꢆ% ꢚꢊꢊꢉ ꢛꢊ+ꢊꢛꢛꢊ$ ꢘꢞ ꢆ% ꢘꢈꢊ C?(ꢇꢞ-D ꢁꢞ$ꢊꢒ
Bꢈꢊꢉ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊ" ꢘꢈꢊ ꢄꢋꢌꢍꢎ
ꢝ(ꢇꢇ ꢗꢇꢆ'ꢊ ꢆꢉ = ꢚ(ꢘ C(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢑꢊ'ꢘꢞꢛD ꢞꢉ ꢘꢈꢊ $ꢆꢘꢆ ꢚꢅ%" ꢘꢞ ꢘꢈꢊ
ꢀ,ꢋ" $ꢅꢛ(ꢉ- ꢘꢈꢊ C#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊD ꢞꢛ #ꢌꢀ: '&'ꢇꢊꢒ
ꢎꢈꢊ ꢀ,ꢋ ꢝ(ꢇꢇ ꢛꢊꢆ$ ꢘꢈ(% (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢑꢊ'ꢘꢞꢛ +ꢛꢞꢙ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ%"
ꢆꢉ$ $ꢊꢘꢊꢛꢙ(ꢉꢊ ꢏ+ꢛꢞꢙ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ $ꢆꢘꢆꢐ ꢘꢈꢊ
ꢇꢞ'ꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ" (ꢉ
%&%ꢘꢊꢙ ꢙꢊꢙꢞꢛ&ꢒ ꢌ$$(ꢘ(ꢞꢉꢆꢇꢇ&" ꢘꢈꢊ ?ꢜꢁꢞ$ꢊ -(ꢑꢊ% ꢘꢈꢊ ꢅ%ꢊꢛ
ꢆ ꢈꢆꢛ$ꢝꢆꢛꢊ ꢆꢗꢗꢛꢞꢆ'ꢈ ꢘꢞ ꢗꢛ(ꢞꢛ(ꢘ(Iꢊ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ%
ꢆꢙꢞꢉ- ꢉꢅꢙꢊꢛꢞꢅ% ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ%ꢒ ꢎꢈ(% ꢗꢈꢊꢉꢞꢙꢊꢉꢞꢉ
(% $(%'ꢅ%%ꢊ$ (ꢉ -ꢛꢊꢆꢘꢊꢛ $ꢊꢘꢆ(ꢇ (ꢉ Section C.6.2ꢒ
C.6.1 I-Mode Interrupt Servicing
ꢎꢈꢊ ꢄꢋꢌꢍꢎ ꢝ(ꢇꢇ ꢚꢊ (ꢉ ꢘꢈꢊ #ꢜꢁꢞ$ꢊ +ꢞꢇꢇꢞꢝ(ꢉ- ꢗꢞꢝꢊꢛ ꢅꢗ ꢞ+ ꢘꢈꢊ
#ꢀ" ꢞꢛ ꢆ ꢈꢆꢛ$ꢝꢆꢛꢊ ꢛꢊ%ꢊꢘꢒ #ꢉ -ꢊꢉꢊꢛꢆꢇ" ꢆ ꢀ,ꢋ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢞ ꢆ
ꢄꢋꢌꢍꢎ ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ #ꢜꢁꢞ$ꢊ" ꢝ(ꢇꢇ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% +ꢞꢇꢇꢞꢝ%"
$ꢅꢛ(ꢉ- (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('(ꢉ-ꢒ
#+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢛꢊEꢅ(ꢛꢊ% (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ +ꢛꢞꢙ ꢘꢈꢊ ꢀ,ꢋ" (ꢘ
ꢝ(ꢇꢇ ꢆ%%ꢊꢛꢘ% ꢘꢈꢊ ꢜ#7ꢎꢍ ꢗ(ꢉ ꢘꢞ ꢘꢈꢊ ꢀ,ꢋꢒ ꢂꢉ'ꢊ ꢘꢈꢊ ꢀ,ꢋ ꢈꢆ%
$ꢊꢘꢊ'ꢘꢊ$ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ" (ꢘ ꢝ(ꢇꢇ $ꢊꢘꢊꢛꢙ(ꢉꢊ ꢘꢈꢊ
ꢇꢞ'ꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ" ꢆꢉ$
ꢝ(ꢇꢇ ꢚꢛꢆꢉ'ꢈ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢘꢞ ꢘꢈꢆꢘ ꢇꢞ'ꢆꢘ(ꢞꢉꢒ ꢎꢈꢊ ꢀ,ꢋ ꢝ(ꢇꢇ
ꢆ''ꢞꢙꢗꢇ(%ꢈ ꢆꢇꢇ ꢞ+ ꢘꢈ(% ꢝ(ꢘꢈꢞꢅꢘ ꢗꢛꢞꢑ($(ꢉ- ꢆꢉ C#ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊD %(-ꢉꢆꢇ ꢞꢛ ꢆꢉ& +ꢅꢛꢘꢈꢊꢛ (ꢉꢘꢊꢛꢆ'ꢘ(ꢞꢉ ꢝ(ꢘꢈ ꢘꢈꢊ
ꢄꢋꢌꢍꢎꢒ ꢂꢉ'ꢊ ꢘꢈꢊ ꢀ,ꢋ ꢈꢆ% ꢊꢇ(ꢙ(ꢉꢆꢘꢊ$ ꢘꢈꢊ 'ꢆꢅ%ꢊꢏ%ꢐ ꢞ+ ꢘꢈꢊ
ꢄꢋꢌꢍꢎH% (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ" ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢝ(ꢇꢇ ꢘꢈꢊꢉ ꢉꢊ-ꢆꢘꢊ
(ꢘ% ꢜ#7ꢎꢍ ꢗ(ꢉꢒ ꢎꢈꢊ ꢀ,ꢋ ꢝ(ꢇꢇ ꢘꢈꢊꢉ ꢊ!(ꢘ ꢘꢈꢊ CꢄꢋꢌꢍꢎD
(ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ ꢆꢉ$ ꢝ(ꢇꢇ ꢛꢊ%ꢅꢙꢊ ꢉꢞꢛꢙꢆꢇ
ꢗꢛꢞ'ꢊ%%(ꢉ-ꢒ
Bꢈꢊꢉ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ #ꢜꢁꢞ$ꢊ" ꢘꢈꢊ ꢄꢋꢌꢍꢎ
ꢝ(ꢇꢇ ꢉꢞꢘ ꢗꢛꢞꢑ($ꢊ ꢆꢉ& (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢑꢊ'ꢘꢞꢛ (ꢉ+ꢞꢛꢙꢆꢘ(ꢞꢉ ꢘꢞ ꢘꢈꢊ
ꢀ,ꢋ" $ꢅꢛ(ꢉ- ꢘꢈꢊ #ꢌꢀ: '&'ꢇꢊꢒ #ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ (ꢉ+ꢞꢛꢙꢆꢘ(ꢞꢉ"
ꢞꢛ ꢆꢉ& ꢙꢊꢆꢉ% ꢘꢞ ꢛꢞꢅꢘꢊ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢘꢞ ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢊꢛꢑ('ꢊ ꢍꢞꢅꢘ(ꢉꢊ" (% ꢆ''ꢞꢙꢗꢇ(%ꢈꢊ$ ꢊ!ꢘꢊꢛꢉꢆꢇ ꢘꢞ ꢘꢈꢊ
ꢄꢋꢌꢍꢎꢒ
ꢎꢈꢊ ꢄꢋꢌꢍꢎ ꢝ(ꢇꢇ ꢚꢊ (ꢉ ꢘꢈꢊ #ꢜꢁꢞ$ꢊ +ꢞꢇꢇꢞꢝ(ꢉ- ꢗꢞꢝꢊꢛ ꢅꢗ ꢞꢛ ꢆ
ꢈꢆꢛ$ꢝꢆꢛꢊ ꢛꢊ%ꢊꢘꢒ ꢎꢈꢊ ꢅ%ꢊꢛ ꢙꢅ%ꢘ (ꢉꢑꢞ3ꢊ ꢘꢈꢊ Cꢃꢊꢘ ?ꢜꢁꢞ$ꢊD
'ꢞꢙꢙꢆꢉ$" (ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ 'ꢞꢙꢙꢆꢉ$ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (ꢉꢘꢞ ꢘꢈꢊ
?ꢜꢁꢞ$ꢊꢒ
#ꢉ -ꢊꢉꢊꢛꢆꢇ ꢘꢈꢊꢛꢊ ꢆꢛꢊ ꢘꢝꢞ ꢆꢗꢗꢛꢞꢆ'ꢈꢊ% ꢘꢈꢆꢘ ꢀ,ꢋ%
'ꢞꢙꢙꢞꢉꢇ& ꢅ%ꢊ ꢘꢞ ꢇꢞ'ꢆꢘꢊ ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ
ꢛꢞꢅꢘ(ꢉꢊ" ꢝꢈꢊꢉ (ꢉꢘꢊꢛ+ꢆ'ꢊ$ ꢝ(ꢘꢈ ꢆꢉ #ꢜꢁꢞ$ꢊ ꢄꢋꢌꢍꢎꢒ
ꢌꢇꢘꢈꢞꢅ-ꢈ ꢘꢈꢊ #ꢜꢁꢞ$ꢊ ꢈꢆ% ꢚꢊꢊꢉ ꢛꢊ+ꢊꢛꢛꢊ$ ꢘꢞ ꢆ% ꢘꢈꢊ C#ꢉꢘꢊꢇD
ꢁꢞ$ꢊ" ꢆꢉ$ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊ ꢆ% ꢘꢈꢊ C?(ꢇꢞ-D ꢁꢞ$ꢊL ꢘꢈ(% $ꢞꢊ% ꢉꢞꢘ
ꢙꢊꢆꢉ ꢘꢈꢆꢘ ꢘꢈꢊ ꢅ%ꢊꢛ %ꢈꢞꢅꢇ$ ꢞꢉꢇ& ꢞꢗꢊꢛꢆꢘꢊ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (ꢉ ꢘꢈꢊ
?ꢜꢁꢞ$ꢊ ꢝꢈꢊꢉ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢆ ?(ꢇꢞ- ꢙ('ꢛꢞꢗꢛꢞ'ꢊ%%ꢞꢛ" ꢞꢛ (ꢉ ꢘꢈꢊ
#ꢜꢁꢞ$ꢊ ꢝꢈꢊꢉ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢞ ꢆꢉ #ꢉꢘꢊꢇ ꢙ('ꢛꢞꢗꢛꢞ'ꢊ%%ꢞꢛꢒ ꢎꢈꢊ
$(ꢑ(%(ꢞꢉ ꢚꢊꢘꢝꢊꢊꢉ #ꢜꢁꢞ$ꢊ ꢆꢉ$ ?ꢜꢁꢞ$ꢊ (% ꢉꢞꢘ ꢉꢊ'ꢊ%%ꢆꢛ&
ꢆꢇꢞꢉ- C'ꢞꢛꢗꢞꢛꢆꢘꢊD ꢇ(ꢉꢊ%ꢒ #+ &ꢞꢅ ꢆꢛꢊ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢈꢊ ꢄꢋꢌꢍꢎ
ꢘꢞ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- ꢙ('ꢛꢞꢗꢛꢞ'ꢊ%%ꢞꢛ%. ꢙ('ꢛꢞ'ꢞꢉꢘꢛꢞꢇꢇꢊꢛ%" ꢘꢈꢊꢉ
ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢙꢅ%ꢘ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈꢊ #ꢜꢁꢞ$ꢊꢒ
ꢁ ꢄ(ꢛꢊ'ꢘ #ꢉꢘꢊꢛꢛꢅꢗꢘ ,ꢛꢞ'ꢊ%%(ꢉ-
ꢁ ꢏ2!ꢘꢊꢛꢉꢆꢇꢐ ;ꢊ'ꢘꢞꢛꢊ$ꢜ#ꢉꢘꢊꢛꢛꢅꢗꢘ ,ꢛꢞ'ꢊ%%(ꢉ-
Direct Interrupt Processing
#+ ꢆ ꢀ,ꢋ ꢊꢙꢗꢇꢞ&% Cꢄ(ꢛꢊ'ꢘ #ꢉꢘꢊꢛꢛꢅꢗꢘ ,ꢛꢞ'ꢊ%%(ꢉ-D ꢘꢈꢊꢉ ꢞꢉ'ꢊ
ꢘꢈꢊ ꢀ,ꢋ ꢈꢆ% $ꢊꢘꢊ'ꢘꢊ$ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ" ꢆꢉ$ ꢈꢆ%
'ꢞꢙꢗꢇꢊꢘꢊ$ (ꢘ% 'ꢅꢛꢛꢊꢉꢘ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ" ꢘꢈꢊ ꢀ,ꢋ ꢝ(ꢇꢇ ꢚꢛꢆꢉ'ꢈ
ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢘꢞ ꢆ %ꢗꢊ'(+(' ꢇꢞ'ꢆꢘ(ꢞꢉ (ꢉ %&%ꢘꢊꢙ ꢙꢊꢙꢞꢛ&ꢒ
ꢁ =ꢕ6ꢔ• ,
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢓꢔ
XR88C681
ꢞꢛ ꢀ,ꢋ% ꢘꢈꢆꢘ ꢊꢙꢗꢇꢞ& $(ꢛꢊ'ꢘ (ꢉꢘꢊꢛꢛꢅꢗꢘ%" ꢘꢈ(% Cꢇꢞ'ꢆꢘ(ꢞꢉD (%
+(!ꢊ$ ꢚ& ꢘꢈꢊ ꢀ,ꢋ '(ꢛ'ꢅ(ꢘꢛ& (ꢘ%ꢊꢇ+ꢒ
ꢚꢊ'ꢆꢅ%ꢊ ꢘꢈꢊ ꢇꢞ'ꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ (%
$ꢊꢘꢊꢛꢙ(ꢉꢊ$ ꢚ& ꢈꢆꢛ$ꢝꢆꢛꢊ Cꢊ!ꢘꢊꢛꢉꢆꢇD ꢘꢞ ꢘꢈꢊ ꢄꢋꢌꢍꢎꢒ ꢞꢛ
%ꢞꢙꢊ ꢀ,ꢋ%" ꢏ%ꢅ'ꢈ ꢆ% ꢘꢈꢊ =ꢕ=ꢕꢌ ꢆꢉ$ ꢘꢈꢊ =ꢕ=6• ,ꢐ" ꢘꢈ(%
C(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢑꢊ'ꢘꢞꢛD (ꢉ+ꢞꢛꢙꢆꢘ(ꢞꢉ (% ꢆ ꢞꢉꢊ ꢚ&ꢘꢊ ꢞꢗꢜ'ꢞ$ꢊ +ꢞꢛ ꢆ
ꢀꢌ99 (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ ꢘꢞ ꢆ %ꢗꢊ'(ꢆꢇ Cꢍ2ꢃꢎꢌꢍꢎ %ꢅꢚꢛꢞꢅꢘ(ꢉꢊDꢒ
ꢎꢈꢊ ꢇꢞ'ꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈ(% Cꢍ2ꢃꢎꢌꢍꢎ %ꢅꢚꢛꢞꢅꢘ(ꢉꢊD (% +(!ꢊ$ ꢚ&
ꢀ,ꢋ '(ꢛ'ꢅ(ꢘ $ꢊ%(-ꢉꢒ #+ ꢘꢈꢊ ꢅ%ꢊꢛ ꢊꢙꢗꢇꢞ&% ꢘꢈ(% ꢆꢗꢗꢛꢞꢆ'ꢈ +ꢞꢛ
(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛꢞ'ꢊ%%(ꢉ-" ꢈꢊ.%ꢈꢊ (% ꢛꢊ%ꢗꢞꢉ%(ꢚꢇꢊ +ꢞꢛ (ꢉ%ꢅꢛ(ꢉ-
ꢘꢈꢆꢘ ꢊ(ꢘꢈꢊꢛ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ" ꢞꢛ ꢆꢉ
ꢅꢉ'ꢞꢉ$(ꢘ(ꢞꢉꢆꢇ ꢚꢛꢆꢉ'ꢈ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ ꢏꢘꢞ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ
ꢛꢞꢅꢘ(ꢉꢊꢐ ꢛꢊ%($ꢊ% ꢆꢘ ꢘꢈ(% ꢇꢞ'ꢆꢘ(ꢞꢉ (ꢉ ꢙꢊꢙꢞꢛ&ꢒ
ꢞꢛ 2!ꢆꢙꢗꢇꢊ4
#+ ꢘꢈꢊ ꢜ#7ꢎꢕ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘ ꢗ(ꢉ" ꢞ+ ꢘꢈꢊ =ꢕ6ꢔ• ꢀ" (%
ꢆ%%ꢊꢛꢘꢊ$" ꢘꢈꢊ ꢀ,ꢋ ꢝ(ꢇꢇ ꢚꢛꢆꢉ'ꢈ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢘꢞ ꢇꢞ'ꢆꢘ(ꢞꢉ
ꢕꢕꢕ1 (ꢉ %&%ꢘꢊꢙ ꢙꢊꢙꢞꢛ&ꢒ ꢎꢈ(% ꢇꢞ'ꢆꢘ(ꢞꢉ (% +(!ꢊ$ ꢏꢚ& '(ꢛ'ꢅ(ꢘ
ꢔ/
$ꢊ%(-ꢉ ꢞ+ ꢘꢈꢊ =ꢕ6ꢔ• ,ꢐ ꢆꢉ$ 'ꢆꢉꢉꢞꢘ ꢚꢊ 'ꢈꢆꢉ-ꢊ$ ꢚ& ꢘꢈꢊ
ꢅ%ꢊꢛꢒ
(External) Vectored Interrupt Processing
2ꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ,ꢛꢞ'ꢊ%%(ꢉ- ꢘꢊ'ꢈꢉ(Eꢅꢊ% ꢝ(ꢇꢇ ꢚꢊ
ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ -ꢛꢊꢆꢘꢊꢛ $ꢊꢘꢆ(ꢇ (ꢉ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- %ꢊ'ꢘ(ꢞꢉ%ꢒ
ꢀ,ꢋ% ꢘꢈꢆꢘ ꢊꢙꢗꢇꢞ& ꢘꢈ(% +ꢞꢛꢙ ꢞ+ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛꢞ'ꢊ%%(ꢉ-
ꢘ&ꢗ('ꢆꢇꢇ& ꢈꢆꢑꢊ ꢆꢉ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊ ꢞꢅꢘꢗꢅꢘ ꢗ(ꢉꢒ ꢎꢈ(%
C#ꢌꢀ:D ꢞꢛ Cꢜ#7ꢎꢌD ꢞꢅꢘꢗꢅꢘ ꢝ(ꢇꢇ ꢚꢊ ꢅ%ꢊ$ ꢘꢞ -ꢆꢘꢊ C(ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢑꢊ'ꢘꢞꢛD (ꢉ+ꢞꢛꢙꢆꢘ(ꢞꢉ ꢞꢉꢘꢞ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ%" ꢑ(ꢆ ꢊ!ꢘꢊꢛꢉꢆꢇ
ꢏꢉꢞꢉꢜꢄꢋꢌꢍꢎꢐ ꢈꢆꢛ$ꢝꢆꢛꢊꢒ ꢎꢈꢊ ꢘꢊꢛꢙ C2!ꢘꢊꢛꢉꢆꢇD (% ꢅ%ꢊ$ ꢘꢞ
$ꢊ%'ꢛ(ꢚꢊ ꢘꢈ(% +ꢞꢛꢙ ꢞ+ ꢑꢊ'ꢘꢞꢛꢊ$ꢜ(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛꢞ'ꢊ%%(ꢉ-L
ꢌ% ꢙꢊꢉꢘ(ꢞꢉꢊ$ ꢊꢆꢛꢇ(ꢊꢛ" ꢘꢈꢊ ꢄꢋꢌꢍꢎ %ꢈꢞꢅꢇ$ ꢚꢊ ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ
ꢘꢈꢊ #ꢜꢁꢞ$ꢊ" ꢝꢈꢊꢉ (ꢉꢘꢊꢛ+ꢆ'ꢊ$ ꢘꢞ ꢘꢈꢊ • ,.• ꢀ ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ
Table 7ꢒ Table 7 ꢆꢇ%ꢞ ꢗꢛꢊ%ꢊꢉꢘ% ꢘꢈꢊ ꢘ&ꢗꢊ ꢞ+ (ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢗꢛꢞ'ꢊ%%(ꢉ- ꢘꢈꢆꢘ (% ꢊꢙꢗꢇꢞ&ꢊ$ ꢚ& ꢊꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ • ,%.• ꢀ%ꢒ
• P/• C
Type of Interrupt Processing
Comments
=ꢕ6ꢔ• ꢀ
ꢄ(ꢛꢊ'ꢘ
ꢎꢈꢊ =ꢕ6ꢔ • ꢀ ꢈꢆ% ꢘꢝꢞ ꢊ!ꢘꢊꢛꢉꢆꢇ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢍꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘ%4 ꢜ#7ꢎꢕ
ꢆꢉ$ ꢜ#7ꢎꢔꢒ
=ꢕ=ꢕꢌ• ,
2!ꢘꢊꢛꢉꢆꢇ ;ꢊ'ꢘꢞꢛꢊ$
ꢎꢈꢊ =ꢕ=ꢕꢌ • , ꢝ(ꢇꢇ ꢆꢇꢇꢞꢝ ꢘꢈꢊ ꢅ%ꢊ ꢞ+ ꢅꢗ ꢘꢞ = $(++ꢊꢛꢊꢉꢘ ꢞꢗ 'ꢞ$ꢊ%
+ꢞꢛ Cꢀꢌ99D (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ% ꢘꢞ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢊꢛꢑ('ꢊ ꢍꢞꢅꢘ(ꢉꢊ%ꢒ
ꢎꢈꢊ =ꢕ=ꢕꢌ ꢀ,ꢋ ꢙꢞ$ꢅꢇꢊ ꢝ(ꢇꢇ ꢞꢅꢘꢗꢅꢘ ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢆ'ꢜ
3ꢉꢞꢝꢇꢊ$-ꢊ ꢞꢅꢘꢗꢅꢘ" ꢜ#7ꢎꢌ" ꢝꢈ('ꢈ 'ꢆꢉ ꢚꢊ ꢅ%ꢊ$ ꢘꢞ C-ꢆꢘꢊD
ꢘꢈꢊ Cꢀꢌ99D (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ% ꢞꢉ ꢘꢞ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ%ꢒ
=ꢕ=6• ,
ꢄ(ꢛꢊ'ꢘ ꢆꢉ$ 2!ꢘꢊꢛꢉꢆꢇ ;ꢊ'ꢘꢞꢛꢊ$
ꢎꢈꢊ =ꢕ=6 • , ꢈꢆ% ꢘꢈꢛꢊꢊ Cꢄ(ꢛꢊ'ꢘD ꢊ!ꢘꢊꢛꢉꢆꢇ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢍꢊEꢅꢊ%ꢘ
(ꢉꢗꢅꢘ%4 ꢍꢃꢎ >ꢒ6" ꢍꢃꢎ /ꢒ6" ꢆꢉ$ ꢍꢃꢎ 6ꢒ6ꢒ ꢌ$$(ꢘ(ꢞꢉꢆꢇꢇ&" ꢘꢈ(% • ,
ꢈꢆ% ꢘꢈꢊ ꢊ!ꢆ'ꢘ %ꢆꢙꢊ Cꢑꢊ'ꢘꢞꢛD ꢞꢗꢘ(ꢞꢉ% ꢆ% $ꢞꢊ% ꢘꢈꢊ =ꢕ=ꢕꢌ • ,ꢒ
ꢄ(ꢛꢊ'ꢘ
ꢎꢈꢊ /=8ꢀꢔꢔ • ꢀ ꢈꢆ% ꢆ %(ꢉ-ꢇꢊ Cꢙꢆ%3ꢆꢚꢇꢊD ꢊ!ꢘꢊꢛꢉꢆꢇ #ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢍꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘL ꢜ#ꢍ)ꢒ
/=8ꢀꢔꢔ• ꢀ
?ꢜ=ꢕ• ,
ꢏ#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢞ$ꢊ ꢕꢐ
2!ꢘꢊꢛꢉꢆꢇ ;ꢊ'ꢘꢞꢛꢊ$
ꢄ(ꢛꢊ'ꢘ #ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢎꢈꢊ ?ꢜ=ꢕ ꢀ,ꢋ ꢅ%ꢊ% ꢘꢈꢊ ꢊ!ꢆ'ꢘ %ꢆꢙꢊ ꢆꢗꢗꢛꢞꢆ'ꢈ ꢆ% ꢗꢛꢊ%ꢊꢉꢘꢊ$
+ꢞꢛ ꢘꢈꢊ =ꢕ=ꢕꢌ ꢀ,ꢋꢒ
?ꢜ=ꢕ• ,
ꢎꢈꢊ ?ꢜ=ꢕ ꢝ(ꢇꢇ ꢚꢛꢆꢉ'ꢈ ꢘꢞ ꢕꢕ1=8 (ꢉ %&%ꢘꢊꢙ ꢙꢊꢙꢞꢛ& (+ ꢘꢈꢊ ꢜ#7ꢎ
(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ ꢗ(ꢉ (% ꢆ%%ꢊꢛꢘꢊ$ꢒ
Table 7. Summary of • P/• C and their types of Interrupt Processing (I - Mode)
ꢎꢈꢊ (ꢉ+ꢞꢛꢙꢆꢘ(ꢞꢉ ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ Table 7 (% $(%'ꢅ%%ꢊ$ (ꢉ $ꢊꢘꢆ(ꢇ (ꢉ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- %ꢊ'ꢘ(ꢞꢉ%ꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢓꢓ
XR88C681
C.6.1.1 8051 Microcontroller
ꢎꢈꢊ =ꢕ6ꢔ +ꢆꢙ(ꢇ& ꢞ+ ꢙ('ꢛꢞ'ꢞꢉꢘꢛꢞꢇꢇꢊꢛ% (% ꢙꢆꢉꢅ+ꢆ'ꢘꢅꢛꢊ$ ꢚ& #ꢉꢘꢊꢇ ꢆꢉ$ 'ꢞꢙꢊ% ꢝ(ꢘꢈ ꢆ ꢑꢆꢛ(ꢊꢘ& ꢞ+ ꢆꢙꢊꢉ(ꢘ(ꢊ%ꢒ ꢃꢞꢙꢊ ꢞ+ ꢘꢈꢊ%ꢊ
ꢆꢙꢊꢉ(ꢘ(ꢊ% (ꢉ'ꢇꢅ$ꢊ4
ꢁ ꢂꢉ 'ꢈ(ꢗ %ꢊꢛ(ꢆꢇ ꢗꢞꢛꢘ
ꢁ ꢞꢅꢛ = ꢚ(ꢘ #.ꢂ ꢗꢞꢛꢘ ꢏ,ꢕ ꢜ ,1ꢐ
ꢁ ꢎꢝꢞ ꢔ/ ꢚ(ꢘ ꢘ(ꢙꢊꢛ%
ꢁ <3 ꢚ&ꢘꢊ% ꢞ+ ꢍꢂꢁ
ꢁ ꢔꢓ= ꢚ&ꢘꢊ% ꢞ+ ꢍꢌꢁ
Figure 3 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ ꢚꢇꢞ'3 $(ꢆ-ꢛꢆꢙ ꢞ+ ꢘꢈꢊ =ꢕ6ꢔ ꢙ('ꢛꢞ'ꢞꢉꢘꢛꢞꢇꢇꢊꢛ" ꢆꢉ$ Figure 4 ꢗꢛꢊ%ꢊꢉꢘ% ꢘꢈꢊ ꢗ(ꢉ ꢞꢅꢘ ꢞ+ ꢘꢈ(% $ꢊꢑ('ꢊꢒ
ꢜ#7ꢎꢔ
ꢜ#7ꢎꢕ
ꢜꢎꢓ25
ꢎ(ꢙꢊꢛ ꢓ ꢏ=ꢕ1ꢓ.=ꢕ6ꢓꢐ
ꢎ(ꢙꢊꢛ ꢔ
ꢎ(ꢙꢊꢛ ꢕ
ꢎ(ꢙꢊꢛ ꢓ
ꢔꢓ= ꢚ&ꢘꢊ%
ꢍꢌꢁ
ꢏ=ꢕ1ꢓ.=ꢕ6ꢓꢐ
ꢜꢎꢓ
ꢜꢎꢔ
ꢏ=ꢕ1ꢓ.=ꢕ6ꢓꢐ
ꢃꢊꢛ(ꢆꢇ ,ꢞꢛꢘ
ꢍꢂꢁ
ꢎ(ꢙꢊꢛ ꢔ
ꢎ(ꢙꢊꢛ ꢕ
ꢕ: ꢜ =ꢕ1ꢔ.=ꢕ1ꢓ
<: ꢜ =ꢕ6ꢔ
=: ꢜ =ꢕ6ꢓ
#ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢀꢞꢉꢘꢛꢞꢇ
ꢔꢓ= ꢚ&ꢘꢊ%
ꢍꢌꢁ
ꢂꢘꢈꢊꢛ
ꢜꢎꢕ
ꢍꢊ-(%ꢘꢊꢛ%
ꢀ,ꢋ
ꢂ%'(ꢇꢇꢆꢘꢞꢛ
ꢃꢊꢛ(ꢆꢇ ,ꢞꢛꢘ
#.ꢂ ,ꢞꢛꢘ%
*ꢅ% ꢀꢞꢉꢘꢛꢞꢇ
ꢌ92
ꢜ2ꢌ
ꢍꢃꢎ
ꢜ,ꢃ27
,ꢕ
,ꢔ
,ꢓ
,1
ꢜꢍ5ꢄ
ꢜꢎ5ꢄ
Figure 3. Block Diagram of the 8051 Microcontroller
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢓ1
XR88C681
<ꢕ
,ꢔꢒꢕ
,ꢔꢒꢔ
,ꢔꢒꢓ
,ꢔꢒ1
,ꢔꢒ<
ꢔ
ꢓ
1
<
6
;
ꢀꢀ
,ꢕꢒꢕ ꢏꢌꢄꢕꢐ
1ꢖ
1=
1>
,ꢕꢒꢔ ꢏꢌꢄꢔꢐ
,ꢕꢒꢓ ꢏꢌꢄꢓꢐ
1/ ,ꢕꢒ1 ꢏꢌꢄ1ꢐ
16
,ꢔꢒ6
,ꢔꢒ/
/
>
,ꢕꢒ< ꢏꢌꢄ<ꢐ
,ꢕꢒ6 ꢏꢌꢄ6ꢐ
1<
11
1ꢓ
8051
Microcontroller
,ꢔꢒ>
ꢍꢃꢎ
=
ꢖ
,ꢕꢒ/ ꢏꢌꢄ/ꢐ
,ꢕꢒ> ꢏꢌꢄ>ꢐ
1ꢔ ꢜ2ꢌ
,1ꢒꢕ ꢏꢍ5ꢄꢐ ꢔꢕ
,1ꢒꢔ ꢏꢎ5ꢄꢐ
ꢌ92
ꢔꢔ
,1ꢒꢓ ꢏꢜ#7ꢎꢕꢐ ꢔꢓ
1ꢕ
ꢓꢖ
ꢜ,ꢃ27
ꢔ1
ꢔ<
ꢔ6
ꢔ/
ꢔ>
,1ꢒ1 ꢏꢜ#7ꢎꢔꢐ
,1ꢒ< ꢏꢎꢕꢐ
ꢓ= ,ꢓꢒ> ꢏꢌꢔ6ꢐ
ꢓ> ,ꢓꢒ/ ꢏꢌꢔ<ꢐ
,1ꢒ6 ꢏꢎꢔꢐ
ꢓ/
,ꢓꢒ6 ꢏꢌꢔ1ꢐ
,1ꢒ/ ꢏꢜBꢍꢐ
,1ꢒ> ꢏꢜꢍꢄꢐ
ꢓ6 ,ꢓꢒ< ꢏꢌꢔꢓꢐ
ꢓ< ,ꢓꢒ1 ꢏꢌꢔꢔꢐ
ꢓ1
5ꢎꢌ9ꢓ ꢔ=
,ꢓꢒꢓ ꢏꢌꢔꢕꢐ
5ꢎꢌ9ꢔ
ꢔꢖ
ꢓꢕ
ꢓꢓ
ꢓꢔ
,ꢓꢒꢔ ꢏꢌꢖꢐ
,ꢓꢒꢕ ꢏꢌ=ꢐ
;
ꢃꢃ
Figure 4. Pin Out of the 8051 Microcontroller
Port 1 (P1.0 - P1.7)
ꢎꢈꢊ =ꢕ6ꢔ• ꢀ 'ꢞꢉ%(%ꢘ% ꢞ+ < =ꢜꢚ(ꢘ #.ꢂ ꢗꢞꢛꢘ%ꢒ ꢃꢞꢙꢊ ꢞ+ ꢘꢈꢊ%ꢊ
ꢗꢞꢛꢘ% ꢈꢆꢑꢊ ꢆꢇꢘꢊꢛꢉꢆꢘꢊ +ꢅꢉ'ꢘ(ꢞꢉ%" ꢆ% ꢝ(ꢇꢇ ꢚꢊ $(%'ꢅ%%ꢊ$ ꢈꢊꢛꢊꢒ
,ꢞꢛꢘ ꢔ (% ꢆ $ꢊ$('ꢆꢘꢊ$ #.ꢂ ꢗꢞꢛꢘ ꢞꢉ ꢗ(ꢉ% ꢔ ꢜ =ꢒ ꢎꢈꢊ ꢗ(ꢉ%"
$ꢊ%(-ꢉꢆꢘꢊ$ ꢆ% ,ꢔꢒꢕ" ,ꢔꢒꢔ" ,ꢔꢒꢓ" ꢒꢒꢒ" ꢆꢛꢊ ꢆꢑꢆ(ꢇꢆꢚꢇꢊ +ꢞꢛ
(ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢆ% ꢛꢊEꢅ(ꢛꢊ$ꢒ 7ꢞ ꢆꢇꢘꢊꢛꢉꢆꢘ(ꢑꢊ +ꢅꢉ'ꢘ(ꢞꢉ% ꢆꢛꢊ
ꢆ%%(-ꢉꢊ$ +ꢞꢛ ,ꢞꢛꢘ ꢔ ꢗ(ꢉ%L ꢘꢈꢅ% ꢘꢈꢊ& ꢆꢛꢊ ꢅ%ꢊ$ %ꢞꢇꢊꢇ& +ꢞꢛ
(ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢞ ꢊ!ꢘꢊꢛꢉꢆꢇ $ꢊꢑ('ꢊ%ꢒ 2!'ꢊꢗꢘ(ꢞꢉ% ꢆꢛꢊ ꢘꢈꢊ
=ꢕ1ꢓ.=ꢕ6ꢓ #ꢀ%" ꢝꢈ('ꢈ ꢅ%ꢊ ,ꢔꢒꢕ ꢆꢉ$ ,ꢔꢒꢔ ꢊ(ꢘꢈꢊꢛ ꢆ% #.ꢂ
ꢇ(ꢉꢊ% ꢞꢛ ꢆ% ꢊ!ꢘꢊꢛꢉꢆꢇ (ꢉꢗꢅꢘ% ꢘꢞ ꢘꢈꢊ ꢘꢈ(ꢛ$ ꢘ(ꢙꢊꢛꢒ
Port 0 (P0.0 - P0.7)
ꢎꢈ(% ꢗꢞꢛꢘ (% ꢆ $ꢅꢆꢇꢜꢗꢅꢛꢗꢞ%ꢊ ꢗꢞꢛꢘ ꢞꢉ ꢗ(ꢉ% 1ꢓ ꢜ 1ꢖ ꢞ+ ꢘꢈꢊ =ꢕ6ꢔ
#ꢀꢒ #ꢉ ꢙ(ꢉ(ꢙꢆꢇ 'ꢞꢙꢗꢞꢉꢊꢉꢘ $ꢊ%(-ꢉ%" (ꢘ (% ꢅ%ꢊ$ ꢆ% ꢆ -ꢊꢉꢊꢛꢆꢇ
ꢗꢅꢛꢗꢞ%ꢊ #.ꢂ ꢗꢞꢛꢘꢒ ꢞꢛ ꢇꢆꢛ-ꢊꢛ $ꢊ%(-ꢉ% ꢝ(ꢘꢈ ꢊ!ꢘꢊꢛꢉꢆꢇ
ꢙꢊꢙꢞꢛ&" (ꢘ ꢚꢊ'ꢞꢙꢊ% ꢆ ꢙꢅꢇꢘ(ꢗꢇꢊ!ꢊ$ ꢆ$$ꢛꢊ%% ꢆꢉ$ $ꢆꢘꢆ ꢚꢅ%
ꢏꢌꢄꢕ ꢜ ꢌꢄ>ꢐꢒ
Port 2 (P2.0 - P2.7)
,ꢞꢛꢘ ꢓ ꢏ,(ꢉ% ꢓꢔ ꢜ ꢓ=ꢐ (% ꢆ $ꢅꢆꢇꢜꢗꢅꢛꢗꢞ%ꢊ ꢗꢞꢛꢘ ꢘꢈꢆꢘ 'ꢆꢉ
+ꢅꢉ'ꢘ(ꢞꢉ ꢆ% -ꢊꢉꢊꢛꢆꢇ ꢗꢅꢛꢗꢞ%ꢊ #.ꢂ" ꢞꢛ ꢆ% ꢘꢈꢊ ꢈ(-ꢈ ꢚ&ꢘꢊ ꢞ+ ꢘꢈꢊ
ꢆ$$ꢛꢊ%% ꢚꢅ% +ꢞꢛ $ꢊ%(-ꢉ% ꢝ(ꢘꢈ ꢊ!ꢘꢊꢛꢉꢆꢇ 'ꢞ$ꢊ ꢙꢊꢙꢞꢛ& ꢞ+
ꢙꢞꢛꢊ ꢘꢈꢆꢉ ꢓ6/ ꢚ&ꢘꢊ% ꢞ+ ꢊ!ꢘꢊꢛꢉꢆꢇ $ꢆꢘꢆ ꢙꢊꢙꢞꢛ& ꢏꢌ= ꢜ ꢌꢔ6ꢐꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢓ<
XR88C681
Port 3
,ꢞꢛꢘ 1 (% ꢆ $ꢅꢆꢇꢜꢗꢅꢛꢗꢞ%ꢊ ꢗꢞꢛꢘ ꢞꢉ ꢗ(ꢉ% ꢔꢕ ꢜ ꢔ>ꢒ #ꢉ ꢆ$$(ꢘ(ꢞꢉ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ(ꢉ- ꢆ% -ꢊꢉꢊꢛꢆꢇ ꢗꢅꢛꢗꢞ%ꢊ #.ꢂ" ꢘꢈꢊ%ꢊ ꢗ(ꢉ% ꢈꢆꢑꢊ ꢙꢅꢇꢘ(ꢗꢇꢊ
+ꢅꢉ'ꢘ(ꢞꢉ%ꢒ 2ꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ ꢗ(ꢉ% ꢈꢆꢑꢊ ꢆꢉ ꢆꢇꢘꢊꢛꢉꢆꢘꢊ ꢗꢅꢛꢗꢞ%ꢊ" ꢆ% ꢇ(%ꢘꢊ$ (ꢉ Table 8ꢒ
Alternate Function
Bit
Name
ꢍ5ꢄ
ꢎ5ꢄ
ꢜ#7ꢎꢕ
ꢜ#7ꢎꢔ
ꢎꢕ
ꢍꢊ'ꢊ(ꢑꢊ ꢄꢆꢘꢆ +ꢞꢛ ꢃꢊꢛ(ꢆꢇ ,ꢞꢛꢘ
ꢎꢛꢆꢉ%ꢙ(ꢘ ꢄꢆꢘꢆ +ꢞꢛ ꢃꢊꢛ(ꢆꢇ ,ꢞꢛꢘ
2!ꢘꢊꢛꢉꢆꢇ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢕ
,1ꢒꢕ
,1ꢒꢔ
,1ꢒꢓ
,1ꢒ1
,1ꢒ<
,1ꢒ6
,1ꢒ/
,1ꢒ>
2!ꢘꢊꢛꢉꢆꢇ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢔ
ꢎ(ꢙꢊꢛ.ꢀꢞꢅꢉꢘꢊꢛ ꢕ 2!ꢘꢊꢛꢉꢆꢇ #ꢉꢗꢅꢘ
ꢎ(ꢙꢊꢛ.ꢀꢞꢅꢉꢘꢊꢛ ꢔ 2!ꢘꢊꢛꢉꢆꢇ #ꢉꢗꢅꢘ
2!ꢘꢊꢛꢉꢆꢇ ꢄꢆꢘꢆ ꢁꢊꢙꢞꢛ& Bꢛ(ꢘꢊ ꢃꢘꢛꢞꢚꢊ
2!ꢘꢊꢛꢉꢆꢇ ꢄꢆꢘꢆ ꢁꢊꢙꢞꢛ& ꢍꢊꢆ$ ꢃꢘꢛꢞꢚꢊ
ꢎꢔ
ꢜBꢍ
ꢜꢍꢄ
Table 8. Alternate Functions of Port 3 Pins
ꢎꢈꢊ =ꢕ6ꢔ ꢆꢇ%ꢞ ꢈꢆ% ꢉꢅꢙꢊꢛꢞꢅ% ꢆ$$(ꢘ(ꢞꢉꢆꢇ ꢗ(ꢉ% ꢝꢈ('ꢈ ꢆꢛꢊ
ꢛꢊꢇꢊꢑꢆꢉꢘ ꢘꢞ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢞ ꢘꢈꢊ 5ꢍ==ꢀ/=ꢔ ꢄꢋꢌꢍꢎ ꢞꢛ ꢞꢘꢈꢊꢛ
ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ%ꢒ ꢎꢈꢊ%ꢊ ꢗ(ꢉ% ꢆꢛꢊ4
Interrupt
Location
ꢜ#7ꢎꢕ
ꢜ#7ꢎꢔ
ꢕꢕꢕ18
ꢕꢕꢔ18
ALE - Address Latch Enable
Table 9. Interrupt Service Routine locations (in
Code Memory) for ꢜINT0 and ꢜINT1
#+ ,ꢞꢛꢘ ꢕ (% ꢅ%ꢊ$ (ꢉ (ꢘ% ꢆꢇꢘꢊꢛꢉꢆꢘꢊ ꢙꢞ$ꢊ ꢜ ꢆ% ꢘꢈꢊ $ꢆꢘꢆ ꢚꢅ% ꢆꢉ$
ꢘꢈꢊ ꢇꢞꢝꢊꢛ ꢚ&ꢘꢊ ꢞ+ ꢘꢈꢊ ꢆ$$ꢛꢊ%% ꢚꢅ% ꢜꢜ ꢌ92 (% ꢘꢈꢊ %(-ꢉꢆꢇ ꢘꢈꢆꢘ
ꢇꢆꢘ'ꢈꢊ% ꢘꢈꢊ ꢆ$$ꢛꢊ%% (ꢉꢘꢞ ꢆꢉ ꢊ!ꢘꢊꢛꢉꢆꢇ ꢛꢊ-(%ꢘꢊꢛ $ꢅꢛ(ꢉ- ꢘꢈꢊ
+(ꢛ%ꢘ ꢈꢆꢇ+ ꢞ+ ꢆ ꢙꢊꢙꢞꢛ& '&'ꢇꢊꢒ ꢂꢉ'ꢊ ꢘꢈ(% (% $ꢞꢉꢊ" ꢘꢈꢊ ,ꢞꢛꢘ ꢕ
ꢇ(ꢉꢊ% ꢆꢛꢊ ꢘꢈꢊꢉ ꢆꢑꢆ(ꢇꢆꢚꢇꢊ +ꢞꢛ $ꢆꢘꢆ (ꢉꢗꢅꢘ ꢞꢛ ꢞꢅꢘꢗꢅꢘ $ꢅꢛ(ꢉ- ꢘꢈꢊ
%ꢊ'ꢞꢉ$ ꢈꢆꢇ+ ꢞ+ ꢘꢈꢊ ꢙꢊꢙꢞꢛ& '&'ꢇꢊ" ꢝꢈꢊꢉ ꢘꢈꢊ $ꢆꢘꢆ ꢘꢛꢆꢉ%+ꢊꢛ
ꢘꢆ3ꢊ% ꢗꢇꢆ'ꢊꢒ
ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" (+ ꢘꢈꢊ ꢅ%ꢊꢛ (% ꢅ%(ꢉ- ꢊ(ꢘꢈꢊꢛ ꢞꢉꢊ ꢞ+ ꢘꢈꢊ%ꢊ (ꢉꢗꢅꢘ% ꢆ%
ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘ" ꢘꢈꢊꢉ ꢘꢈꢊ ꢅ%ꢊꢛ ꢙꢅ%ꢘ (ꢉ%ꢅꢛꢊ ꢘꢈꢆꢘ
ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ ꢞꢛ ꢆꢉ
ꢅꢉ'ꢞꢉ$(ꢘ(ꢞꢉꢆꢇ ꢚꢛꢆꢉ'ꢈ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ ꢏꢘꢞ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ
ꢛꢞꢅꢘ(ꢉꢊꢐ (% ꢇꢞ'ꢆꢘꢊ$ ꢆꢘ ꢞꢉꢊ ꢞ+ ꢘꢈꢊ%ꢊ ꢆ$$ꢛꢊ%% ꢇꢞ'ꢆꢘ(ꢞꢉ%ꢒ
#+ ꢘꢈꢊ =ꢕ6ꢔ• ꢀ (% ꢛꢊEꢅ(ꢛꢊ$ ꢘꢞ (ꢉꢘꢊꢛ+ꢆ'ꢊ ꢘꢞ ꢊ!ꢘꢊꢛꢉꢆꢇ
'ꢞꢙꢗꢞꢉꢊꢉꢘ% (ꢉ ꢘꢈꢊ $ꢆꢘꢆ ꢙꢊꢙꢞꢛ& %ꢗꢆ'ꢊ ꢞ+ %(Iꢊ% -ꢛꢊꢆꢘꢊꢛ
ꢘꢈꢆꢉ ꢓ6/ ꢚ&ꢘꢊ%" ꢘꢈꢊꢉ ꢚꢞꢘꢈ ,ꢞꢛꢘ% ꢕ ꢆꢉ$ ,ꢞꢛꢘ ꢓ ꢙꢅ%ꢘ ꢚꢊ ꢅ%ꢊ$
ꢆ% ꢘꢈꢊ ꢆ$$ꢛꢊ%% ꢆꢉ$ $ꢆꢘꢆ ꢇ(ꢉꢊ%ꢒ ,ꢞꢛꢘ ꢕ ꢝ(ꢇꢇ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢆ
ꢙꢅꢇꢘ(ꢗꢇꢊ!ꢊ$ ꢆ$$ꢛꢊ%%.$ꢆꢘꢆ ꢚꢅ%ꢒ ꢄꢅꢛ(ꢉ- ꢘꢈꢊ +(ꢛ%ꢘ ꢈꢆꢇ+ ꢞ+ ꢆ
ꢙꢊꢙꢞꢛ& '&'ꢇꢊ" ,ꢞꢛꢘ ꢕ ꢝ(ꢇꢇ ꢞꢗꢊꢛꢆꢘꢊ ꢆ% ꢘꢈꢊ ꢇꢞꢝꢊꢛ ꢆ$$ꢛꢊ%%
ꢚ&ꢘꢊꢒ ꢄꢅꢛ(ꢉ- ꢘꢈꢊ %ꢊ'ꢞꢉ$ ꢈꢆꢇ+ ꢞ+ ꢘꢈꢊ ꢙꢊꢙꢞꢛ& '&'ꢇꢊ ,ꢞꢛꢘ ꢕ
ꢝ(ꢇꢇ ꢞꢗꢊꢛꢆꢘꢊ ꢆ% ꢘꢈꢊ ꢚ(ꢜ$(ꢛꢊ'ꢘ(ꢞꢉꢆꢇ $ꢆꢘꢆ ꢚꢅ%ꢒ ,ꢞꢛꢘ ꢓ ꢝ(ꢇꢇ ꢚꢊ
ꢅ%ꢊ$ ꢆ% ꢘꢈꢊ ꢅꢗꢗꢊꢛ ꢆ$$ꢛꢊ%% ꢚ&ꢘꢊꢒ ꢌ92 ꢆꢉ$ ꢘꢈꢊ ꢅ%ꢊ ꢞ+ ꢆ
><9ꢃ1>1 ꢘꢛꢆꢉ%ꢗꢆꢛꢊꢉꢘ ꢇꢆꢘ'ꢈ $ꢊꢑ('ꢊ 'ꢆꢉ ꢚꢊ ꢅ%ꢊ$ ꢘꢞ
$ꢊꢙꢅꢇꢘ(ꢗꢇꢊ! ꢘꢈꢊ ꢌ$$ꢛꢊ%% ꢆꢉ$ ꢄꢆꢘꢆ ꢚꢅ% %(-ꢉꢆꢇ%ꢒ
ꢜINT0 (P3.2) and ꢜINT1 (P3.3)
ꢜ#7ꢎꢕ ꢆꢉ$ ꢜ#7ꢎꢔ ꢆꢛꢊ ꢊ!ꢘꢊꢛꢉꢆꢇ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘ% ꢘꢞ
ꢘꢈꢊ =ꢕ6ꢔ• ꢀꢒ 2ꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗ(ꢉ% %ꢅꢗꢗꢞꢛꢘ C$(ꢛꢊ'ꢘ
(ꢉꢘꢊꢛꢛꢅꢗꢘD ꢗꢛꢞ'ꢊ%%(ꢉ-ꢒ #ꢉ ꢘꢈ(% 'ꢆ%ꢊ" ꢘꢈꢊ ꢘꢊꢛꢙ C$(ꢛꢊ'ꢘD
ꢙꢊꢆꢉ% ꢘꢈꢆꢘ (+ ꢞꢉꢊ ꢞ+ ꢘꢈꢊ%ꢊ (ꢉꢗꢅꢘ% ꢆꢛꢊ ꢆ%%ꢊꢛꢘꢊ$" ꢘꢈꢊꢉ
ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢝ(ꢇꢇ ꢆꢅꢘꢞꢙꢆꢘ('ꢆꢇꢇ& ꢚꢛꢆꢉ'ꢈ ꢘꢞ ꢆ %ꢗꢊ'(+('
ꢏ+(!ꢊ$ꢐ ꢇꢞ'ꢆꢘ(ꢞꢉ (ꢉ 'ꢞ$ꢊ ꢙꢊꢙꢞꢛ&ꢒ ꢎꢈ(% ꢇꢞ'ꢆꢘ(ꢞꢉ (%
$ꢊꢘꢊꢛꢙ(ꢉꢊ$ ꢚ& ꢘꢈꢊ '(ꢛ'ꢅ(ꢘ $ꢊ%(-ꢉ ꢞ+ ꢘꢈꢊ =ꢕ6ꢔ• ꢀ #ꢀ ꢆꢉ$
'ꢆꢉꢉꢞꢘ ꢚꢊ 'ꢈꢆꢉ-ꢊ$ꢒ Table 9 ꢗꢛꢊ%ꢊꢉꢘ% ꢘꢈꢊ ꢇꢞ'ꢆꢘ(ꢞꢉ ꢏ(ꢉ
'ꢞ$ꢊ ꢙꢊꢙꢞꢛ&ꢐ ꢘꢈꢆꢘ ꢘꢈꢊ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢝ(ꢇꢇ ꢚꢛꢆꢉ'ꢈ ꢘꢞ" (+
ꢊ(ꢘꢈꢊꢛ ꢞ+ ꢘꢈꢊ%ꢊ (ꢉꢗꢅꢘ% ꢆꢛꢊ ꢆ%%ꢊꢛꢘꢊ$ꢒ
Figure 5 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ %'ꢈꢊꢙꢆꢘ(' (ꢇꢇꢅ%ꢘꢛꢆꢘ(ꢉ- ꢈꢞꢝ ꢘꢈꢊ
5ꢍ==ꢀ/=ꢔ ꢄꢋꢌꢍꢎ 'ꢆꢉ ꢚꢊ (ꢉꢘꢊꢛ+ꢆ'ꢊ$ ꢘꢞ ꢘꢈꢊ =ꢕ6ꢔ• ꢀꢒ
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ꢙꢊꢙꢞꢛ& %ꢗꢆ'ꢊ" ꢝꢈꢊꢛꢊ ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ
ꢛꢞꢅꢘ(ꢉꢊ ꢊ!(%ꢘ%ꢒ Table 10 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ ꢇ(%ꢘ ꢞ+ ꢘꢈꢊ%ꢊ ꢍ2ꢃꢎꢌꢍꢎ
(ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ%" ꢘꢈꢊ ꢞꢗꢜ'ꢞ$ꢊ%" ꢆꢉ$ ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ-
ꢍ2ꢃꢎꢌꢍꢎ ꢆ$$ꢛꢊ%%ꢒ
Interfacing the 8080 CPU Module to the XR88C681
DUART for Interrupt Processing
ꢎꢈꢊ =ꢕ=ꢕꢌ ꢀ,ꢋ 'ꢆꢉ ꢚꢊ 'ꢞꢉꢉꢊ'ꢘꢊ$ ꢘꢞ ꢘꢈꢊ 5ꢍ==ꢀ/=ꢔ ꢆꢉ$
ꢛꢅꢉ (ꢉ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢄꢛ(ꢑꢊꢉ ꢙꢞ$ꢊꢒ Figure 7 ꢗꢛꢊ%ꢊꢉꢘ% ꢆꢉ
ꢆꢗꢗꢛꢞꢆ'ꢈ ꢘꢈꢆꢘ 'ꢆꢉ ꢚꢊ ꢆꢗꢗꢇ(ꢊ$ ꢘꢞ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢈꢊ
5ꢍ==ꢀ/=ꢔ ꢄꢋꢌꢍꢎ ꢘꢞ ꢘꢈꢊ =ꢕ=ꢕꢌ ꢀ,ꢋ +ꢞꢛ Cꢊ!ꢘꢊꢛꢉꢆꢇD
ꢑꢊ'ꢘꢞꢛꢊ$ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛꢞ'ꢊ%%(ꢉ-ꢒ Please note that (-ꢅꢛꢊ =
only includes information pertaining to DUART interrupt
servicing. ꢂꢘꢈꢊꢛ '(ꢛ'ꢅ(ꢘꢛ& ꢏ%ꢅ'ꢈ ꢆ% ꢘꢈꢊ =ꢓꢓ< ꢀꢇꢞ'3
0ꢊꢉꢊꢛꢆꢘꢞꢛ" ꢘꢈꢊ ꢌ$$ꢛꢊ%% *ꢅ%" ꢊꢘ'ꢒꢐ ꢈꢆꢑꢊ ꢚꢊꢊꢉ ꢞꢙ(ꢘꢘꢊ$ +ꢛꢞꢙ
ꢘꢈꢊ %'ꢈꢊꢙꢆꢘ('ꢒ #ꢉ ꢘꢈ(% %'ꢈꢊꢙꢆꢘ('" ꢘꢈꢊ ꢄꢋꢌꢍꢎ #ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢃꢊꢛꢑ('ꢊ ꢍꢞꢅꢘ(ꢉꢊ (% ꢇꢞ'ꢆꢘꢊ$ ꢆꢘ ꢕꢕꢓꢕ
(ꢉ ꢙꢊꢙꢞꢛ&ꢒ
ꢔ/
ꢌ$$(ꢘ(ꢞꢉꢆꢇꢇ&" ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢈꢆ% ꢚꢊꢊꢉ 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ ꢞꢗꢊꢛꢆꢘꢊ
(ꢉ ꢘꢈꢊ #ꢜꢁꢞ$ꢊꢒ ꢎꢈꢊ +ꢅꢉ'ꢘ(ꢞꢉ $ꢊ%'ꢛ(ꢗꢘ(ꢞꢉ ꢞ+ ꢘꢈ(% '(ꢛ'ꢅ(ꢘ (%
ꢗꢛꢊ%ꢊꢉꢘꢊ$ ꢈꢊꢛꢊꢒ
Op-Code (hex)
Mnemonic
Restart Address
(hex)
ꢎꢈꢊ 5ꢍ==ꢀ/=ꢔ ꢝ(ꢇꢇ ꢛꢊEꢅꢊ%ꢘ ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢘꢞ ꢘꢈꢊ =ꢕ=ꢕꢌ
ꢀ,ꢋ" ꢚ& ꢘꢞ--ꢇ(ꢉ- (ꢘ% ꢜ#7ꢎꢍ ꢞꢅꢘꢗꢅꢘ CꢇꢞꢝDꢒ ꢎꢈ(% %(-ꢉꢆꢇ (%
(ꢉꢑꢊꢛꢘꢊ$ ꢆꢉ$ ꢆꢗꢗꢇ(ꢊ$ ꢘꢞ ꢘꢈꢊ ꢆ'ꢘ(ꢑꢊꢜꢈ(-ꢈ #7ꢎ (ꢉꢗꢅꢘ ꢞ+ ꢘꢈꢊ
ꢀ,ꢋꢒ ꢂꢉ'ꢊ ꢘꢈꢊ =ꢕ=ꢕꢌ ꢀ,ꢋ ꢈꢆ% 'ꢞꢙꢗꢇꢊꢘꢊ$ (ꢘ% 'ꢅꢛꢛꢊꢉꢘ
(ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ" (ꢘ ꢝ(ꢇꢇ ꢆ%%ꢊꢛꢘ ꢘꢈꢊ ꢆ'ꢘ(ꢑꢊꢜꢇꢞꢝ ꢜ#7ꢎꢌ %(-ꢉꢆꢇ ꢏ+ꢛꢞꢙ
ꢘꢈꢊ =ꢓꢓ= *(ꢜꢄ(ꢛꢊ'ꢘ(ꢞꢉꢆꢇ *ꢅ% ꢄꢛ(ꢑꢊꢛꢐꢒ ꢌꢘ ꢘꢈ(% ꢘ(ꢙꢊ" ꢚꢞꢘꢈ ꢘꢈꢊ
ꢜ#7ꢎꢍ %(-ꢉꢆꢇ ꢏ+ꢛꢞꢙ ꢘꢈꢊ ꢄꢋꢌꢍꢎꢐ ꢆꢉ$ ꢘꢈꢊ ꢜ#7ꢎꢌ %(-ꢉꢆꢇ
ꢏ+ꢛꢞꢙ ꢘꢈꢊ =ꢓꢓ=ꢐ ꢆꢛꢊ ꢊꢆ'ꢈ ꢆꢘ ꢆ ꢇꢞ-(' CꢇꢞꢝDꢒ ꢎꢈꢊ ꢜ#7ꢎꢍ ꢆꢉ$
ꢜ#7ꢎꢌ %(-ꢉꢆꢇ% ꢆꢛꢊ ꢚꢞꢘꢈ ꢛꢞꢅꢘꢊ$ ꢘꢞ ꢆ ꢘꢝꢞꢜ(ꢉꢗꢅꢘ ꢂꢍ -ꢆꢘꢊꢒ
8ꢊꢉ'ꢊ" ꢝꢈꢊꢉ ꢚꢞꢘꢈ ꢜ#7ꢎꢍ ꢆꢉ$ ꢜ#7ꢎꢌ ꢆꢛꢊ ꢆꢘ ꢇꢞ-(' CꢇꢞꢝD" ꢘꢈꢊ
ꢞꢅꢘꢗꢅꢘ ꢞ+ ꢘꢈꢊ ꢂꢍꢜ-ꢆꢘꢊ ꢝ(ꢇꢇ ꢆꢇ%ꢞ ꢚꢊ ꢆꢘ ꢆ ꢇꢞ-(' CꢇꢞꢝD" ꢆꢉ$
ꢘꢈꢊꢛꢊꢚ& ꢆ%%ꢊꢛꢘ(ꢉ- ꢚꢞꢘꢈ ꢞ+ ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ 2ꢉꢆꢚꢇꢊ ꢏꢂ2ꢐ (ꢉꢗꢅꢘ%
ꢞ+ ꢘꢈꢊ ꢃ7><9ꢃꢓ<< ꢄꢆꢘꢆ *ꢅ% ꢚꢅ++ꢊꢛ ꢏꢋ1ꢐꢒ ꢎꢈ(% Cꢂꢍ(ꢉ-D ꢞ+
ꢘꢈꢊ ꢜ#7ꢎꢍ ꢆꢉ$ ꢜ#7ꢎꢌ %(-ꢉꢆꢇ% (% ꢅ%ꢊ$ ꢘꢞ (ꢉ%ꢅꢛꢊ ꢘꢈꢆꢘ ꢞꢉꢇ& ꢘꢈꢊ
ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ ꢛꢊEꢅꢊ%ꢘ(ꢉ- ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ (% ꢘꢈꢊ ꢞꢉꢊ ꢘꢈꢆꢘ
ꢛꢊ'ꢊ(ꢑꢊ% ꢘꢈꢊ %ꢊꢛꢑ('ꢊ ꢏꢊꢒ-ꢒ" ꢛꢊ%ꢗꢞꢉ%(ꢑꢊ ꢘꢞ ꢘꢈꢊ ꢆ%%ꢊꢛꢘꢊ$
ꢜ#7ꢎꢌ %(-ꢉꢆꢇꢐꢒ ꢂꢉ'ꢊ ꢚꢞꢘꢈ ꢜꢂ2 (ꢉꢗꢅꢘ% ꢞ+ ꢋ1 ꢆꢛꢊ ꢆ%%ꢊꢛꢘꢊ$"
ꢘꢈꢊ $ꢆꢘꢆ" ꢆꢗꢗꢇ(ꢊ$ ꢆꢘ ꢘꢈꢊ (ꢉꢗꢅꢘ ꢞ+ ꢘꢈ(% $ꢊꢑ('ꢊ ꢏꢋ1ꢐ ꢝ(ꢇꢇ ꢉꢞꢝ
ꢆꢗꢗꢊꢆꢛ ꢆꢘ ꢘꢈꢊ ꢞꢅꢘꢗꢅꢘ ꢞ+ ꢘꢈ(% $ꢊꢑ('ꢊ" ꢆꢉ$ ꢆꢘ ꢘꢈꢊ ꢄ> ꢜ ꢄꢕ
(ꢉꢗꢅꢘ% ꢞ+ ꢘꢈꢊ =ꢓꢓ= $ꢊꢑ('ꢊ ꢏꢋꢓꢐꢒ Please note that, in this
ꢀ>
ꢀ
ꢄ>
ꢄ
2>
2
>
ꢍꢃꢎ ꢕ
ꢍꢃꢎ ꢔ
ꢍꢃꢎ ꢓ
ꢍꢃꢎ 1
ꢍꢃꢎ <
ꢍꢃꢎ 6
ꢍꢃꢎ /
ꢍꢃꢎ >
ꢕꢕꢕꢕ
ꢕꢕꢕ=
ꢕꢕꢔꢕ
ꢕꢕꢔ=
ꢕꢕꢓꢕ
ꢕꢕꢓ=
ꢕꢕ1ꢕ
ꢕꢕ1=
Table 10. 8080A and 8085 CPU Restart Instructions
Used With Vectored Interrupts
ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢞꢉ'ꢊ ꢘꢈꢊ ꢀ,ꢋ ꢛꢊ'ꢊ(ꢑꢊ% ꢘꢈꢊ ꢞꢗꢜ'ꢞ$ꢊ +ꢞꢛ ꢞꢉꢊ ꢞ+
ꢘꢈꢊ%ꢊ ꢍ2ꢃꢎꢌꢍꢎ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ%" (ꢘ ꢝ(ꢇꢇ ꢚꢊ-(ꢉ ꢊ!ꢊ'ꢅꢘ(ꢉ- ꢘꢈ(%
(ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ ꢚ& ꢇꢞꢆ$(ꢉ- ꢘꢈꢊ ,ꢛꢞ-ꢛꢆꢙ ꢀꢞꢅꢉꢘꢊꢛ ꢝ(ꢇꢇ ꢘꢈꢊ
ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ Cꢍꢊ%ꢘꢆꢛꢘ ꢌ$$ꢛꢊ%%Dꢒ ꢌ+ꢘꢊꢛꢝꢆꢛ$%" ꢗꢛꢞ-ꢛꢆꢙ
'ꢞꢉꢘꢛꢞꢇ ꢝ(ꢇꢇ ꢚꢊ ꢚꢛꢆꢉ'ꢈꢊ$ ꢘꢞ ꢘꢈꢊ Cꢍꢊ%ꢘꢆꢛꢘ ꢌ$$ꢛꢊ%%D ꢇꢞ'ꢆꢘ(ꢞꢉꢒ
example, the value “E7 ” is hard-wired into the input of
U3ꢒ ꢎꢈ(% ꢑꢆꢇꢅꢊ (% ꢘꢈꢊ ꢞꢗꢜ'ꢞ$ꢊ +ꢞꢛ ꢘꢈꢊ Cꢍꢃꢎ <D 'ꢞꢙꢙꢆꢉ$ꢒ
8ꢊꢉ'ꢊ" ꢞꢉ'ꢊ ꢘꢈ(% $ꢆꢘꢆ (% -ꢆꢘꢊ$ (ꢉꢘꢞ ꢘꢈꢊ ꢀ,ꢋ ꢙꢞ$ꢅꢇꢊ" ꢑ(ꢆ
16
ꢞꢛ 2!ꢆꢙꢗꢇꢊ4
#+ ꢘꢈꢊ ꢞꢗꢜ'ꢞ$ꢊ C2> D (% ꢇꢞꢆ$ꢊ$ ꢞꢉꢘꢞ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ% $ꢅꢛ(ꢉ-
ꢔ/
ꢘꢈꢊ ꢜ#7ꢎꢌ '&'ꢇꢊ" ꢘꢈ(% ꢞꢗꢜ'ꢞ$ꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$% ꢝ(ꢘꢈ ꢘꢈꢊ Cꢍꢃꢎ
<D 'ꢞꢙꢙꢆꢉ$ ꢆꢉ$" ꢘꢈꢊ ꢀ,ꢋ ꢝ(ꢇꢇ ꢇꢞꢆ$ ꢕꢕꢓꢕ (ꢉꢘꢞ ꢘꢈꢊ
ꢘꢈꢊ $ꢆꢘꢆ ꢚꢅ%" ꢘꢈꢊ ꢀ,ꢋ ꢝ(ꢇꢇ ꢇꢞꢆ$ ꢕꢕꢓꢕ (ꢉꢘꢞ (ꢘ% ,ꢛꢞ-ꢛꢆꢙ
ꢔ/
ꢀꢞꢅꢉꢘꢊꢛ ꢆꢉ$ ꢚꢛꢆꢉ'ꢈ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢘꢞ ꢘꢈꢆꢘ ꢇꢞ'ꢆꢘ(ꢞꢉꢒ ꢎꢈꢊ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢊꢛꢑ('ꢊ ꢍꢞꢅꢘ(ꢉꢊ +ꢞꢛ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢊ!(%ꢘ% ꢆꢘ ꢘꢈ(%
ꢇꢞ'ꢆꢘ(ꢞꢉ (ꢉ ꢙꢊꢙꢞꢛ&ꢒ
ꢔ/
,ꢛꢞ-ꢛꢆꢙ ꢀꢞꢅꢉꢘꢊꢛ ꢆꢉ$ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢝ(ꢇꢇ ꢚꢛꢆꢉ'ꢈ ꢘꢞ ꢘꢈꢆꢘ
ꢇꢞ'ꢆꢘ(ꢞꢉ (ꢉ ꢙꢊꢙꢞꢛ& ꢏ%ꢊꢊ Table 10ꢐꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢓ=
XR88C681
U1
;''
U4
#7ꢎ2
#7ꢎ
ꢋ6
ꢜ#7ꢎꢍ
ꢋ/
;
''
U3
ꢄ*#7
ꢜꢂ2ꢔ ꢜꢂ2ꢓ
8080A CPU
XR88C681
DUART
U2
ꢄ#ꢕ
ꢄ#ꢔ
ꢄ#ꢓ
ꢄ#1
ꢄ#<
ꢄꢂꢕ
ꢄꢕ
ꢄꢔ
ꢄꢓ
ꢄ1
ꢄ<
ꢄꢂꢔ
ꢄꢂꢓ
ꢄꢂ1
ꢄꢂ<
ꢄꢂ6
ꢄꢂ/
ꢄꢂ>
8228
ꢄ#6
ꢄ#/
Bi-Directional
BUS Driver
ꢄ6
ꢄ/
ꢄ>
ꢄ#>
ꢃ7><9ꢃꢓ<<
#7ꢎꢌ
Figure 7. Circuit Schematic depicting approach to Interface the XR88C681 DUART
to the 8080A CPU, for “External” Vectored Interrupt Processing
(Interrupt Service Routine resides at 0020 in Memory)
16
ꢃ(ꢉ'ꢊ ꢘꢈꢊ =ꢕ=ꢕꢌ ꢀ,ꢋ 'ꢆꢉ %ꢅꢗꢗꢞꢛꢘ ꢅꢗ ꢘꢞ = $(++ꢊꢛꢊꢉꢘ ꢍꢃꢎ
(ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ%" (ꢘ 'ꢆꢉ %ꢅꢗꢗꢞꢛꢘ ꢅꢗ ꢘꢞ $(++ꢊꢛꢊꢉꢘ
ꢞ+ ꢘꢈꢊ ꢆ$ꢑꢆꢉ'ꢊꢙꢊꢉꢘ% ꢘꢈꢆꢘ ꢝꢊꢛꢊ ꢙꢆ$ꢊ (ꢉ ꢘꢈꢊ ꢘꢛꢆꢉ%(ꢘ(ꢞꢉ
+ꢛꢞꢙ ꢘꢈꢊ =ꢕ=ꢕꢌ ꢘꢞ ꢘꢈꢊ =ꢕ=6 (ꢉ'ꢇꢅ$ꢊ 'ꢞꢙꢚ(ꢉ(ꢉ- ꢘꢈꢊ ꢀꢇꢞ'3
0ꢊꢉꢊꢛꢆꢘꢞꢛ +ꢅꢉ'ꢘ(ꢞꢉ% ꢞ+ ꢘꢈꢊ =ꢓꢓ< ꢞꢉꢘꢞ ꢘꢈꢊ ꢀ,ꢋ 'ꢈ(ꢗ"
ꢆ$$(ꢉ- ꢆ ꢉꢞꢉꢜꢙꢆ%3ꢆꢚꢇꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ" ꢆ$$(ꢉ- 1
C$(ꢛꢊ'ꢘD (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘ ꢗ(ꢉ%" ꢆꢉ$ ꢆ$$(ꢉ- %ꢞꢙꢊ
+ꢞꢛꢙ ꢞ+ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛ(ꢞꢛ(ꢘ&ꢒ ꢎꢈꢊ =ꢕ=6 %ꢘ(ꢇꢇ ꢛꢊEꢅ(ꢛꢊ% %ꢞꢙꢊ -ꢇꢅꢊ
ꢇꢞ-(' (ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ ꢗꢛꢞ$ꢅ'ꢊ ꢘꢈꢊ ꢀꢞꢉꢘꢛꢞꢇ *ꢅ% %(-ꢉꢆꢇ% ꢏ(ꢒꢊꢒ"
ꢜ#ꢂꢍ" ꢜ#ꢂB" ꢜꢁ2ꢁꢍ" ꢜꢁ2ꢁBꢐꢒ ꢅꢛꢘꢈꢊꢛ" (ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ
ꢙ(ꢉ(ꢙ(Iꢊ ꢗ(ꢉ 'ꢞꢅꢉꢘ" ꢘꢈꢊ =ꢕ=6 'ꢞꢉꢘꢆ(ꢉ% ꢆ ꢙꢅꢇꢘ(ꢗꢇꢊ!ꢊ$
ꢌ$$ꢛꢊ%%.ꢄꢆꢘꢆ *ꢅ% ꢏꢌꢄꢕ ꢜ ꢌꢄ>ꢐꢒ ꢃꢗꢊ'(+('ꢆꢇꢇ&" ꢘꢈꢊ ꢇꢞꢝꢊꢛ =
ꢚ(ꢘ% ꢞ+ ꢘꢈꢊ ꢌ$$ꢛꢊ%% *ꢅ% %ꢈꢆꢛꢊ ꢗ(ꢉ% ꢝ(ꢘꢈ ꢘꢈꢊ = ꢚ(ꢘ ꢄꢆꢘꢆ *ꢅ%ꢒ
8ꢊꢉ'ꢊ" ꢆ ><9ꢃ1>1 =ꢜꢚ(ꢘ ꢇꢆꢘ'ꢈ (% ꢉꢊꢊ$ꢊ$ (ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ
$ꢊꢙꢅꢇꢘ(ꢗꢇꢊ! ꢘꢈꢊ ꢌ$$ꢛꢊ%% ꢆꢉ$ ꢄꢆꢘꢆ ꢚꢅ%ꢊ%ꢒ
=
(ꢉꢘꢊꢛꢛꢅꢗꢘꢜ$ꢛ(ꢑꢊꢉ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ%ꢒ ꢎꢈ(% 'ꢆꢉ ꢚꢊ ꢆ'ꢈ(ꢊꢑꢊ$
ꢚ& ꢛꢊꢗꢇ('ꢆꢘ(ꢉ- ꢘꢈꢊ ꢆꢗꢗꢛꢞꢆ'ꢈ" ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ Figure 7" ꢆꢉ$
ꢚ& ꢈꢆꢛ$ꢝ(ꢛ(ꢉ- ꢘꢈꢊ ꢞꢗꢜ'ꢞ$ꢊ% +ꢞꢛ ꢊꢆ'ꢈ ꢞ+ ꢘꢈꢊ ꢍ2ꢃꢎꢌꢍꢎ
(ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ% ꢘꢞ ꢘꢈꢊ (ꢉꢗꢅꢘ% ꢞ+ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ++ꢊꢛ% ꢏ%ꢊꢊ
Table 10ꢐꢒ
ꢎꢈꢊ%ꢊ ꢄꢆꢘꢆ *ꢅ++ꢊꢛ% %ꢈꢞꢅꢇ$ ꢚꢊ ꢊꢉꢆꢚꢇꢊ$ ꢞꢉꢇ& $ꢅꢛ(ꢉ- ꢘꢈꢊ
ꢜ#7ꢎꢌ '&'ꢇꢊ" ꢆꢉ$ ꢞꢉꢇ& ꢝꢈꢊꢉ ꢘꢈꢊ(ꢛ ꢆ%%ꢞ'(ꢆꢘꢊ$ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ
ꢛꢊEꢅꢊ%ꢘꢊ$ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊꢒ
C.6.1.3 8085 Microprocessor
ꢎꢈꢊ =ꢕ=6 ꢀ,ꢋ (% ꢆꢉꢞꢘꢈꢊꢛ ꢊꢆꢛꢇ& #ꢉꢘꢊꢇ ꢙ('ꢛꢞꢗꢛꢞ'ꢊ%%ꢞꢛ"
ꢆꢇꢘꢈꢞꢅ-ꢈ (ꢘ (% ꢙꢞꢛꢊ ꢆ$ꢑꢆꢉ'ꢊ$ ꢘꢈꢆꢉ ꢘꢈꢊ =ꢕ=ꢕꢌ ꢀ,ꢋꢒ ꢃꢞꢙꢊ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢓꢖ
XR88C681
Figure 8 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ %'ꢈꢊꢙꢆꢘ(' ꢞ+ ꢘꢈꢊ =ꢕ=6 ꢀ,ꢋ ꢁꢞ$ꢅꢇꢊꢒ
ꢄꢕ
ꢄꢔ
ꢌꢄꢕ
ꢌꢄꢔ
ꢌꢄꢓ
ꢌꢄ1
ꢌꢄ<
ꢄꢓ
ꢄ1
ꢄ<
ꢌꢄ6
5ꢔ
ꢄ6
ꢄ/
ꢄ>
ꢌꢄ/
ꢌꢄ>
5ꢓ
ꢔ)
ꢓ)
1)
ꢔꢄ
ꢓꢄ
1ꢄ
<ꢄ
6ꢄ
/ꢄ
>ꢄ
=ꢄ
ꢀ
ꢌꢕ
ꢌꢔ
ꢎꢍꢌ,
ꢌꢓ
ꢌ1
ꢌ<
ꢍꢃꢎ >ꢒ6
<)
6)
/)
ꢍꢃꢎ /ꢒ6
ꢍꢃꢎ 6ꢒ6
ꢌ6
ꢌ/
#7ꢎꢍ
>)
=)
ꢌ>
ꢜ#7ꢎꢌ
ꢌ92
74LS373
ꢌ=
ꢌꢖ
ꢌ=
ꢌꢖ
ꢌꢔꢕ
ꢌꢔꢔ
ꢌꢔꢕ
ꢌꢔꢔ
ꢜ#ꢂꢍ
ꢌꢔꢓ
ꢌꢔꢓ
ꢌꢔ1
ꢌꢔ1
ꢌꢔ<
ꢜꢁ2ꢁꢍ
ꢌꢔ<
ꢌꢔ6
ꢌꢔ6
ꢜ#ꢂB
ꢜ#ꢂ.ꢁ
ꢜꢍꢄ
ꢜBꢍ
ꢜꢁ2ꢁB
8085 CPU
Figure 8. A Schematic of the 8085 CPU Module
Figure 9 (ꢇꢇꢅ%ꢘꢛꢆꢘꢊ% ꢆꢉ ꢆꢗꢗꢛꢞꢆ'ꢈ ꢘꢞ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢈꢊ
5ꢍ==ꢀ/=ꢔ ꢄꢋꢌꢍꢎ ꢘꢞ ꢘꢈꢊ =ꢕ=6 ꢀ,ꢋ ꢙꢞ$ꢅꢇꢊꢒ 7ꢞꢘꢊ ꢘꢈꢆꢘ
ꢘꢈꢊ 5ꢍ==ꢀ/=ꢔ ꢄꢋꢌꢍꢎ" (ꢉ ꢘꢈ(% 'ꢆ%ꢊ" (% ꢙꢊꢙꢞꢛ& ꢙꢆꢗꢗꢊ$
ꢏꢊꢒ-ꢒ" ꢘꢈꢊ %(-ꢉꢆꢇ% ꢜꢁ2ꢁꢍ ꢆꢉ$ ꢜꢁ2ꢁB ꢞ+ ꢘꢈꢊ ꢀ,ꢋ ꢙꢞ$ꢅꢇꢊ
ꢆꢛꢊ 'ꢞꢉꢉꢊ'ꢘꢊ$ ꢘꢞ ꢘꢈꢊ ꢜꢍꢄ ꢆꢉ$ ꢜBꢍ ꢗ(ꢉ% ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎꢐꢒ
8ꢞꢝꢊꢑꢊꢛ" ꢘꢈꢊ ꢅ%ꢊꢛ 'ꢞꢅꢇ$ ꢈꢆꢑꢊ Mꢅ%ꢘ ꢆ% ꢊꢆ%(ꢇ& 'ꢞꢉꢉꢊ'ꢘꢊ$ ꢘꢈꢊ
5ꢍ==ꢀ/=ꢔ $ꢊꢑ('ꢊ ꢘꢞ ꢘꢈꢊ ꢀ,ꢋ ꢙꢞ$ꢅꢇꢊH% #.ꢂ ꢗꢞꢛꢘ ꢏꢊꢒ-" ꢘꢈꢊ
%(-ꢉꢆꢇ ꢜ#ꢂꢍ ꢆꢉ$ ꢜ#ꢂB ꢞ+ ꢘꢈꢊ ꢀ,ꢋ ꢙꢞ$ꢅꢇꢊ ꢆꢛꢊ 'ꢞꢉꢉꢊ'ꢘꢊ$
ꢘꢞ ꢘꢈꢊ ꢜꢍꢄ ꢆꢉ$ ꢜBꢍ ꢗ(ꢉ% ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ" ꢛꢊ%ꢗꢊ'ꢘ(ꢑꢊꢇ&ꢐꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
1ꢕ
XR88C681
ꢌꢄꢕ ꢜ ꢌꢄ>
ꢄꢕ ꢜ ꢄ>
ꢌꢕ ꢜ ꢌ1
ꢌꢕ ꢜ ꢌ1
ꢔꢄ ꢜ =ꢄ
ꢔ) ꢜ =)
5ꢔ
ꢜꢀꢃFꢄꢋꢌꢍꢎ
ꢌ< ꢜ ꢌ>
ꢜꢀꢃ
ꢌ92
ꢀ
5ꢓ
74LS373
ꢎꢍꢌ,
ꢍꢃꢎ >ꢒ6
ꢌ= ꢜ ꢌꢔ6
ꢍꢃꢎ /ꢒ6
ꢍꢃꢎ 6ꢒ6
#7ꢎꢍ
Address
Decoder
ꢜꢍꢄ
ꢜ#7ꢎꢌ
ꢌ= ꢜ ꢌꢔ6
ꢜBꢍ
ꢜ#ꢂ.ꢁ
ꢜꢍꢄ
ꢜꢁ2ꢁꢍ
ꢜꢁ2ꢁB
XR88C681
ꢜꢀꢃFꢂꢎ82ꢍF#ꢀ
ꢜBꢍ
8085 CPU
Figure 9. Schematic of the XR88C681 Interface to the 8085 CPU Module (Memory Mapped).
ꢎꢈꢊ ꢄꢋꢌꢍꢎH% ꢜ#7ꢎꢍ ꢗ(ꢉ ꢝꢆ% $ꢊꢇ(ꢚꢊꢛꢆꢘꢊꢇ& ꢞꢙ(ꢘꢘꢊ$ +ꢛꢞꢙ
Figure 9" ꢚꢊ'ꢆꢅ%ꢊ (ꢘ% ꢅ%ꢊ ꢝ(ꢇꢇ ꢚꢊ ꢆ$$ꢛꢊ%%ꢊ$ (ꢉ Figure 10
ꢆꢉ$ Figure 11ꢒ
ꢏꢎꢍꢌ,ꢐꢒ Bꢈꢊꢉ $(%'ꢅ%%(ꢉ- (ꢉꢘꢊꢛ+ꢆ'(ꢉ- +ꢞꢛ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ
%ꢊꢛꢑ('(ꢉ- ꢞ+ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ% %ꢅ'ꢈ ꢆ% ꢘꢈꢊ ꢄꢋꢌꢍꢎ" ꢝꢊ
ꢆꢛꢊ ꢞꢉꢇ& 'ꢞꢉ'ꢊꢛꢉꢊ$ ꢝ(ꢘꢈ ꢘꢈꢊ ꢙꢆ%3ꢆꢚꢇꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ
(ꢉꢗꢅꢘ%ꢒ ꢂ+ ꢘꢈꢊ +ꢞꢅꢛ ꢙꢆ%3ꢆꢚꢇꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘ%L
ꢘꢈꢛꢊꢊ ꢞ+ ꢘꢈꢊ%ꢊ (ꢉꢗꢅꢘ% %ꢅꢗꢗꢞꢛꢘ Cꢄ(ꢛꢊ'ꢘ #ꢉꢘꢊꢛꢛꢅꢗꢘD
8085 CPU Module Interrupt Structure
ꢗꢛꢞ'ꢊ%%(ꢉ-ꢒ
ꢎꢈꢊ ꢛꢊꢙꢆ(ꢉ(ꢉ- ꢞꢉꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ
ꢎꢈꢊ =ꢕ=6 ꢀ,ꢋ %ꢅꢗꢗꢞꢛꢘ% ꢚꢞꢘꢈ ꢄ(ꢛꢊ'ꢘ ꢆꢉ$ C2!ꢘꢊꢛꢉꢆꢇD
;ꢊ'ꢘꢞꢛꢊ$ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛꢞ'ꢊ%%(ꢉ-ꢒ ꢎꢈꢊ =ꢕ=6 ꢈꢆ% < ꢙꢆ%3ꢆꢚꢇꢊ
(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘ% ꢏꢍꢃꢎ 6ꢒ6" ꢍꢃꢎ /ꢒ6" ꢍꢎꢃ >ꢒ6" ꢆꢉ$
#7ꢎꢍꢐ" ꢆꢉ$ ꢔ ꢉꢞꢉꢜꢙꢆ%3ꢆꢚꢇꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘ
%ꢅꢗꢗꢞꢛꢘ% C2!ꢘꢊꢛꢉꢆꢇ ;ꢊ'ꢘꢞꢛꢊ$ #ꢉꢘꢊꢛꢛꢅꢗꢘD ꢗꢛꢞ'ꢊ%%(ꢉ-ꢒ
Table 11 ꢇ(%ꢘ% ꢘꢈꢊ%ꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢍꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘ% ꢆꢉ$ ꢘꢈꢊ(ꢛ
'ꢈꢆꢛꢆ'ꢘꢊꢛ(%ꢘ('%.+ꢊꢆꢘꢅꢛꢊ%ꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
1ꢔ
XR88C681
Input Name
Trigger
Priority
Type
Acknowledge
Signal?
Address (Hex)
ꢍꢃꢎ >ꢒ6
ꢍꢃꢎ /ꢒ6
ꢍꢃꢎ 6ꢒ6
#7ꢎꢍ
,ꢞ%(ꢘ(ꢑꢊ 2$-ꢊ ꢎꢛ(--ꢊꢛꢊ$
8(-ꢈ 9ꢊꢑꢊꢇ ꢋꢉꢘ(ꢇ ꢃꢆꢙꢗꢇꢊ$
8(-ꢈ 9ꢊꢑꢊꢇ ꢋꢉꢘ(ꢇ ꢃꢆꢙꢗꢇꢊ$
8(-ꢈ 9ꢊꢑꢊꢇ ꢋꢉꢘ(ꢇ ꢃꢆꢙꢗꢇꢊ$
ꢓ
1
<
6
ꢄ(ꢛꢊ'ꢘ
ꢄ(ꢛꢊ'ꢘ
7ꢞꢉꢊ
7ꢞꢉꢊ
ꢕꢕ1ꢀ
ꢕꢕ1<
ꢄ(ꢛꢊ'ꢘ
7ꢞꢉꢊ
ꢕꢕꢓꢀ
2!ꢘꢊꢛꢉꢆꢇ ;ꢊ'ꢘꢞꢛꢊ$
ꢜ#7ꢎꢌ J C9ꢞꢝD
ꢃꢊꢊ Table 10
Table 11. 8085 CPU Maskable Interrupt Request Inputs and their Features
Direct Interrupts
ꢗꢛ(ꢞꢛ(ꢘ(Iꢆꢘ(ꢞꢉ %'ꢈꢊꢙꢊ ꢉꢞ ꢇꢞꢉ-ꢊꢛ ꢆꢗꢗꢇ(ꢊ% ꢘꢞ ꢘꢈꢆꢘ ꢗꢆꢛꢘ('ꢅꢇꢆꢛ
(ꢉꢘꢊꢛꢛꢅꢗꢘꢒ ꢀꢞꢉ%ꢊEꢅꢊꢉꢘꢇ&" (ꢘ (% ꢗꢞ%%(ꢚꢇꢊ ꢘꢈꢆꢘ ꢆꢉ ꢍꢃꢎ 6ꢒ6
(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ 'ꢞꢅꢇ$ C(ꢉꢘꢊꢛꢛꢅꢗꢘD ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ
ꢛꢞꢅꢘ(ꢉꢊ +ꢞꢛ ꢘꢈꢊ ꢈ(-ꢈꢊꢛ ꢗꢛ(ꢞꢛ(ꢘ& ꢍꢃꢎ >ꢒ6 (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘꢒ
ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢘꢈꢊ ꢅ%ꢊꢛ ꢙꢅ%ꢘ -ꢅꢆꢛ$ ꢆ-ꢆ(ꢉ%ꢘ ꢘꢈ(% ꢗꢈꢊꢉꢞꢙꢊꢉꢞꢉ
(ꢉ ꢈ(%.ꢈꢊꢛ +(ꢛꢙꢝꢆꢛꢊꢒ
ꢎꢈꢊ =ꢕ=6 ꢀ,ꢋ (ꢉꢗꢅꢘ% ꢍꢃꢎ >ꢒ6" ꢍꢃꢎ /ꢒ6" ꢆꢉ$ ꢍꢃꢎ 6ꢒ6 ꢆꢛꢊ
Cꢄ(ꢛꢊ'ꢘ #ꢉꢘꢊꢛꢛꢅꢗꢘD ꢛꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘ%ꢒ ꢃꢗꢊ'(+('ꢆꢇꢇ&" (+ ꢆꢉ& ꢞ+
ꢘꢈꢊ%ꢊ (ꢉꢗꢅꢘ% ꢆꢛꢊ ꢆ%%ꢊꢛꢘꢊ$" ꢘꢈꢊꢉ ꢘꢈꢊ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢅꢉꢘꢊꢛ ꢞ+
ꢘꢈꢊ ꢀ,ꢋ (%" ꢅꢗꢞꢉ 'ꢞꢙꢗꢇꢊꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ 'ꢅꢛꢛꢊꢉꢘ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ"
ꢆꢅꢘꢞꢙꢆꢘ('ꢆꢇꢇ& ꢇꢞꢆ$ꢊ$ ꢝ(ꢘꢈ
ꢆ
ꢙꢊꢙꢞꢛ& ꢇꢞ'ꢆꢘ(ꢞꢉ
ꢏꢗꢛꢊꢜ$ꢊꢘꢊꢛꢙ(ꢉꢊ$ ꢚ& ꢘꢈꢊ '(ꢛ'ꢅ(ꢘꢛ& ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ =ꢕ=6 $ꢊꢑ('ꢊꢐ"
ꢆꢉ$ ꢚꢛꢆꢉ'ꢈꢊ% ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢘꢞ ꢘꢈꢆꢘ ꢇꢞ'ꢆꢘ(ꢞꢉꢒ ꢎꢈꢊ%ꢊ
Cꢄ(ꢛꢊ'ꢘD (ꢉꢘꢊꢛꢛꢅꢗꢘ% $ꢞ ꢉꢞꢘ ꢗꢛꢞꢑ($ꢊ ꢘꢈꢊ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ
ꢝ(ꢘꢈ ꢆꢉ& %ꢞꢛꢘ ꢞ+ C#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊDꢒ 8ꢊꢉ'ꢊ"
ꢆ''ꢞꢛ$(ꢉ- ꢘꢞ Table 11" (+ ꢘꢈꢊ ꢍꢃꢎ >ꢒ6 (ꢉꢗꢅꢘ ꢝꢊꢛꢊ ꢆ%%ꢊꢛꢘꢊ$"
Table 11 ꢆꢇ%ꢞ (ꢉ$('ꢆꢘꢊ% ꢘꢈꢆꢘ ꢘꢈꢊ =ꢕ=6 ꢀ,ꢋ ꢝ(ꢇꢇ %ꢅꢗꢗꢞꢛꢘ
Cꢊ!ꢘꢊꢛꢉꢆꢇD ꢑꢊ'ꢘꢞꢛꢊ$ (ꢉꢘꢊꢛꢛꢅꢗꢘ%ꢒ
ꢎꢈꢊ ꢙꢆꢉꢉꢊꢛ ꢆꢉ$
'ꢞꢙꢙꢆꢉ$% ꢘꢈꢆꢘ ꢆꢛꢊ ꢅ%ꢊ$ (ꢉ ꢊ!ꢘꢊꢛꢉꢆꢇ ꢑꢊ'ꢘꢞꢛꢊ$ (ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢗꢛꢞ'ꢊ%%(ꢉ- ꢆꢛꢊ ($ꢊꢉꢘ('ꢆꢇ ꢘꢞ ꢘꢈꢆꢘ ꢗꢛꢊ%ꢊꢉꢘꢊ$ +ꢞꢛ ꢘꢈꢊ =ꢕ=ꢕ
ꢀ,ꢋ ꢏ%ꢊꢊ Section C.6.1.2ꢐꢒ
ꢘꢈꢊ ꢑꢆꢇꢅꢊ Cꢕꢕ1ꢀ D ꢝꢞꢅꢇ$ ꢚꢊ ꢇꢞꢆ$ꢊ$ (ꢉꢘꢞ ꢘꢈꢊ ꢗꢛꢞ-ꢛꢆꢙ
ꢔ/
Figure 10 ꢆꢉ$ Figure 11 ꢗꢛꢊ%ꢊꢉꢘ ꢘꢝꢞ $(++ꢊꢛꢊꢉꢘ
ꢆꢗꢗꢛꢞꢆ'ꢈꢊ% ꢘꢈꢆꢘ 'ꢆꢉ ꢚꢊ ꢅ%ꢊ$ ꢘꢞ (ꢉꢘꢊꢛ+ꢆ'ꢊ ꢘꢈꢊ 5ꢍ==ꢀ/=ꢔ
ꢄꢋꢌꢍꢎ ꢘꢞ ꢘꢈꢊ =ꢕ=6 ꢀ,ꢋꢒ
'ꢞꢅꢉꢘꢊꢛ ꢞ+ ꢘꢈꢊ ꢀ,ꢋ" ꢆꢉ$ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢝꢞꢅꢇ$ ꢚꢛꢆꢉ'ꢈ ꢘꢞ
ꢘꢈꢆꢘ ꢇꢞ'ꢆꢘ(ꢞꢉ (ꢉ ꢙꢊꢙꢞꢛ&ꢒ ꢎꢈꢊ ꢅ%ꢊꢛ (% ꢛꢊ%ꢗꢞꢉ%(ꢚꢇꢊ ꢘꢞ (ꢉ%ꢅꢛꢊ
ꢘꢈꢆꢘ ꢘꢈꢊ 'ꢞꢛꢛꢊ'ꢘ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ ꢚꢊ-(ꢉ% ꢆꢘ ꢘꢈꢆꢘ
ꢇꢞ'ꢆꢘ(ꢞꢉ (ꢉ ꢙꢊꢙꢞꢛ&ꢒ
Figure 10 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ %'ꢈꢊꢙꢆꢘ(' ꢝꢈꢊꢛꢊ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢝ(ꢇꢇ
ꢛꢊEꢅꢊ%ꢘ ꢆ Cꢄ(ꢛꢊ'ꢘD ꢍꢃꢎ /ꢒ6 #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢘꢞ ꢘꢈꢊ =ꢕ=6 ꢀ,ꢋꢒ #ꢉ
ꢘꢈ(% 'ꢆ%ꢊ" ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢊꢛꢑ('ꢊ ꢍꢞꢅꢘ(ꢉꢊ +ꢞꢛ ꢘꢈꢊ ꢄꢋꢌꢍꢎ
ꢎꢈꢊ =ꢕ=6 ꢀ,ꢋ ꢞ++ꢊꢛ% (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛ(ꢞꢛ(ꢘ(Iꢆꢘ(ꢞꢉ" ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ %ꢊꢘ
ꢞ+ ꢁꢆ%3ꢆꢚꢇꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ%ꢒ ꢎꢈ(% ꢗꢛ(ꢞꢛ(ꢘ& (% ꢛꢊ+ꢇꢊ'ꢘꢊ$ Table 11ꢒ
#ꢘ %ꢈꢞꢅꢇ$ ꢚꢊ ꢉꢞꢘꢊ$ ꢘꢈꢆꢘ ꢘꢈꢊ%ꢊ ꢗꢛ(ꢞꢛ(ꢘ& ꢇꢊꢑꢊꢇ% ꢞꢉꢇ& ꢆꢗꢗꢇ& ꢘꢞ
Cꢗꢊꢉ$(ꢉ-D (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘꢒ ꢂꢉ'ꢊ ꢆ ꢗꢆꢛꢘ('ꢅꢇꢆꢛ (ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢈꢆ% Cꢇꢊ+ꢘ ꢘꢈꢊ EꢅꢊꢅꢊD ꢆꢉ$ (% ꢚꢊ(ꢉ- %ꢊꢛꢑ('ꢊ$ ꢚ& ꢘꢈꢊ ꢀ,ꢋ" ꢘꢈ(%
ꢙꢅ%ꢘ ꢚꢊ-(ꢉ ꢆꢘ ꢕꢕ1< (ꢉ %&%ꢘꢊꢙ ꢙꢊꢙꢞꢛ&ꢒ ꢎꢈ(% (% ꢆ ꢑꢊꢛ&
ꢔ/
%(ꢙꢗꢇꢊ (ꢉꢘꢊꢛ+ꢆ'ꢊ ꢘꢊ'ꢈꢉ(Eꢅꢊ" ꢚꢊ'ꢆꢅ%ꢊ ꢘꢈꢊꢛꢊ (% ꢉꢞ C#ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊD %(-ꢉꢆꢇ ꢘꢞ ꢛꢞꢅꢘꢊ ꢆꢉ$ (ꢉꢘꢊꢛ+ꢆ'ꢊꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
1ꢓ
XR88C681
;
''
ꢜ#7ꢎꢍ
ꢍꢃꢎ /ꢒ6
ꢌꢄꢕ ꢜ ꢌꢄ>
ꢄꢕ ꢜ ꢄ>
ꢌꢕ ꢜ ꢌ1
ꢄ
ꢀ
)
ꢌ92
ꢌ> ꢜ ꢌ<
74LS373
ꢌ$$ꢛꢊ%% ꢄꢊ'ꢞ$(ꢉ-
9ꢞ-('
ꢌꢔ6 ꢜ ꢌ=
ꢜꢀꢃ
ꢜ#ꢂꢍ
ꢜ#ꢂ.ꢁ
ꢜꢍꢄ
ꢜꢍꢄ
ꢜꢁ2ꢁꢍ
ꢜBꢍ
ꢜBꢍ
ꢜ#ꢂB
XR88C681
ꢜꢁ2ꢁB
8085 CPU
Figure 10. The XR88C681/8085 CPU Interface for Direct Interrupt Processing
(Interrupt Service Routine is located at 0034 in System Memory)
16
Figure 11 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ %'ꢈꢊꢙꢆꢘ(' ꢝꢈꢊꢛꢊ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢝ(ꢇꢇ ꢛꢊEꢅꢊ%ꢘ ꢆ C2!ꢘꢊꢛꢉꢆꢇꢜ;ꢊ'ꢘꢞꢛꢊ$D #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢘꢞ ꢘꢈꢊ =ꢕ=6 ꢀ,ꢋꢒ #ꢉ ꢘꢈ(%
'ꢆ%ꢊ" ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢊꢛꢑ('ꢊ ꢍꢞꢅꢘ(ꢉꢊ +ꢞꢛ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢙꢅ%ꢘ ꢚꢊ-(ꢉ ꢆꢘ ꢕꢕꢓꢕ (ꢉ %&%ꢘꢊꢙ ꢙꢊꢙꢞꢛ&ꢒ
ꢔ/
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
11
XR88C681
;''
U1
U4
ꢋ6
#7ꢎꢍ
ꢜ#7ꢎꢍ
ꢋ/
;''
ꢜ#7ꢎꢌ
ꢋ1
8085 CPU
ꢜꢂ2ꢔ ꢜꢂ2ꢓ
ꢄꢕ
ꢄꢔ
ꢄꢓ
ꢄ1
ꢄ<
ꢄ6
ꢄ/
ꢄ>
ꢄꢂꢕ
ꢌꢄꢕ
ꢌꢄꢔ
ꢌꢄꢓ
ꢌꢄ1
ꢌꢄ<
ꢌꢄ6
ꢌꢄ/
ꢌꢄ>
ꢄ#ꢕ
ꢄ#ꢔ
ꢄ#ꢓ
ꢄ#1
ꢄ#<
ꢄ#6
ꢄ#/
ꢄꢂꢔ
ꢄꢂꢓ
ꢄꢂ1
ꢄꢂ<
ꢄꢂ6
ꢄꢂ/
XR88C681
ꢄ#>
ꢄꢂ>
SN74LS244
ꢌꢕ
ꢔ)
ꢓ)
1)
ꢔꢄ
ꢓꢄ
1ꢄ
<ꢄ
6ꢄ
/ꢄ
>ꢄ
=ꢄ
ꢀ
ꢌꢔ
ꢌꢓ
ꢌ1
<)
6)
/)
ꢌ<
ꢌ6
ꢌ/
ꢌ>
>)
=)
ꢌ92
74LS373
Figure 11. The XR88C681/8085 CPU Interface for Vectored Interrupt Processing (In-
terrupt Service Routine is located at 0020 in system memory)
16
C.6.1.4 68HC11 Microcontroller
ꢁꢞꢘꢞꢛꢞꢇꢆ ꢙꢆꢉꢅ+ꢆ'ꢘꢅꢛꢊ% ꢆ +ꢆꢙ(ꢇ& ꢞ+ ꢙ('ꢛꢞ'ꢞꢉꢘꢛꢞꢇꢇꢊꢛ%" ꢛꢊ+ꢊꢛꢛꢊ$ ꢘꢞ ꢆ% ꢘꢈꢊ ꢁꢀ/=8ꢀꢔꢔ ꢙ('ꢛꢞ'ꢞꢉꢘꢛꢞꢇꢇꢊꢛ%ꢒ ꢎꢈ(% +ꢆꢙ(ꢇ& ꢞ+
ꢙ('ꢛꢞ'ꢞꢉꢘꢛꢞꢇꢇꢊꢛ% ꢞ++ꢊꢛ% %ꢞꢙꢊ ꢞ+ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- ꢆꢙꢊꢉ(ꢘ(ꢊ%4
ꢁ 6 ꢁꢅꢇꢘ(ꢜ ꢅꢉ'ꢘ(ꢞꢉ ,ꢆꢛꢆꢇꢇꢊꢇ ,ꢞꢛꢘ%
ꢁ ꢍꢂꢁ ꢞꢛ 2,ꢍꢂꢁ
ꢁ ꢍꢌꢁ
ꢁ ꢌ.ꢄ ꢀꢞꢉꢑꢊꢛꢘꢊꢛ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
1<
XR88C681
Figure 12 ꢗꢛꢊ%ꢊꢉꢘ% ꢘꢈꢊ ꢚꢇꢞ'3 $(ꢆ-ꢛꢆꢙ ꢞ+ ꢘꢈꢊ ꢁꢀ/=8ꢀꢔꢔ• ꢀꢒ
ꢁꢂꢄꢌ
ꢁꢂꢄ*
5ꢎꢌ9 25ꢎꢌ9 2
ꢜ#ꢍ) ꢜ5#ꢍ) ꢜꢍ2ꢃ2ꢎ
ꢂ%'(ꢇꢇꢆꢘꢞꢛ
#ꢉꢘꢊꢛꢛꢅꢗꢘ
9ꢞ-('
ꢁꢞ$ꢊ ꢀꢞꢉꢘꢛꢞꢇ
ꢀꢇꢞ'3 9ꢞ-('
ꢍꢌꢁ ꢓ6/ *&ꢘꢊ%
ꢀ,ꢋ ꢀꢞꢛꢊ
;ꢍ8
;ꢍ9
ꢎ(ꢙꢊꢛ
ꢃ&%ꢘꢊꢙ
*ꢅ% 2!ꢗꢆꢉ%(ꢞꢉ
ꢌ$$ꢛꢊ%%
ꢌ$$ꢛꢊ%%.ꢄꢆꢘꢆ
ꢃ,#
ꢃꢀ#
ꢌ.ꢄ ꢀꢞꢉꢑꢊꢛꢘꢊꢛ
ꢃꢘꢛꢞꢚꢊ ꢆꢉ$ 8ꢆꢉ$%ꢈꢆ3ꢊ ,ꢆꢛꢆꢇꢇꢊꢇ #.ꢂ
=
ꢀꢞꢉꢘꢛꢞꢇ
ꢀꢞꢉꢘꢛꢞꢇ
,ꢞꢛꢘ ꢄ
,ꢞꢛꢘ ꢌ
,ꢞꢛꢘ ꢀ
,ꢞꢛꢘ *
,ꢞꢛꢘ 2
Figure 12. Block Diagram of the MC68HC11 Microcontroller
ꢎꢈꢊ /=8ꢀꢔꢔ 'ꢆꢉ ꢚꢊ 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢆ Cꢃ(ꢉ-ꢇꢊ
ꢀꢈ(ꢗD ꢁꢞ$ꢊ ꢞꢛ (ꢉ ꢆꢉ C2!ꢗꢆꢉ$ꢊ$ ꢁꢅꢇꢘ(ꢗꢇꢊ!ꢊ$ *ꢅ%D ꢙꢞ$ꢊꢒ #+
ꢆ $ꢊꢑ('ꢊ (% 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈꢊ Cꢃ(ꢉ-ꢇꢊ ꢀꢈ(ꢗD
ꢙꢞ$ꢊ" ꢘꢈꢊ ꢊꢉꢘ(ꢛꢊ /<: ꢚ&ꢘꢊ% ꢞ+ ꢌ$$ꢛꢊ%% %ꢗꢆ'ꢊ (% (ꢉꢘꢊꢛꢉꢆꢇ ꢘꢞ
ꢘꢈꢊ • ꢀ #ꢀꢒ Please note that this does not mean that there
is 64K bytes of memory, or other addressable portions
within the deviceꢒ ꢌ /=8ꢀꢔꢔ ꢁꢀꢋ 'ꢞꢉ+(-ꢅꢛꢊ$ +ꢞꢛ Cꢃ(ꢉ-ꢇꢊ
ꢀꢈ(ꢗD ꢙꢞ$ꢊ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ 'ꢆꢉꢉꢞꢘ ꢆ$$ꢛꢊ%% ꢆꢉ& 'ꢞꢙꢗꢞꢉꢊꢉꢘ%
ꢊ!ꢘꢊꢛꢉꢆꢇ ꢘꢞ ꢘꢈꢊ ꢁꢀꢋꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" (+ ꢆ ꢅ%ꢊꢛ $ꢊ%(ꢛꢊ$ ꢘꢞ
(ꢉꢘꢊꢛ+ꢆ'ꢊ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢘꢞ ꢘꢈ(% • ꢀ" ꢘꢈꢊꢉ ꢘꢈꢊ • ꢀ ꢙꢅ%ꢘ ꢞꢗꢊꢛꢆꢘꢊ
(ꢉ ꢘꢈꢊ C2!ꢗꢆꢉ$ꢊ$ꢜꢁꢅꢇꢘ(ꢗꢇꢊ!ꢊ$D ꢙꢞ$ꢊꢒ ꢎꢈꢊ ꢁꢀ/=8ꢀꢔꢔ (%
'ꢞꢉ+(-ꢅꢛꢊ$ (ꢉꢘꢞ ꢘꢈꢊ 2!ꢗꢆꢉ$ꢊ$ ꢁꢅꢇꢘ(ꢗꢇꢊ!ꢊ$ ꢙꢞ$ꢊ ꢚ& ꢘ&(ꢉ-
ꢚꢞꢘꢈ ꢘꢈꢊ ꢁꢂꢄꢌ ꢆꢉ$ ꢁꢂꢄ* ꢗ(ꢉ ꢘꢞ ;''" ꢆꢉ$ ꢘꢈꢊꢉ ꢛꢊ%ꢊꢘꢘ(ꢉ-
ꢘꢈꢊ $ꢊꢑ('ꢊꢒ
ꢎꢈꢊ ꢁꢀ/=8ꢀꢔꢔ 'ꢞꢉ%(%ꢘ% ꢞ+ 6 $(++ꢊꢛꢊꢉꢘ ꢙꢅꢇꢘ(ꢜ+ꢅꢉ'ꢘ(ꢞꢉ
ꢗꢆꢛꢆꢇꢇꢊꢇ ꢗꢞꢛꢘ%ꢒ 2ꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ ꢗꢞꢛꢘ% ꢆꢛꢊ ꢚꢛ(ꢊ+ꢇ& $(%'ꢅ%%ꢊ$ꢒ
Port A
,ꢞꢛꢘ ꢌ 'ꢞꢉ%(%ꢘ% ꢞ+ 1 (ꢉꢗꢅꢘ ꢗ(ꢉ%" < ꢞꢅꢘꢗꢅꢘ ꢗ(ꢉ% ꢆꢉ$ ꢔ
ꢚ(ꢜ$(ꢛꢊ'ꢘ(ꢞꢉꢆꢇ ꢗ(ꢉꢒ ꢎꢈ(% ꢗꢞꢛꢘ (% ꢅ%ꢊ$ ꢘꢞ %ꢅꢗꢗꢞꢛꢘ ꢘꢈꢊ ꢎ(ꢙꢊꢛ
ꢃ&%ꢘꢊꢙꢒ ꢂꢉꢊ ꢞ+ ꢘꢈꢊ (ꢉꢗꢅꢘ ꢗ(ꢉ% 'ꢆꢉ ꢚꢊ ꢅ%ꢊ$ +ꢞꢛ ꢘꢈꢊ ,ꢅꢇ%ꢊ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
16
XR88C681
ꢌ''ꢅꢙꢅꢇꢆꢘꢞꢛꢒ ꢎꢈꢛꢊꢊ ꢞ+ ꢘꢈꢊ (ꢉꢗꢅꢘ ꢗ(ꢉ% %ꢅꢗꢗꢞꢛꢘ (ꢉꢗꢅꢘ
'ꢆꢗꢘꢅꢛꢊ +ꢅꢉ'ꢘ(ꢞꢉ%L ꢆꢉ$ +ꢞꢅꢛ ꢞ+ ꢘꢈꢊ ꢞꢅꢘꢗꢅꢘ ꢗ(ꢉ% %ꢅꢗꢗꢞꢛꢘ
ꢞꢅꢘꢗꢅꢘ 'ꢞꢙꢗꢆꢛꢊ +ꢅꢉ'ꢘ(ꢞꢉ%ꢒ
IRQ
ꢎꢈ(% (% ꢘꢈꢊ Cꢙꢆ%3ꢆꢚꢇꢊD (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘꢒ #+ ꢘꢈ(% (ꢉꢗꢅꢘ
(% ꢆ%%ꢊꢛꢘꢊ$ ꢏꢊꢒ-ꢒ" ꢘꢞ--ꢇꢊ$ CꢇꢞꢝDꢐ" ꢘꢈꢊꢉ ꢘꢈꢊ /=8ꢀꢔꢔ • ꢀ ꢝ(ꢇꢇ
ꢚꢛꢆꢉ'ꢈ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢘꢞ ꢓ" 1 (ꢉ %&%ꢘꢊꢙ ꢙꢊꢙꢞꢛ&
ꢏꢞꢉꢜ'ꢈ(ꢗ ꢍꢂꢁꢐꢒ ꢎꢈꢊ ꢅ%ꢊꢛ (% ꢛꢊ%ꢗꢞꢉ%(ꢚꢇꢊ +ꢞꢛ (ꢉ%ꢅꢛ(ꢉ- ꢘꢈꢆꢘ
ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ ꢛꢊ%($ꢊ% ꢆꢘ ꢘꢈ(%
ꢇꢞ'ꢆꢘ(ꢞꢉ (ꢉ ꢙꢊꢙꢞꢛ&ꢒ
Port B
,ꢞꢛꢘ * 'ꢞꢉ%(%ꢘ% ꢞ+ = ꢞꢅꢘꢗꢅꢘ ꢗ(ꢉ%ꢒ #+ ꢘꢈꢊ /=8ꢀꢔꢔ • ꢀ (%
ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ %(ꢉ-ꢇꢊ 'ꢈ(ꢗ ꢙꢞ$ꢊ" ꢘꢈ(% ꢗꢞꢛꢘ +ꢅꢉ'ꢘ(ꢞꢉ% ꢆ% ꢆ
-ꢊꢉꢊꢛꢆꢇ ꢗꢅꢛꢗꢞ%ꢊ ꢞꢅꢘꢗꢅꢘ ꢗꢞꢛꢘꢒ 8ꢞꢝꢊꢑꢊꢛ" (+ ꢘꢈꢊ /=8ꢀꢔꢔ (%
ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ ꢊ!ꢗꢆꢉ$ꢊ$ꢜꢙꢅꢇꢘ(ꢗꢇꢊ!ꢊ$ ꢙꢞ$ꢊ" ꢘꢈꢊꢉ ꢘꢈ(%
ꢗꢞꢛꢘ ꢝ(ꢇꢇ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢅꢗꢗꢊꢛ ꢆ$$ꢛꢊ%% ꢚ&ꢘꢊ +ꢞꢛ
ꢙꢊꢙꢞꢛ&.ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢏꢌ= ꢜ ꢌꢔ6ꢐꢒ
AS/STRA
ꢌꢃ ꢞꢛ Cꢌ$$ꢛꢊ%% ꢃꢘꢛꢞꢚꢊD 'ꢆꢉ ꢚꢊ ꢅ%ꢊ$ ꢘꢞ $ꢊꢙꢅꢇꢘ(ꢗꢇꢊ! ꢘꢈꢊ
ꢆ$$ꢛꢊ%%.$ꢆꢘꢆ ꢚꢅ% ꢞ+ ,ꢞꢛꢘ ꢀꢒ ꢎꢈ(% ꢗ(ꢉ (% ꢆꢘ ꢆ ꢇꢞ-(' Cꢈ(-ꢈD
$ꢅꢛ(ꢉ- ꢘꢈꢊ +(ꢛ%ꢘ ꢈꢆꢇ+ ꢞ+ ꢆ ꢙꢊꢙꢞꢛ& '&'ꢇꢊL ꢆꢉ$ ꢆꢘ ꢆ ꢇꢞ-(' CꢇꢞꢝD
$ꢅꢛ(ꢉ- ꢘꢈꢊ %ꢊ'ꢞꢉ$ ꢈꢆꢇ+ ꢞ+ ꢆ ꢙꢊꢙꢞꢛ& '&'ꢇꢊꢒ
Port C
,ꢞꢛꢘ ꢀ 'ꢞꢉ%(%ꢘ% ꢞ+ = ꢚ(ꢜ$(ꢛꢊ'ꢘ(ꢞꢉꢆꢇ ꢗ(ꢉ%ꢒ Bꢈꢊꢉ ꢘꢈꢊ /=8ꢀꢔꢔ
(% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ %(ꢉ-ꢇꢊꢜ'ꢈ(ꢗ ꢙꢞ$ꢊ" ꢘꢈ(% ꢗꢞꢛꢘ +ꢅꢉ'ꢘ(ꢞꢉ% ꢆ%
ꢆ -ꢊꢉꢊꢛꢆꢇ ꢗꢅꢛꢗꢞ%ꢊ ꢚ(ꢜ$(ꢛꢊ'ꢘ(ꢞꢉꢆꢇ ꢗꢞꢛꢘꢒ 8ꢞꢝꢊꢑꢊꢛ" (+ ꢘꢈꢊ
/=8ꢀꢔꢔ (% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ ꢊ!ꢗꢆꢉ$ꢊ$ꢜꢙꢅꢇꢘ(ꢗꢇꢊ!ꢊ$ ꢙꢞ$ꢊ
ꢘꢈꢊꢉ ꢘꢈ(% ꢗꢞꢛꢘ ꢝ(ꢇꢇ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢙꢅꢇꢘ(ꢗꢇꢊ!ꢊ$ ꢆ$$ꢛꢊ%%.$ꢆꢘꢆ
ꢚꢅ% ꢏꢌꢄꢕ ꢜ ꢌꢄ>ꢐꢒ ꢃꢗꢊ'(+('ꢆꢇꢇ&" $ꢅꢛ(ꢉ- ꢘꢈꢊ +(ꢛ%ꢘ ꢈꢆꢇ+ ꢞ+ ꢆ
ꢙꢊꢙꢞꢛ& '&'ꢇꢊ" ꢘꢈ(% ꢗꢞꢛꢘ ꢝ(ꢇꢇ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢇꢞꢝꢊꢛ ꢆ$$ꢛꢊ%%
ꢚ&ꢘꢊ ꢏ,ꢞꢛꢘ * (% ꢘꢈꢊ ꢅꢗꢗꢊꢛ ꢆ$$ꢛꢊ%% ꢚ&ꢘꢊꢐ +ꢞꢛ ꢆ$$ꢛꢊ%%(ꢉ-
ꢙꢊꢙꢞꢛ& $ꢊꢑ('ꢊ% ꢆꢉ$ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ 'ꢞꢙꢗꢞꢉꢊꢉꢘ%ꢒ ꢄꢅꢛ(ꢉ- ꢘꢈꢊ
%ꢊ'ꢞꢉ$ ꢈꢆꢇ+ ꢞ+ ꢘꢈꢊ ꢙꢊꢙꢞꢛ& '&'ꢇꢊ" ꢘꢈ(% ꢗꢞꢛꢘ ꢝ(ꢇꢇ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ%
#+ ꢘꢈꢊ /=8ꢀꢔꢔ (% (ꢉꢘꢊꢉ$ꢊ$ ꢘꢞ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈꢊ
ꢊ!ꢗꢆꢉ$ꢊ$ꢜꢙꢅꢇꢘ(ꢗꢇꢊ!ꢊ$ ꢙꢞ$ꢊ ꢆꢉ$ (ꢉꢘꢊꢛ+ꢆ'ꢊ ꢘꢞ ꢙꢞꢛꢊ ꢘꢈꢆꢉ
ꢓ6/ ꢚ&ꢘꢊ% ꢞ+ ꢆ$$ꢛꢊ%%ꢆꢚꢇꢊ ꢙꢊꢙꢞꢛ& %ꢗꢆ'ꢊ" ꢘꢈꢊꢉ ꢚꢞꢘꢈ ,ꢞꢛꢘ%
* ꢆꢉ$ ꢀ ꢆꢛꢊ ꢛꢊEꢅ(ꢛꢊ$ ꢆ% %ꢈꢞꢝꢉ (ꢉ Figure 13ꢒ Figure 13
ꢆꢇ%ꢞ (ꢇꢇꢅ%ꢘꢛꢆꢘꢊ% ꢈꢞꢝ ꢘꢈꢊ 5ꢍ==ꢀ/=ꢔ ꢄꢋꢌꢍꢎ 'ꢞꢅꢇ$ ꢚꢊ
'ꢞꢉꢉꢊ'ꢘꢊ$ ꢘꢞ ꢘꢈꢊ /=8ꢀꢔꢔ • ꢀ +ꢞꢛ (ꢉꢘꢊꢛꢛꢅꢗꢘ $ꢛ(ꢑꢊꢉ
ꢞꢗꢊꢛꢆꢘ(ꢞꢉꢒ #+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢛꢊEꢅꢊ%ꢘ% ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ" (ꢘ% ꢆ'ꢘ(ꢑꢊ
ꢇꢞꢝ ꢜ#7ꢎꢍ ꢗ(ꢉ ꢝ(ꢇꢇ ꢚꢊ ꢆ%%ꢊꢛꢘꢊ$ ꢏꢘꢞ--ꢇꢊ ꢇꢞꢝꢐ" ꢝꢈ('ꢈ ꢝ(ꢇꢇ" (ꢉ
ꢘꢅꢛꢉ" 'ꢆꢅ%ꢊ ꢘꢈꢊ ꢜ#ꢍ) ꢗ(ꢉ ꢞ+ ꢘꢈꢊ ꢀ,ꢋ ꢘꢞ ꢚꢊ ꢆ%%ꢊꢛꢘꢊ$ꢒ Bꢈꢊꢉ
ꢘꢈ(% ꢞ''ꢅꢛ% ꢘꢈꢊ • ꢀ ꢝ(ꢇꢇ 'ꢞꢉꢘ(ꢉꢅꢊ ꢊ!ꢊ'ꢅꢘ(ꢉ- (ꢘ% 'ꢅꢛꢛꢊꢉꢘ
(ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉꢒ ꢌ+ꢘꢊꢛ 'ꢞꢙꢗꢇꢊꢘ(ꢞꢉ ꢞ+ ꢘꢈ(% (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ" ꢗꢛꢞ-ꢛꢆꢙ
'ꢞꢉꢘꢛꢞꢇ ꢝ(ꢇꢇ %ꢈ(+ꢘ ꢘꢞ ꢇꢞ'ꢆꢘ(ꢞꢉ ꢓ" 1 (ꢉ %&%ꢘꢊꢙ
ꢙꢊꢙꢞꢛ&ꢒ ꢎꢈꢊ ꢅ%ꢊꢛ (% ꢛꢊ%ꢗꢞꢉ%(ꢚꢇꢊ ꢘꢞ (ꢉ%ꢅꢛꢊ ꢘꢈꢆꢘ ꢘꢈꢊ
ꢄꢋꢌꢍꢎH% (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ ꢛꢊ%($ꢊ% ꢆꢘ ꢘꢈ(% ꢇꢞ'ꢆꢘ(ꢞꢉ
ꢘꢈꢊ ꢚ(ꢜ$(ꢛꢊ'ꢘ(ꢞꢉꢆꢇ $ꢆꢘꢆ ꢚꢅ%ꢒ
ꢎꢈ(% ꢗꢞꢛꢘ 'ꢆꢉ ꢚꢊ
$ꢊꢙꢅꢇꢘ(ꢗꢇꢊ!ꢊ$ ꢑ(ꢆ ꢘꢈꢊ ꢅ%ꢊ ꢞ+ ꢘꢈꢊ ꢌꢃ ꢏꢌ$$ꢛꢊ%% ꢃꢘꢛꢞꢚꢊꢐ ꢗ(ꢉ
ꢆꢉ$ ꢆ ><9ꢃ1>1 ꢇꢆꢘ'ꢈ $ꢊꢑ('ꢊꢒ
Port D
,ꢞꢛꢘ ꢄ 'ꢞꢉ%(%ꢘ% ꢞ+ = ꢚ(ꢜ$(ꢛꢊ'ꢘ(ꢞꢉꢆꢇ ꢗ(ꢉ%ꢒ 8ꢞꢝꢊꢑꢊꢛ" ꢘꢈ(% ꢗꢞꢛꢘ
'ꢆꢉ ꢚꢊ 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ %ꢅꢗꢗꢞꢛꢘ ꢘꢈꢊ ꢞꢉꢜ'ꢈ(ꢗ ꢃꢊꢛ(ꢆꢇ ,ꢊꢛ(ꢗꢈꢊꢛꢆꢇ
#ꢉꢘꢊꢛ+ꢆ'ꢊ ꢏꢃ,#ꢐ" ꢆꢉ$ ꢃꢊꢛ(ꢆꢇ ꢀꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉ% #ꢉꢘꢊꢛ+ꢆ'ꢊ
ꢏꢃꢀ#ꢐꢒ
(ꢉ ꢙꢊꢙꢞꢛ&ꢒ
ꢎꢈꢊ • ꢀ ꢝ(ꢇꢇ ꢉꢞꢘ (%%ꢅꢊ ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢆ'3ꢉꢞꢝꢇꢊ$-ꢊ %(-ꢉꢆꢇ ꢘꢞ ꢘꢈꢊ ꢄꢋꢌꢍꢎꢒ #ꢉ%ꢘꢊꢆ$" ꢘꢈꢊ • ꢀ ꢝ(ꢇꢇ
Mꢅ%ꢘ ꢗꢛꢞ'ꢊ%%ꢊ% ꢘꢈꢛꢞꢅ-ꢈ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊꢒ
ꢂꢉ'ꢊ ꢘꢈꢊ • ꢀ ꢈꢆ% ꢊꢇ(ꢙ(ꢉꢆꢘꢊ$ ꢘꢈꢊ 'ꢆꢅ%ꢊꢏ%ꢐ ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎH%
(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ" ꢘꢈꢊ ꢜ#7ꢎꢍ ꢗ(ꢉ ꢝ(ꢇꢇ ꢚꢊ ꢉꢊ-ꢆꢘꢊ$ ꢆꢉ$ ꢘꢈꢊ • ꢀ
ꢝ(ꢇꢇ ꢛꢊꢘꢅꢛꢉ +ꢛꢞꢙ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢊꢛꢑ('ꢊ ꢍꢞꢅꢘ(ꢉꢊ ꢆꢉ$ ꢛꢊ%ꢅꢙꢊ
ꢉꢞꢛꢙꢆꢇ ꢗꢛꢞ'ꢊ%%(ꢉ-ꢒ
Port E
,ꢞꢛꢘ 2 'ꢞꢉ%(%ꢘ% ꢞ+ ꢊ(ꢘꢈꢊꢛ < ꢞꢛ = (ꢉꢗꢅꢘ% ꢏ$ꢊꢗꢊꢉ$(ꢉ- ꢅꢗꢞꢉ ꢘꢈꢊ
ꢗꢆ'3ꢆ-(ꢉ- ꢞꢗꢘ(ꢞꢉꢐꢒ ꢎꢈ(% ꢗꢞꢛꢘ 'ꢆꢉ ꢚꢊ 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ
ꢆ% ꢆ -ꢊꢉꢊꢛꢆꢇ ꢗꢅꢛꢗꢞ%ꢊ (ꢉꢗꢅꢘ ꢞꢛ ꢆ% ꢘꢈꢊ (ꢉꢗꢅꢘ% ꢘꢞ ꢘꢈꢊ ꢞꢉꢜ'ꢈ(ꢗ
ꢌ.ꢄ 'ꢞꢉꢑꢊꢛꢘꢊꢛꢒ
ꢂꢉꢊ ꢙꢞꢛꢊ ꢗꢞ(ꢉꢘ %ꢈꢞꢅꢇ$ ꢚꢊ ꢙꢊꢉꢘ(ꢞꢉꢊ$ ꢆꢚꢞꢅꢘ Figure 13ꢒ
ꢎꢈꢊ -ꢇꢅꢊꢜꢇꢞ-(' '(ꢛ'ꢅ(ꢘꢛ& ꢛꢊEꢅ(ꢛꢊ$ ꢘꢞ -ꢊꢉꢊꢛꢆꢘꢊ ꢘꢈꢊ ꢜBꢍ"
ꢜꢍꢄ" ꢆꢉ$ ꢘꢈꢊ ꢍ2ꢃ2ꢎ %(-ꢉꢆꢇ% +ꢞꢛ ꢘꢈꢊ ꢄꢋꢌꢍꢎ" +ꢛꢞꢙ ꢘꢈꢊ
ꢜꢍ.B" ꢜꢍ2ꢃ2ꢎ" ꢆꢉ$ 2 'ꢇꢞ'3 ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ Figure 2ꢒ ꢎꢈ(%
'(ꢛ'ꢅ(ꢘꢛ& ꢈꢆ% ꢆꢇ%ꢞ ꢚꢊꢊꢉ (ꢉ'ꢇꢅ$ꢊ$ (ꢉ Figure 14ꢒ
ꢎꢈꢊꢛꢊ ꢆꢛꢊ ꢉꢅꢙꢊꢛꢞꢅ% ꢞꢘꢈꢊꢛ ꢗ(ꢉ% ꢘꢈꢆꢘ ꢆꢛꢊ ꢗꢊꢛꢘ(ꢉꢊꢉꢘ +ꢞꢛ
(ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢞ ꢘꢈꢊ 5ꢍ==ꢀ/=ꢔ ꢄꢋꢌꢍꢎ $ꢊꢑ('ꢊꢒ ꢃꢞꢙꢊ ꢞ+
ꢘꢈꢊ%ꢊ ꢗ(ꢉ% ꢆꢛꢊ $(%'ꢅ%%ꢊ$ ꢈꢊꢛꢊꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
1/
XR88C681
ꢘꢞ ꢞꢘꢈꢊꢛ #ꢀ%
6;
2
ꢜꢍ.B
ꢁꢂꢄꢌ
ꢁꢂꢄ*
ꢌ$$ꢛꢊ%%
ꢄꢊ'ꢞ$ꢊꢛ
ꢌ= ꢜ ꢌꢔ6
ꢜꢀꢃ
ꢜꢍꢄ
ꢜBꢍ
ꢜ#ꢍ)
ꢜ#7ꢎꢍ
ꢌ< ꢜ ꢌ>
0
ꢄ
ꢌꢃ
)
ꢌꢕ ꢜ ꢌ1
ꢌꢕ ꢜ ꢌ1
74HC373
ꢄꢕ ꢜ ꢄ>
ꢌꢄꢕ ꢜ ꢌꢄ>
68HC11
XR88C681
Figure 13. XR88C681/MC68HC11 Microcontroller Interfacing Approach
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
1>
XR88C681
ꢜꢍ.B
ꢜBꢍ
2 'ꢇꢞ'3
ꢜꢍꢄ
ꢜꢍ2ꢃ2ꢎ
ꢍ2ꢃ2ꢎ
Figure 14. Glue Logic Circuitry Required to Interface the MC68HC11• C to the XR88C681 DUART
C.6.1.5 Z-80 CPU
ꢚꢊ %ꢊꢛꢑꢊ$ꢒ Bꢈꢊꢉ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢈꢆ% ꢛꢊ'ꢊ(ꢑꢊ$ ꢏꢞꢛ $ꢊꢘꢊ'ꢘꢊ$ꢐ
ꢘꢈꢊ #ꢌꢀ: %(-ꢉꢆꢇ" (ꢘ ꢝ(ꢇꢇ" (ꢉ ꢛꢊ%ꢗꢞꢉ%ꢊ" ꢗꢇꢆ'ꢊ ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+
ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ ꢍꢊ-(%ꢘꢊꢛ ꢏ#;ꢍꢐ ꢞꢉ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ%ꢒ ꢎꢈꢊ
ꢀ,ꢋ ꢝ(ꢇꢇ ꢛꢊꢆ$ ꢘꢈ(% C(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢑꢊ'ꢘꢞꢛD (ꢉ+ꢞꢛꢙꢆꢘ(ꢞꢉL ꢆꢉ$
$ꢊꢘꢊꢛꢙ(ꢉꢊ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- ꢘꢝꢞ ꢘꢈ(ꢉ-% ꢏꢚꢆ%ꢊ$ ꢞꢉ ꢘꢈꢊ
C(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢑꢊ'ꢘꢞꢛD (ꢉ+ꢞꢛꢙꢆꢘ(ꢞꢉꢐꢒ
ꢎꢈꢊ ?ꢜ=ꢕ ꢀ,ꢋ 'ꢆꢉ ꢚꢊ (ꢉꢘꢊꢛ+ꢆ'ꢊ$ ꢘꢞ ꢆ ꢄꢋꢌꢍꢎ ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ
ꢘꢈꢊ #ꢜꢁꢞ$ꢊ" (+ (ꢘ ꢏꢘꢈꢊ ꢀ,ꢋꢐ (% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢞ$ꢊ% ꢕ
ꢞꢛ ꢔꢒ 8ꢞꢝꢊꢑꢊꢛ" +ꢞꢛ ꢘꢈꢊ %ꢆ3ꢊ ꢞ+ Cꢗꢛꢞ'ꢊ%% ꢞꢛ 'ꢞꢉꢘ(ꢉꢅ(ꢘ&D" ꢘꢈꢊ
$ꢊꢘꢆ(ꢇ% ꢆ%%ꢞ'(ꢆꢘꢊ$ ꢝ(ꢘꢈ ꢘꢈꢊ ?ꢜ=ꢕ ꢀ,ꢋ ꢝ(ꢇꢇ ꢚꢊ ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ
Section C.6.2.1ꢒ
ꢁ ꢎꢈꢊ %ꢞꢅꢛ'ꢊ ꢞ+ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ ꢏꢊꢒ-ꢒ" ꢝꢈ('ꢈ ꢗꢊꢜ
ꢛ(ꢗꢈꢊꢛꢆꢇ ꢉꢊꢊ$% %ꢊꢛꢑ('ꢊꢐꢒ
C.6.2 Z-Mode Interrupt Servicing
ꢁ ꢎꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ ꢇꢞ'ꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢜ
ꢘ(ꢉꢊꢒ
ꢎꢈꢊ ꢄꢋꢌꢍꢎ ꢝ(ꢇꢇ ꢚꢊ (ꢉ ꢘꢈꢊ #ꢜꢁꢞ$ꢊ +ꢞꢇꢇꢞꢝ(ꢉ- ꢗꢞꢝꢊꢛ ꢅꢗ ꢞꢛ ꢆ
ꢈꢆꢛ$ꢝꢆꢛꢊ ꢛꢊ%ꢊꢘ ꢞ+ ꢘꢈꢊ #ꢀꢒ ꢎꢈꢊ ꢅ%ꢊꢛ ꢙꢅ%ꢘ (ꢉꢑꢞ3ꢊ ꢘꢈꢊ Cꢃꢊꢘ
?ꢜꢁꢞ$ꢊD 'ꢞꢙꢙꢆꢉ$ ꢏ%ꢊꢊ Table 3ꢐ" (ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ 'ꢞꢙꢙꢆꢉ$
ꢘꢈꢊ ꢄꢋꢌꢍꢎ (ꢉꢘꢞ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊꢒ #ꢉ -ꢊꢉꢊꢛꢆꢇ" ꢆ ꢀ,ꢋ
(ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢞ ꢆ ꢄꢋꢌꢍꢎ ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊ ꢝ(ꢇꢇ
+ꢅꢉ'ꢘ(ꢞꢉ ꢆ% +ꢞꢇꢇꢞꢝ% $ꢅꢛ(ꢉ- (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('(ꢉ-ꢒ
ꢌ+ꢘꢊꢛꢝꢆꢛ$%" ꢗꢛꢞ-ꢛꢆꢙꢜ'ꢞꢉꢘꢛꢞꢇ ꢝ(ꢇꢇ ꢚꢊ ꢚꢛꢆꢉ'ꢈꢊ$ ꢘꢞ ꢘꢈꢊ
ꢇꢞ'ꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊꢒ
ꢌꢉꢞꢘꢈꢊꢛ 'ꢈꢆꢛꢆ'ꢘꢊꢛ(%ꢘ(' ꢞ+ ?ꢜꢁꢞ$ꢊ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ (% ꢘꢈꢆꢘ (ꢘ
ꢆꢇꢇꢞꢝ% ꢘꢈꢊ ꢅ%ꢊꢛ ꢘꢞ ꢗꢛ(ꢞꢛ(ꢘ(Iꢊ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ% +ꢛꢞꢙ
ꢉꢅꢙꢊꢛꢞꢅ% ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ%" ꢑ(ꢆ ꢈꢆꢛ$ꢝꢆꢛꢊ ꢙꢊꢆꢉ%ꢒ 9ꢊꢘ
ꢅ% %ꢅꢗꢗꢞ%ꢊ ꢘꢈꢆꢘ ꢝꢊ ꢈꢆꢑꢊ %ꢊꢑꢊꢛꢆꢇ ꢄꢋꢌꢍꢎ $ꢊꢑ('ꢊ%L ꢆꢉ$
ꢘꢈꢆꢘ ꢊꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ $ꢊꢑ('ꢊ% ꢈꢆꢑꢊ ꢚꢊꢊꢉ 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ
ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊꢒ ꢎꢈꢊ ꢅ%ꢊꢛ 'ꢞꢅꢇ$ ꢗꢛ(ꢞꢛ(ꢘ(Iꢊ ꢘꢈꢊ
(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ ꢞ+ ꢊꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ $ꢊꢑ('ꢊ% ꢚ& 'ꢞꢉꢉꢊ'ꢘ(ꢉ-
ꢘꢈꢊ%ꢊ $ꢊꢑ('ꢊ% (ꢉ ꢆ C$ꢆ(%&ꢜ'ꢈꢆ(ꢉD (ꢉ ꢆ ꢙꢆꢉꢉꢊꢛ ꢆ% ꢗꢛꢊ%ꢊꢉꢘꢊ$
(ꢉ Figure 15ꢒ
#+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢛꢊEꢅꢊ%ꢘ% (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('(ꢉ- +ꢛꢞꢙ ꢘꢈꢊ ꢀ,ꢋ" (ꢘ
ꢝ(ꢇꢇ ꢆ%%ꢊꢛꢘ ꢘꢈꢊ ꢜ#7ꢎꢍ ꢗ(ꢉ ꢏꢊꢒ-ꢒ" ꢘꢞ--ꢇꢊ CꢇꢞꢝDꢐꢒ ꢂꢉ'ꢊ ꢘꢈꢊ
ꢀ,ꢋ ꢈꢆ% $ꢊꢘꢊ'ꢘꢊ$ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ" (ꢘ ꢝ(ꢇꢇ (%%ꢅꢊ ꢆꢉ
#ꢌꢀ: ꢏ#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊꢐ %(-ꢉꢆꢇ ꢚꢆ'3 ꢘꢞ ꢘꢈꢊ ꢄꢋꢌꢍꢎꢒ
Bꢈꢊꢉ ꢘꢈꢊ ꢀ,ꢋ %ꢊꢉ$% ꢘꢈꢊ #ꢌꢀ: %(-ꢉꢆꢇ ꢘꢞ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (ꢘ (%
(ꢉ+ꢞꢛꢙ(ꢉ- ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢘꢈꢆꢘ (ꢘ% (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ (% ꢆꢚꢞꢅꢘ ꢘꢞ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
1=
XR88C681
;
ꢀꢀ
ꢜ#7ꢎ
ꢜ#7ꢎꢍ
ꢜ#ꢌꢀ:
ꢜ#7ꢎꢍ
ꢜ#ꢌꢀ:
ꢜ#7ꢎꢍ
ꢜ#7ꢎꢍ
ꢜ#ꢌꢀ:
;
ꢀꢀ
#2#
#2ꢂ
#2#
#2ꢂ
#2#
#2ꢂ
#2#
#2ꢂ
CPU
ꢜ#ꢌꢀ:
ꢜ#ꢌꢀ:
8#082ꢃꢎ
9ꢂB2ꢃꢎ
,ꢍ#ꢂꢍ#ꢎG
Figure 15. A Diagram of Numerous DUARTs Configured in an Interrupt
Daisy Chain (for Z-Mode Operation)
#ꢉ ꢆ$$(ꢘ(ꢞꢉ ꢘꢞ ꢘꢈꢊ ꢜ#7ꢎꢍ ꢆꢉ$ ꢜ#ꢌꢀ: ꢗ(ꢉ%" ꢘꢈꢊ ?ꢜꢁꢞ$ꢊ
ꢄꢋꢌꢍꢎ ꢆꢇ%ꢞ ꢅ%ꢊ% ꢘꢈꢊ #2# ꢆꢉ$ #2ꢂ ꢗ(ꢉ%L ꢝꢈ('ꢈ ꢆꢛꢊ $ꢊ+(ꢉꢊ$
ꢆ% +ꢞꢇꢇꢞꢝ%4
ꢁ ꢌꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ" ꢛꢊEꢅꢊ%ꢘꢊ$ ꢚ& ꢘꢈꢊ $ꢊꢑ('ꢊ" ꢈꢆ% Mꢅ%ꢘ ꢚꢊꢊꢉ
%ꢊꢛꢑ('ꢊ$
#+ ꢆꢉ& ꢞ+ ꢘꢈꢊ%ꢊ 'ꢞꢉ$(ꢘ(ꢞꢉ% ꢆꢛꢊ +ꢆꢇ%ꢊ" ꢘꢈꢊꢉ ꢘꢈꢊ #2ꢂ ꢗ(ꢉ ꢝ(ꢇꢇ ꢚꢊ
ꢆꢘ ꢆ ꢇꢞ-(' CꢇꢞꢝDꢒ
IEI - Interrupt Enable Input
Note:
Once the IEO pin has toggled “low”, and the CPU has ac-
knowledged theinterruptrequestand hascompletedtheinter-
rupt service routine, the IEO pin will remain “low” until the user
invokes the “RESET IUS” command (see Table 3). Therefore,
if the DUART is going to operate in the Z-Mode, the user must
include the “RESET IUS” Command at the very end of the
DUART interrupt service routine.
ꢎꢈ(% ꢆ'ꢘ(ꢑꢊꢜꢈ(-ꢈ (ꢉꢗꢅꢘ (% ꢞꢉꢇ& ꢆꢑꢆ(ꢇꢆꢚꢇꢊ (+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (%
'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊꢒ #+ ꢘꢈ(% (ꢉꢗꢅꢘ (% ꢆꢘ ꢆ
ꢇꢞ-(' Cꢈ(-ꢈD ꢘꢈꢊꢉ ꢆꢇꢇ ꢅꢉꢙꢆ%3ꢊ$ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ%" +ꢛꢞꢙ
ꢘꢈ(% ꢄꢋꢌꢍꢎ" ꢆꢛꢊ ꢊꢉꢆꢚꢇꢊ$ꢒ
Note:
Those interrupts which have been masked out by the IMR are
still disabled. However, if this input is at a logic “low”, then all
interrupts (whether masked or unmasked) are disabled.
Hence, IEI can act to globally disable all DUART interrupt
requests.
System Level Application of the IEI and IEO pins
Figure 15 $ꢊꢗ('ꢘ% ꢆ %ꢊꢛ(ꢊ% ꢞ+ ꢄꢋꢌꢍꢎ% 'ꢞꢉꢉꢊ'ꢘꢊ$ (ꢉ ꢆ
$ꢆ(%&ꢜ'ꢈꢆ(ꢉ +ꢆ%ꢈ(ꢞꢉꢒ #ꢉ ꢘꢈ(% +(-ꢅꢛꢊ" ꢘꢈꢊ ꢇꢊ+ꢘꢜꢙꢞ%ꢘ ꢄꢋꢌꢍꢎ
ꢈꢆ% ꢘꢈꢊ ꢈ(-ꢈꢊ%ꢘ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛ(ꢞꢛ(ꢘ&ꢒ ꢎꢈ(% (% ꢚꢊ'ꢆꢅ%ꢊ ꢘꢈ(%
ꢄꢋꢌꢍꢎH% #2# (ꢉꢗꢅꢘ (% ꢈꢆꢛ$ꢝ(ꢛꢊ$ ꢘꢞ ;''ꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢘꢈꢊ
ꢅꢉꢙꢆ%3ꢊ$ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ%" +ꢛꢞꢙ ꢘꢈ(% ꢄꢋꢌꢍꢎ ꢆꢛꢊ
ꢆꢇꢝꢆ&% ꢊꢉꢆꢚꢇꢊ$ꢒ ꢎꢈꢊ ꢄꢋꢌꢍꢎ $ꢊꢑ('ꢊ" ꢇꢞ'ꢆꢘꢊ$ Mꢅ%ꢘ ꢘꢞ ꢘꢈꢊ
ꢛ(-ꢈꢘ ꢞ+ ꢘꢈꢊ Cꢈ(-ꢈꢊ%ꢘ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛ(ꢞꢛ(ꢘ&D $ꢊꢑ('ꢊ (% ꢞ+ ꢆ ꢇꢞꢝꢊꢛ
(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛ(ꢞꢛ(ꢘ&ꢒ ꢎꢈ(% (% ꢚꢊ'ꢆꢅ%ꢊ ꢘꢈꢊ #2# (ꢉꢗꢅꢘ ꢞ+ ꢘꢈ(% ꢇꢞꢝꢊꢛ
ꢗꢛ(ꢞꢛ(ꢘ& $ꢊꢑ('ꢊ (% 'ꢞꢉꢉꢊ'ꢘꢊ$ ꢘꢞ ꢘꢈꢊ #2ꢂ ꢞꢅꢘꢗꢅꢘ ꢞ+ ꢘꢈꢊ
ꢈ(-ꢈꢊ%ꢘ ꢗꢛ(ꢞꢛ(ꢘ& ꢄꢋꢌꢍꢎꢒ Bꢈꢊꢉꢊꢑꢊꢛ ꢘꢈꢊ Cꢈ(-ꢈꢊ%ꢘ ꢗꢛ(ꢞꢛ(ꢘ&D
$ꢊꢑ('ꢊ ꢛꢊEꢅꢊ%ꢘ% ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ" (ꢘ% #2ꢂ ꢞꢅꢘꢗꢅꢘ ꢝ(ꢇꢇ ꢘꢞ--ꢇꢊ
CꢇꢞꢝDꢒ ꢎꢈ(% ꢝ(ꢇꢇ (ꢉ ꢘꢅꢛꢉ" $(%ꢆꢚꢇꢊ ꢘꢈꢊ Cꢇꢞꢝꢊꢛ ꢗꢛ(ꢞꢛ(ꢘ&D $ꢊꢑ('ꢊ
IEO - Interrupt Enable Output
ꢎꢈ(% ꢆ'ꢘ(ꢑꢊꢜꢈ(-ꢈ ꢞꢅꢘꢗꢅꢘ (% ꢞꢉꢇ& ꢆꢑꢆ(ꢇꢆꢚꢇꢊ (+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (%
'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊꢒ ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ (% ꢞ+ꢘꢊꢉ
ꢘ(ꢙꢊ% 'ꢞꢉꢉꢊ'ꢘꢊ$ ꢘꢞ ꢘꢈꢊ #2# (ꢉꢗꢅꢘ ꢞ+ ꢆꢉꢞꢘꢈꢊꢛ ꢏꢇꢞꢝꢊꢛ ꢗꢛ(ꢞꢛ(ꢘ&ꢐ
$ꢊꢑ('ꢊꢒ ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ (% Cꢈ(-ꢈD (+ ꢆꢇꢇ ꢞ+ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ-
'ꢞꢉ$(ꢘ(ꢞꢉ% ꢆꢛꢊ ꢘꢛꢅꢊꢒ
ꢁ ꢎꢈꢊ $ꢊꢑ('ꢊH% #2# (ꢉꢗꢅꢘ (% ꢆꢘ ꢆ ꢇꢞ-(' Cꢈ(-ꢈD
ꢁ ꢎꢈꢊ $ꢊꢑ('ꢊ (% ꢉꢞꢘ ꢛꢊEꢅꢊ%ꢘ(ꢉ- ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ +ꢛꢞꢙ ꢘꢈꢊ
ꢀ,ꢋ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
1ꢖ
XR88C681
+ꢛꢞꢙ (%%ꢅ(ꢉ- ꢆꢉ& (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ% ꢘꢞ ꢘꢈꢊ ꢀ,ꢋꢒ ꢎꢈ(%
Cꢇꢞꢝꢊꢛ ꢗꢛ(ꢞꢛ(ꢘ&D ꢄꢋꢌꢍꢎ ꢝ(ꢇꢇ ꢚꢊ ꢗꢛꢞꢈ(ꢚ(ꢘꢊ$ +ꢛꢞꢙ (%%ꢅ(ꢉ-
(ꢉꢘꢊꢛꢛꢅꢗꢘ% ꢅꢉꢘ(ꢇ ꢘꢈꢊ #2ꢂ ꢗ(ꢉ ꢞ+ ꢘꢈꢊ Cꢈ(-ꢈꢊ%ꢘ ꢗꢛ(ꢞꢛ(ꢘ&D ꢄꢋꢌꢍꢎ
ꢈꢆ% ꢘꢞ--ꢇꢊ$ Cꢈ(-ꢈDꢒ
ꢛ(-ꢈꢘ ꢙꢞ%ꢘ ꢄꢋꢌꢍꢎ ꢈꢆ% ꢘꢈꢊ ꢇꢞꢝꢊ%ꢘꢜ(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛ(ꢞꢛ(ꢘ&
ꢚꢊ'ꢆꢅ%ꢊ (ꢘ% C(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘD 'ꢆꢗꢆꢚ(ꢇ(ꢘ& 'ꢆꢉ ꢚꢊ $(%ꢆꢚꢇꢊ$
ꢚ& ꢘꢈꢊ ꢆ'ꢘ(ꢞꢉ% ꢞ+ ꢆꢉ& ꢞꢉꢊ ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ% ꢘꢞ ꢘꢈꢊ ꢇꢊ+ꢘꢒ
Figure 16 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ ꢘ(ꢙ(ꢉ- $(ꢆ-ꢛꢆꢙ $ꢊꢗ('ꢘ(ꢉ- ꢘꢈꢊ
%ꢊEꢅꢊꢉ'ꢊ ꢞ+ ꢊꢑꢊꢉꢘ% ꢘꢈꢆꢘ ꢝ(ꢇꢇ ꢞ''ꢅꢛ $ꢅꢛ(ꢉ- ꢆꢉ$ +ꢞꢇꢇꢞꢝ(ꢉ- ꢆꢉ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢍꢊEꢅꢊ%ꢘ +ꢛꢞꢙ ꢘꢈꢊ ꢄꢋꢌꢍꢎꢒ
ꢍꢊ+ꢊꢛꢛ(ꢉ-" ꢞꢉ'ꢊ ꢆ-ꢆ(ꢉ" ꢘꢞ Figure 15" ꢘꢈꢊ +ꢅꢛꢘꢈꢊꢛ ꢘꢞ ꢘꢈꢊ ꢛ(-ꢈꢘ
ꢆ ꢄꢋꢌꢍꢎ $ꢊꢑ('ꢊ (%" ꢘꢈꢊ ꢇꢞꢝꢊꢛ (ꢘ% (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢗꢛ(ꢞꢛ(ꢘ&ꢒ ꢎꢈꢊ
ꢜ#7ꢎꢍ
ꢜ#ꢌꢀ:
ꢜꢍꢄ
ꢄꢕ ꢜ ꢄ>
#2#
9ꢂꢌꢎ
7ꢂꢎ ;ꢌ9#ꢄ
;2ꢀꢎꢂꢍ
9ꢂꢌꢎ
#2ꢂ
ꢍꢊ%ꢊꢘ #ꢋꢃ
ꢀꢞꢙꢙꢆꢉ$
Figure 16. Timing Diagram Illustrating the Sequence of Events Occurring Between the
DUART and the CPU During an Interrupt Request/Acknowledge and Servicing
Additional Things to Note About Z-Mode Operation
ꢁ =ꢕ=/• ,
ꢁ =ꢕꢓ=/ ꢜ =ꢕ6=/• ,
Please note that it is possible to interface the 80X86
Family of microprocessors to an I-Mode DUART,
however, additional components and design complexity
would be required in order to accomplish thisꢒ ꢎꢈꢊ
ꢘꢊ'ꢈꢉ(Eꢅꢊ.ꢆꢗꢗꢛꢞꢆ'ꢈꢊ% ꢘꢞ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢈꢊ ?ꢜꢁꢞ$ꢊ ꢄꢋꢌꢍꢎ
ꢘꢞ ꢘꢈꢊ%ꢊ ꢙ('ꢛꢞꢗꢛꢞ'ꢊ%%ꢞꢛ% (% ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ $ꢊꢘꢆ(ꢇ" (ꢉ ꢘꢈꢊ
+ꢞꢇꢇꢞꢝ(ꢉ- %ꢊ'ꢘ(ꢞꢉ%ꢒ
?ꢜꢁꢞ$ꢊ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ (% %ꢅꢗꢗꢞꢛꢘꢊ$ ꢚ& ꢆꢇꢇ ?(ꢇꢞ- ,ꢊꢛ(ꢗꢈꢊꢛꢆꢇ
'ꢞꢙꢗꢞꢉꢊꢉꢘ%ꢒ ꢌꢇꢇ ?(ꢇꢞ- ,ꢊꢛ(ꢗꢈꢊꢛꢆꢇ 'ꢞꢙꢗꢞꢉꢊꢉꢘ% ꢈꢆꢑꢊ ꢆꢉ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ ꢍꢊ-(%ꢘꢊꢛ" #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊ ꢏ#ꢌꢀ:ꢐ
(ꢉꢗꢅꢘ" #2# (ꢉꢗꢅꢘ" ꢆꢉ$ ꢆꢉ #2ꢂ ꢞꢅꢘꢗꢅꢘꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" Figure 15
'ꢞꢅꢇ$ ꢈꢆꢑꢊ ꢊꢆ%(ꢇ& (ꢉ'ꢇꢅ$ꢊ$ %ꢞꢙꢊ ꢞꢘꢈꢊꢛ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ
'ꢞꢙꢗꢞꢉꢊꢉꢘ%" (ꢉ ꢆ$$(ꢘ(ꢞꢉ ꢘꢞ ꢞꢛ (ꢉ ꢇ(ꢊꢅ ꢞ+ ꢄꢋꢌꢍꢎ%ꢒ
ꢌ% ꢙꢊꢉꢘ(ꢞꢉꢊ$ ꢊꢆꢛꢇ(ꢊꢛ" ?ꢜꢁꢞ$ꢊ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ (% ꢛꢊ'ꢞꢙꢙꢊꢉ$ꢊ$
(+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% ꢘꢞ ꢚꢊ (ꢉꢘꢊꢛ+ꢆ'ꢊ$ ꢘꢞ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ-
ꢗꢛꢞ'ꢊ%%ꢞꢛ%ꢒ
C.6.2.1 Z-80 Microprocessor
ꢎꢈꢊ ?ꢜ=ꢕ• , 'ꢞꢉ%(%ꢘ% ꢞ+ ꢆꢉ = ꢚ(ꢘ ꢄꢆꢘꢆ *ꢅ%" ꢆ ꢔ/ ꢚ(ꢘ ꢌ$$ꢛꢊ%%
*ꢅ% ꢆꢉ$ ꢉꢅꢙꢊꢛꢞꢅ% 'ꢞꢉꢘꢛꢞꢇ ꢗ(ꢉ%ꢒ ꢎꢈꢊ ?ꢜ=ꢕ• , (% ꢆ ꢑꢊꢛ&
+ꢇꢊ!(ꢚꢇꢊ ꢗꢛꢞ'ꢊ%%ꢞꢛ ꢝꢈ('ꢈ 'ꢆꢉ ꢆ'ꢘꢅꢆꢇꢇ& (ꢉꢘꢊꢛ+ꢆ'ꢊ ꢘꢞ ꢊ(ꢘꢈꢊꢛ ꢆ
?ꢜꢁꢞ$ꢊ ꢞꢛ ꢆꢉ #ꢜꢁꢞ$ꢊ ꢄꢋꢌꢍꢎ $ꢊꢑ('ꢊꢒ ꢎꢈ(% (% ꢚꢊ'ꢆꢅ%ꢊ ꢘꢈꢊ
ꢁ ?ꢜ=ꢕ ꢁ('ꢛꢞꢗꢛꢞ'ꢊ%%ꢞꢛ ꢏ#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢞ$ꢊ ꢓꢐ
ꢁ =ꢕ==• ꢀ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
<ꢕ
XR88C681
?ꢜ=ꢕ• , 'ꢆꢉ ꢚꢊ 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢞꢉꢊ ꢞ+ ꢘꢈꢛꢊꢊ
$(++ꢊꢛꢊꢉꢘ C(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢙꢞ$ꢊ%Dꢒ ꢎꢈꢊ ?ꢜ=ꢕ (% ꢆꢇ%ꢞ ꢆ ꢇ(ꢘꢘꢇꢊ ꢚ(ꢘ ꢇꢊ%%
'ꢞꢙꢗꢇ('ꢆꢘꢊ$ ꢘꢞ (ꢉꢘꢊꢛ+ꢆ'ꢊ ꢘꢞ ꢏꢘꢈꢆꢉ %ꢞꢙꢊ ꢞ+ ꢘꢈꢊ • ,.• ꢀ%
ꢗꢛꢊꢑ(ꢞꢅ%ꢇ& ꢙꢊꢉꢘ(ꢞꢉꢊ$ꢐ ꢚꢊ'ꢆꢅ%ꢊ (ꢘ% ꢆ$$ꢛꢊ%% ꢆꢉ$ $ꢆꢘꢆ ꢚꢅ%
ꢆꢛꢊ ꢉꢞꢘ ꢙꢅꢇꢘ(ꢗꢇꢊ!ꢊ$ꢒ Figure 17 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ %'ꢈꢊꢙꢆꢘ(' ꢞ+
ꢘꢈꢊ ꢗ(ꢉ ꢞꢅꢘ ꢞ+ ꢘꢈꢊ ?ꢜ=ꢕ• ,ꢒ
ꢌꢔꢔ
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Z80 CPU
;
ꢀꢀ
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ꢜ*ꢋꢃꢌ:
ꢓꢓ
ꢓꢔ
ꢜBꢍ
ꢜꢍꢄ
ꢓꢕ
Figure 17. Pin Out of the Z80 CPU Device
ꢎꢈꢊ ?ꢜ=ꢕ ꢀ,ꢋ ꢝ(ꢇꢇ %ꢅꢗꢗꢞꢛꢘ ꢍꢊꢆ$.Bꢛ(ꢘꢊ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ%
ꢏ#.ꢂ ,ꢞꢛꢘ ꢍꢊꢆ$ꢐ" ꢜ#ꢂB ꢏ#.ꢂ ,ꢞꢛꢘ Bꢛ(ꢘꢊꢐ ꢞꢛ ꢜ#ꢌꢀ:.ꢜ#7ꢎꢌ
ꢏ#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊꢐ ꢗ(ꢉ%ꢒ 2ꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ +ꢅꢉ'ꢘ(ꢞꢉ%
'ꢆꢉ ꢚꢊ $ꢊꢛ(ꢑꢊ$ +ꢛꢞꢙ ꢘꢈꢊ ꢜꢍꢄ" ꢜBꢍ" ꢜ#ꢂꢍ)" ꢜꢁꢍ2) ꢆꢉ$
ꢜꢁꢔ ꢗ(ꢉ%ꢒ Figure 18 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ %'ꢈꢊꢙꢆꢘ(' ꢞ+ ꢘꢈꢊ ?ꢜ=ꢕ
ꢀ,ꢋ ꢁꢞ$ꢅꢇꢊ" ꢝꢈ('ꢈ %ꢈꢞꢝ% ꢈꢞꢝ ꢞꢉ'ꢊ 'ꢆꢉ ꢊ!ꢘꢛꢆ'ꢘ ꢘꢈꢊ
'ꢞꢉꢘꢛꢞꢇ ꢚꢅ% %(-ꢉꢆꢇ% +ꢛꢞꢙ ꢘꢈꢊ%ꢊ ꢀ,ꢋ 'ꢞꢉꢘꢛꢞꢇ ꢗ(ꢉ%ꢒ
ꢚꢊꢘꢝꢊꢊꢉ ꢙꢊꢙꢞꢛ& ꢆꢉ$ #.ꢂꢒ ꢎꢈꢊ ?ꢜ=ꢕ $ꢞꢊ% ꢛꢊEꢅ(ꢛꢊ %ꢞꢙꢊ
ꢆ$$(ꢘ(ꢞꢉꢆꢇ -ꢇꢅꢊ ꢇꢞ-(' (ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ (ꢉꢘꢊꢛ+ꢆ'ꢊ $(ꢛꢊ'ꢘꢇ& ꢘꢞ
ꢙꢊꢙꢞꢛ& ꢆꢉ$ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ%ꢒ ꢞꢛ (ꢉ%ꢘꢆꢉ'ꢊ" ꢘꢈꢊ ?ꢜ=ꢕ
ꢀ,ꢋ $ꢊꢑ('ꢊ $ꢞꢊ% ꢉꢞꢘ 'ꢞꢙꢊ ꢝ(ꢘꢈ ꢘꢈꢊ 'ꢞꢉꢘꢛꢞꢇ ꢚꢅ% %(-ꢉꢆꢇ%4
ꢜꢁ2ꢁꢍ ꢏꢁꢊꢙꢞꢛ& ꢍꢊꢆ$ꢐ" ꢜꢁ2ꢁB ꢏꢁꢊꢙꢞꢛ& Bꢛ(ꢘꢊꢐ" ꢜ#ꢂꢍ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
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XR88C681
07ꢄ
A6;
ꢌꢕ ꢜ ꢌꢔ6
ꢄꢕ ꢜ ꢄ>
ꢀꢇꢞ'3 (ꢉꢗꢅꢘ
,8#
ꢜ#7ꢎ
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ꢜꢁ2ꢁB
ꢜBꢌ#ꢎ
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ꢜꢍ ꢃ8
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ꢜ#ꢂꢍ
ꢜꢁꢔ
ꢜ#7ꢎꢌ
ꢜꢍ2ꢃ2ꢎ
Figure 18. Schematic of Z-80 CPU Module
Z-80 CPU Interrupt Servicing Capability
2ꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢙꢞ$ꢊ% ꢅ%ꢊ ꢘꢈꢊ ꢜ#7ꢎ ꢗ(ꢉ ꢞ+ ꢘꢈꢊ ?ꢜ=ꢕ
ꢀ,ꢋ ꢆꢉ$ ꢝ(ꢇꢇ ꢚꢊ $(%'ꢅ%%ꢊ$ (ꢉ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- %ꢊ'ꢘ(ꢞꢉ%ꢒ
ꢎꢈꢊ ?ꢜ=ꢕ ꢀ,ꢋ 'ꢞꢉꢘꢆ(ꢉ% ꢘꢝꢞ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ ꢗ(ꢉ%4 ꢜ7ꢁ#
ꢆꢉ$ ꢜ#7ꢎꢒ ꢜ7ꢁ# (% ꢘꢈꢊ C7ꢞꢉꢜꢁꢆ%3ꢆꢚꢇꢊD (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ
(ꢉꢗꢅꢘ ꢗ(ꢉL ꢆꢉ$ ꢜ#7ꢎ (% ꢘꢈꢊ Cꢁꢆ%3ꢆꢚꢇꢊD (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ
(ꢉꢗꢅꢘ ꢗ(ꢉꢒ ꢞꢛ ꢘꢈꢊ %ꢆ3ꢊ ꢞ+ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢞ ꢘꢈꢊ ꢄꢋꢌꢍꢎ" ꢝꢊ ꢆꢛꢊ
ꢞꢉꢇ& 'ꢞꢉ'ꢊꢛꢉꢊ$ ꢝ(ꢘꢈ ꢘꢈꢊ ꢜ#7ꢎ ꢗ(ꢉꢒ
External Vectored Interrupt Processing (Interrupt
Mode 0)
ꢎꢈꢊ ?ꢜ=ꢕ • , ꢝ(ꢇꢇ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈ(% (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢙꢞ$ꢊ (+ ꢘꢈꢊ C#ꢁ ꢕD
(ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ ꢈꢆ% ꢚꢊꢊꢉ ꢊ!ꢊ'ꢅꢘꢊ$ꢒ Bꢈꢊꢉꢊꢑꢊꢛ ꢘꢈꢊ ꢜ#7ꢎ ꢗ(ꢉ (%
ꢆ%%ꢊꢛꢘꢊ$ ꢚ& ꢆ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ ꢛꢊEꢅꢊ%ꢘ(ꢉ- ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ"
ꢘꢈꢊ ꢀ,ꢋ ꢝ(ꢇꢇ 'ꢞꢙꢗꢇꢊꢘꢊ (ꢘ% 'ꢅꢛꢛꢊꢉꢘ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉꢒ ꢌ+ꢘꢊꢛ
'ꢞꢙꢗꢇꢊꢘ(ꢞꢉ ꢞ+ ꢘꢈ(% (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ" ꢘꢈꢊ ꢀ,ꢋ ꢙꢞ$ꢅꢇꢊ ꢝ(ꢇꢇ ꢆ%%ꢊꢛꢘ
ꢜ#7ꢎꢌ ꢏꢘꢞ--ꢇꢊ CꢇꢞꢝDꢐꢒ ꢜ#7ꢎꢌ (% ꢘꢈꢊ ꢆ'ꢘ(ꢑꢊꢜꢇꢞꢝ C#ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊD %(-ꢉꢆꢇ ꢘꢈꢆꢘ ꢘꢈꢊ ꢀ,ꢋ ꢙꢞ$ꢅꢇꢊ ꢞꢅꢘꢗꢅꢘ% (ꢉ
ꢞꢛ$ꢊꢛ ꢘꢞ (ꢉ(ꢘ(ꢆꢘꢊ ꢘꢈꢊ ꢗꢛꢞ'ꢊ%% ꢞ+ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('(ꢉ-ꢒ Bꢈꢊꢉ
ꢘꢈꢊ ?ꢜ=ꢕ ꢀ,ꢋ ꢞꢗꢊꢛꢆꢘꢊ% (ꢉ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢞ$ꢊ ꢕ" (ꢘ (%
ꢎꢈꢊ ?ꢜ=ꢕ ꢀ,ꢋ 'ꢆꢉ ꢚꢊ 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢞꢉꢊ ꢞ+
ꢘꢈꢛꢊꢊ $(++ꢊꢛꢊꢉꢘ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢙꢞ$ꢊ%4
ꢁ 2!ꢘꢊꢛꢉꢆꢇ ;ꢊ'ꢘꢞꢛꢊ$
ꢁ ꢄ(ꢛꢊ'ꢘ
ꢁ C,ꢊꢛ(ꢗꢈꢊꢛꢆꢇD ;ꢊ'ꢘꢞꢛꢊ$
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
<ꢓ
XR88C681
ꢆꢝꢆ(ꢘ(ꢉ- Cꢑꢊ'ꢘꢞꢛ (ꢉ+ꢞꢛꢙꢆꢘ(ꢞꢉD ꢞꢉ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ%" +ꢞꢇꢇꢞꢝ(ꢉ-
ꢘꢈꢊ ꢆ%%ꢊꢛꢘ(ꢞꢉ ꢞ+ ꢜ#7ꢎꢌꢒ #ꢉ ꢘꢈ(% 'ꢆ%ꢊ ꢏ+ꢞꢛ ꢘꢈ(% (ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢙꢞ$ꢊꢐ" ꢘꢈ(% Cꢑꢊ'ꢘꢞꢛD (ꢉ+ꢞꢛꢙꢆꢘ(ꢞꢉ (% ꢘꢈꢊ ꢞꢗꢜ'ꢞ$ꢊ +ꢞꢛ ꢞꢉꢊ ꢞ+
ꢘꢈꢊ ꢍ2ꢃꢎꢌꢍꢎ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ% ꢏꢍꢃꢎꢐꢒ ꢎꢈꢊ ?ꢜ=ꢕ ꢀ,ꢋ
%ꢅꢗꢗꢞꢛꢘ% ꢅꢗ ꢘꢞ ꢊ(-ꢈꢘ $(++ꢊꢛꢊꢉꢘ ꢍꢃꢎ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ% ꢏꢍꢃꢎꢕ ꢜ
ꢍꢃꢎ1=8ꢐꢒ ꢎꢈꢊ%ꢊ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ% ꢆꢛꢊ ꢞꢉꢊꢜꢚ&ꢘꢊ 'ꢆꢇꢇ% ꢘꢞ
%ꢗꢊ'(+(' ꢇꢞ'ꢆꢘ(ꢞꢉ% ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢀ,ꢋH% ꢙꢊꢙꢞꢛ& %ꢗꢆ'ꢊ" ꢝꢈꢊꢛꢊ
ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ ꢛꢊ%($ꢊ%ꢒ
Table 12 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ ꢇ(%ꢘ ꢞ+ ꢘꢈꢊ%ꢊ ꢍ2ꢃꢎꢌꢍꢎ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ%"
ꢘꢈꢊ ꢞꢗꢜ'ꢞ$ꢊ% ꢆꢉ$ ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- ꢍ2ꢃꢎꢌꢍꢎ
ꢆ$$ꢛꢊ%%ꢊ%ꢒ
ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ #ꢜꢁꢞ$ꢊ ꢆꢉ$ ꢘꢈꢆꢘ ꢘꢈꢊ ?ꢜ=ꢕ (%
ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢞ$ꢊ ꢕꢒ
Direct Interrupt Processing (Interrupt Mode 1)
ꢎꢈꢊ ?ꢜ=ꢕ • , ꢝ(ꢇꢇ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈ(% (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢙꢞ$ꢊ (+ ꢘꢈꢊ C#ꢁ ꢔD
(ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ ꢈꢆ% ꢚꢊꢊꢉ ꢊ!ꢊ'ꢅꢘꢊ$ꢒ Bꢈꢊꢉꢊꢑꢊꢛ ꢘꢈꢊ ꢜ#7ꢎ ꢗ(ꢉ (%
ꢆ%%ꢊꢛꢘꢊ$ ꢚ& ꢆ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ ꢛꢊEꢅꢊ%ꢘ(ꢉ- ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ"
ꢘꢈꢊ ꢀ,ꢋ ꢝ(ꢇꢇ 'ꢞꢙꢗꢇꢊꢘꢊ (ꢘ% 'ꢅꢛꢛꢊꢉꢘ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉꢒ ꢌ+ꢘꢊꢛꢝꢆꢛ$%"
ꢘꢈꢊ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢅꢉꢘꢊꢛ ꢝ(ꢇꢇ ꢆꢅꢘꢞꢙꢆꢘ('ꢆꢇꢇ& ꢚꢊ ꢇꢞꢆ$ꢊ$ ꢝ(ꢘꢈ ꢆ
ꢙꢊꢙꢞꢛ& ꢇꢞ'ꢆꢘ(ꢞꢉ ꢏꢗꢛꢊꢜ$ꢊꢘꢊꢛꢙ(ꢉꢊ$ ꢚ& ꢘꢈꢊ '(ꢛ'ꢅ(ꢘ $ꢊ%(-ꢉ ꢞ+
ꢘꢈꢊ ?ꢜ=ꢕ ꢀ,ꢋ $ꢊꢑ('ꢊꢐ ꢆꢉ$ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢝ(ꢇꢇ ꢚꢊ
ꢚꢛꢆꢉ'ꢈꢊ$ ꢘꢞ ꢘꢈꢆꢘ ꢇꢞ'ꢆꢘ(ꢞꢉ (ꢉ %&%ꢘꢊꢙ ꢙꢊꢙꢞꢛ&ꢒ #ꢉ ꢘꢈ(% 'ꢆ%ꢊ"
Op-Code (hex)
Mnemonic
Restart
ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢝꢞꢅꢇ$ ꢚꢛꢆꢉ'ꢈ ꢘꢞ ꢕꢕ1= (ꢉ ꢙꢊꢙꢞꢛ&ꢒ ꢎꢈꢊ
ꢔ/
Address (hex)
ꢅ%ꢊꢛ (% ꢛꢊ%ꢗꢞꢉ%(ꢚꢇꢊ +ꢞꢛ (ꢉ%ꢅꢛ(ꢉ- ꢘꢈꢆꢘ ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ
(ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ (% ꢆꢘ ꢘꢈꢆꢘ ꢗꢆꢛꢘ('ꢅꢇꢆꢛ ꢇꢞ'ꢆꢘ(ꢞꢉ (ꢉ
ꢙꢊꢙꢞꢛ&ꢒ ꢎꢈꢊ ?ꢜ=ꢕ ꢀ,ꢋ ꢙꢞ$ꢅꢇꢊ $ꢞꢊ% ꢉꢞꢘ ꢗꢛꢞꢑ($ꢊ ꢘꢈꢊ
ꢀ>
ꢀ
ꢄ>
ꢄ
2>
2
>
ꢍꢃꢎ ꢕ
ꢍꢃꢎ ꢕ=
ꢕꢕꢕꢕ
ꢕꢕꢕ=
ꢕꢕꢔꢕ
ꢕꢕꢔ=
ꢕꢕꢓꢕ
ꢕꢕꢓ=
ꢕꢕ1ꢕ
ꢕꢕ1=
ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ ꢝ(ꢘꢈ ꢆꢉ& %ꢞꢛꢘ ꢞ+
C#ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢍꢃꢎ ꢔꢕ
ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊDꢒ ꢎꢈꢊ ꢀ,ꢋ Mꢅ%ꢘ ꢗꢛꢞ'ꢊ%%ꢊ% ꢘꢈꢛꢞꢅ-ꢈ ꢘꢈꢊ
#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢊꢛꢑ('ꢊ ꢍꢞꢅꢘ(ꢉꢊ" ꢊꢇ(ꢙ(ꢉꢆꢘꢊ% ꢘꢈꢊ 'ꢆꢅ%ꢊꢏ%ꢐ ꢞ+ ꢘꢈꢊ
(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ ꢆꢉ$ ꢛꢊꢘꢅꢛꢉ% ꢘꢞ ꢉꢞꢛꢙꢆꢇ ꢞꢗꢊꢛꢆꢘ(ꢞꢉꢒ
ꢍꢃꢎ ꢔ=
ꢍꢃꢎ ꢓꢕ8
ꢍꢃꢎ ꢓ=8
ꢍꢃꢎ 1ꢕ8
ꢍꢃꢎ 1=8
Peripheral Vectored Interrupt Processing
(Interrupt Mode 2)
ꢎꢈꢊ ?ꢜ=ꢕ • , ꢝ(ꢇꢇ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈ(% (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢙꢞ$ꢊ (+ ꢘꢈꢊ C#ꢁ ꢓD
(ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ ꢈꢆ% ꢚꢊꢊꢉ ꢊ!ꢊ'ꢅꢘꢊ$ꢒ ꢎꢈ(% (ꢉꢘꢊꢛꢛꢅꢗꢘ Cꢙꢞ$ꢊD (%
ꢑꢊꢛ& ꢅ%ꢊ+ꢅꢇ (+ ꢘꢈꢊ ꢅ%ꢊꢛ ꢝ(%ꢈꢊ% ꢘꢞ 'ꢞꢉꢉꢊ'ꢘ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢛꢊEꢅꢊ%ꢘ ꢞꢅꢘꢗꢅꢘ% ꢞ+ %ꢊꢑꢊꢛꢆꢇ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ% ꢘꢞ ꢘꢈꢊ ꢞꢉꢊ ꢜ#7ꢎ
(ꢉꢗꢅꢘ ꢞ+ ꢘꢈꢊ ?ꢜ=ꢕ ꢀ,ꢋꢒ ꢎꢈ(% (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢙꢞ$ꢊ ꢆꢇꢇꢞꢝ% ꢘꢈꢊ
(ꢉꢘꢊꢛꢛꢅꢗꢘ(ꢉ- $ꢊꢑ('ꢊ ꢘꢞ ($ꢊꢉꢘ(+& (ꢘ%ꢊꢇ+ ꢆꢘ ꢆ 'ꢊꢛꢘꢆ(ꢉ ꢘ(ꢙꢊ" Mꢅ%ꢘ
ꢗꢛ(ꢞꢛ ꢘꢞ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('(ꢉ-ꢒ
Table 12. Z-80 CPU Restart Instructions
Used with Vectored Interrupts
ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢞꢉ'ꢊ ꢘꢈꢊ ꢀ,ꢋ ꢛꢊ'ꢊ(ꢑꢊ% ꢘꢈꢊ ꢞꢗꢜ'ꢞ$ꢊ +ꢞꢛ ꢞꢉꢊ ꢞ+
ꢘꢈꢊ%ꢊ ꢍ2ꢃꢎꢌꢍꢎ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ%" (ꢘ ꢝ(ꢇꢇ ꢚꢊ-(ꢉ ꢊ!ꢊ'ꢅꢘ(ꢉ- ꢘꢈ(%
(ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ ꢚ& ꢇꢞꢆ$(ꢉ- ꢘꢈꢊ ,ꢛꢞ-ꢛꢆꢙ ꢀꢞꢅꢉꢘꢊꢛ ꢝ(ꢘꢈ ꢘꢈꢊ
ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ Cꢍꢊ%ꢘꢆꢛꢘD ꢌ$$ꢛꢊ%%ꢒ ꢌ+ꢘꢊꢛꢝꢆꢛ$%" ꢗꢛꢞ-ꢛꢆꢙ
'ꢞꢉꢘꢛꢞꢇ ꢝ(ꢇꢇ ꢚꢊ ꢚꢛꢆꢉ'ꢈꢊ$ ꢘꢞ ꢘꢈꢊ Cꢍꢊ%ꢘꢆꢛꢘ ꢌ$$ꢛꢊ%%D ꢇꢞ'ꢆꢘ(ꢞꢉꢒ
Bꢈꢊꢉꢊꢑꢊꢛ ꢘꢈꢊ ꢜ#7ꢎ ꢗ(ꢉ (% ꢆ%%ꢊꢛꢘꢊ$ ꢚ& ꢆ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ
ꢛꢊEꢅꢊ%ꢘ(ꢉ- ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ" ꢘꢈꢊ ꢀ,ꢋ ꢝ(ꢇꢇ 'ꢞꢉꢘ(ꢉꢅꢊ ꢘꢞ 'ꢞꢙꢗꢇꢊꢘꢊ
(ꢘ% 'ꢅꢛꢛꢊꢉꢘ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉꢒ ꢂꢉ'ꢊ ꢘꢈ(% 'ꢅꢛꢛꢊꢉꢘ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ (%
'ꢞꢙꢗꢇꢊꢘꢊ$" ꢘꢈꢊ ꢀ,ꢋ ꢁꢞ$ꢅꢇꢊ ꢝ(ꢇꢇ ꢆ%%ꢊꢛꢘ ꢘꢈꢊ ꢜ#7ꢎꢌ %(-ꢉꢆꢇ ꢘꢞ
(ꢉ+ꢞꢛꢙ ꢘꢈꢊ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ ꢘꢈꢆꢘ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ (% ꢆꢚꢞꢅꢘ
ꢘꢞ ꢚꢊ-(ꢉꢒ ꢂꢉ'ꢊ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ(ꢉ- ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ $ꢊꢑ('ꢊ ꢈꢆ%
$ꢊꢘꢊ'ꢘꢊ$ ꢘꢈꢊ ꢜ#7ꢎꢌ ꢗꢅꢇ%ꢊ" (ꢘ ꢝ(ꢇꢇ ꢗꢇꢆ'ꢊ ꢆꢉ C(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢑꢊ'ꢘꢞꢛD
ꢞꢉ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ%ꢒ ꢎꢈ(% (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢑꢊ'ꢘꢞꢛ ꢝ(ꢇꢇ ꢚꢊ ꢛꢊꢆ$ ꢚ& ꢘꢈꢊ
ꢀ,ꢋ ꢆꢉ$ ꢘꢈꢊ ꢀ,ꢋ ꢝ(ꢇꢇ ꢚꢛꢆꢉ'ꢈ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢘꢞ ꢘꢈꢊ
ꢇꢞ'ꢆꢘ(ꢞꢉ ꢏꢛꢊ+ꢊꢛꢛꢊ$ ꢘꢞ ꢚ& ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢑꢊ'ꢘꢞꢛꢐꢒ Please note
that if the IEI input to the DUART (or Zilog peripheral
device) is “low” then the DUART (or Zilog peripheral
device) will be disabled from generating any interrupt
requests to the CPUꢒ
ꢞꢛ 2!ꢆꢙꢗꢇꢊ4
#+ ꢘꢈꢊ ꢞꢗꢜ'ꢞ$ꢊ 2> (% ꢇꢞꢆ$ꢊ$ ꢞꢉꢘꢞ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ% $ꢅꢛ(ꢉ- ꢘꢈꢊ
ꢔ/
ꢜ#7ꢎꢌ '&'ꢇꢊ" ꢘꢈ(% ꢞꢗꢜ'ꢞ$ꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$% ꢝ(ꢘꢈ ꢘꢈꢊ ꢍꢃꢎ ꢓꢕ8
(ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ ꢆꢉ$" ꢘꢈꢊ ꢀ,ꢋ ꢝ(ꢇꢇ ꢇꢞꢆ$ ꢕꢕꢓꢕ (ꢉꢘꢞ ꢘꢈꢊ ꢗꢛꢞ-ꢛꢆꢙ
ꢔ/
'ꢞꢅꢉꢘꢊꢛ ꢆꢉ$ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢝ(ꢘꢈ ꢚꢛꢆꢉ'ꢈ ꢘꢞ ꢘꢈꢆꢘ ꢇꢞ'ꢆꢘ(ꢞꢉ
(ꢉ ꢙꢊꢙꢞꢛ& ꢏ%ꢊꢊ Table 12ꢐꢒ ꢎꢈꢊ ꢅ%ꢊꢛ (% ꢛꢊ%ꢗꢞꢉ%(ꢚꢇꢊ +ꢞꢛ
(ꢉ%ꢅꢛ(ꢉ- ꢘꢈꢆꢘ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ ꢚꢊ-(ꢉ% ꢆꢘ ꢘꢈ(%
ꢇꢞ'ꢆꢘ(ꢞꢉ (ꢉ ꢙꢊꢙꢞꢛ&ꢒ
ꢌꢉ ꢊ!ꢆꢙꢗꢇꢊ ꢞ+ ꢆ '(ꢛ'ꢅ(ꢘ ꢛꢊꢆꢇ(I(ꢉ- ꢘꢈ(% +ꢞꢛꢙ ꢞ+ (ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢗꢛꢞ'ꢊ%%(ꢉ-" ꢝꢈ(ꢇꢊ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢞ ꢘꢈꢊ ꢄꢋꢌꢍꢎ" (% ꢗꢛꢊ%ꢊꢉꢘꢊ$
(ꢉ Section C.6.1.2ꢒ ꢎꢈ(% %ꢊ'ꢘ(ꢞꢉ $(%'ꢅ%%ꢊ% (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢈꢊ
ꢄꢋꢌꢍꢎ ꢘꢞ ꢘꢈꢊ =ꢕ=ꢕꢌ ꢀ,ꢋ ꢁꢞ$ꢅꢇꢊꢒ ꢎꢈ(% ꢊ!ꢆ'ꢘ %ꢆꢙꢊ
ꢆꢗꢗꢛꢞꢆ'ꢈ 'ꢞꢅꢇ$ ꢚꢊ ꢅ%ꢊ$ ꢝ(ꢘꢈ ꢘꢈꢊ ?ꢜ=ꢕ ꢀ,ꢋ" ꢗꢛꢞꢑ($ꢊ ꢘꢈꢆꢘ
ꢌꢉ ꢊ!ꢆꢙꢗꢇꢊ ꢞ+ ꢘꢈ(% ꢆꢗꢗꢛꢞꢆ'ꢈ (% ꢗꢛꢊ%ꢊꢉꢘꢊ$ Figure 19ꢒ #ꢉ
ꢘꢈ(% 'ꢆ%ꢊ ꢘꢈꢊ 5ꢍ==ꢀ/=ꢔ ꢄꢋꢌꢍꢎ (% 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ ꢞꢗꢊꢛꢆꢘꢊ
(ꢉ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊ ꢆꢉ$ (% (ꢉꢘꢊꢛ+ꢆ'ꢊ$ ꢘꢞ ꢘꢈꢊ ?ꢜ=ꢕ ꢀ,ꢋꢒ Bꢈꢊꢉ
ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢛꢊEꢅ(ꢛꢊ% (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('(ꢉ-" (ꢘ ꢝ(ꢇꢇ ꢆ%%ꢊꢛꢘ (ꢘ%
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
<1
XR88C681
ꢜ#7ꢎꢍ ꢞꢅꢘꢗꢅꢘꢒ ꢎꢈ(% ꢆ'ꢘ(ꢞꢉ ꢝ(ꢇꢇ" (ꢉ ꢘꢅꢛꢉ" 'ꢆꢅ%ꢊ ꢘꢈꢊ ꢜ#7ꢎ (ꢉꢗꢅꢘ
ꢞ+ ꢘꢈꢊ ꢀ,ꢋ ꢘꢞ ꢚꢊ ꢆ%%ꢊꢛꢘꢊ$ꢒ ꢂꢉ'ꢊ ꢘꢈꢊ ꢀ,ꢋ ꢈꢆ% 'ꢞꢙꢗꢇꢊꢘꢊ$
(ꢘ% 'ꢅꢛꢛꢊꢉꢘ (ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ" ꢘꢈꢊ ꢀ,ꢋ ꢁꢞ$ꢅꢇꢊ ꢝ(ꢇꢇ ꢆ%%ꢊꢛꢘ ꢘꢈꢊ
ꢜ#7ꢎꢌ %(-ꢉꢆꢇꢒ ꢎꢈ(% ꢝ(ꢇꢇ (ꢉ ꢘꢅꢛꢉ ꢆ%%ꢊꢛꢘ ꢘꢈꢊ ꢜ#ꢌꢀ: ꢏ#ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊꢐ (ꢉꢗꢅꢘ ꢘꢞ ꢘꢈꢊ ꢄꢋꢌꢍꢎꢒ ꢎꢈꢊ ꢗꢅꢛꢗꢞ%ꢊ ꢞ+ ꢘꢈꢊ
ꢆ%%ꢊꢛꢘꢊ$ ꢜ#ꢌꢀ: %(-ꢉꢆꢇ (% ꢘꢞ (ꢉ+ꢞꢛꢙ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢘꢈꢆꢘ ꢘꢈꢊ
ꢑꢊꢛ& ꢉꢊ!ꢘ '&'ꢇꢊ ꢝ(ꢇꢇ ꢚꢊ ꢆꢉ C#ꢌꢀ:D ꢞꢛ C#ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊD '&'ꢇꢊꢒ ꢄꢋꢌꢍꢎ" (ꢉ ꢛꢊ%ꢗꢞꢉ%ꢊ ꢘꢞ ꢘꢈꢊ ꢜ#ꢌꢀ:
%(-ꢉꢆꢇ" ꢝ(ꢇꢇ ꢗꢇꢆ'ꢊ ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ
ꢍꢊ-(%ꢘꢊꢛ ꢏ#;ꢍꢐ ꢞꢉ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ%ꢒ ꢎꢈ(% $ꢆꢘꢆ ꢝ(ꢇꢇ ꢚꢊ ꢛꢊꢆ$ ꢚ&
ꢘꢈꢊ ꢀ,ꢋ" ꢆꢉ$ ꢗꢛꢞ-ꢛꢆꢙ 'ꢞꢉꢘꢛꢞꢇ ꢝ(ꢇꢇ ꢚꢊ ꢚꢛꢆꢉ'ꢈꢊ$ ꢘꢞ ꢘꢈꢊ
ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊꢒ #ꢉ ꢘꢈꢊ 'ꢆ%ꢊ ꢞ+ ꢘꢈꢊ
?ꢜ=ꢕ ꢀ,ꢋ" ꢘꢈ(% ꢇꢞ'ꢆꢘ(ꢞꢉ (% ꢆ ꢔ/ ꢚ(ꢘ ꢆ$$ꢛꢊ%% ꢝꢈ('ꢈ (%
$ꢊꢘꢊꢛꢙ(ꢉꢊ$ +ꢛꢞꢙ Table 13ꢒ
Most Significant Byte
Least Significant Byte
Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
ꢀꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ # ꢍꢊ-(%ꢘꢊꢛ ꢏꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢀ,ꢋꢐ
ꢎꢈꢊ > ꢁꢞ%ꢘ ꢃ(-ꢉ(+('ꢆꢉꢘ *(ꢘ% ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ;ꢊ'ꢘꢞꢛ
ꢍꢊ-(%ꢘꢊꢛ ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ
ꢕ
Note: The LSB of the IVR is always set to “0” once read by the CPU. Interrupt Service Routines must begin at even ddresses.
Table 13. The Relationship between the Contents of the Interrupt Vector Register (of the DUART)
and the location of the Interrupt Service Routine (Z-80 CPU)
ꢌ$$(ꢘ(ꢞꢉꢆꢇꢇ&" ꢘꢈꢊ ꢅ%ꢊꢛ ꢙꢅ%ꢘ ꢚꢊ ꢆꢝꢆꢛꢊ ꢞ+ ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢘꢈꢆꢘ ꢈꢊ.%ꢈꢊ ꢇꢞꢆ$% (ꢉꢘꢞ ꢘꢈꢊ # ꢍꢊ-(%ꢘꢊꢛ ꢞ+ ꢘꢈꢊ ꢀ,ꢋ" $ꢅꢛ(ꢉ- ꢛꢅꢉ ꢘ(ꢙꢊꢒ
+ꢛꢞꢙ ;'' ꢞꢛ ꢈ(-ꢈꢊꢛ
#2#
ꢗꢛ(ꢞꢛ(ꢘ& ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ
ꢌ$$ꢛꢊ%%
ꢄꢊ'ꢞ$ꢊꢛ
ꢀ(ꢛ'ꢅ(ꢘꢛ&
ꢌꢕ ꢜ ꢌꢔ6
ꢘꢞ ꢇꢞꢝꢊꢛ ꢗꢛ(ꢞꢛ(ꢘ&
ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ
#2ꢂ
ꢜꢀꢃ
ꢀꢃFꢄꢋꢌꢍꢎ
ꢌꢕ ꢜ ꢌ1
ꢌꢕ ꢜ ꢌ1
ꢄꢕ ꢜ ꢄ>
ꢄꢕ ꢜ ꢄ>
ꢜ#7ꢎ
ꢜ#7ꢎꢍ
ꢜBꢍ
ꢜꢍꢄ
ꢜꢁ2ꢁB
ꢜBꢍ
ꢜꢍꢄ
ꢜꢁ2ꢁꢍ
ꢜꢁꢍ2)
ꢜ#ꢂꢍ)
ꢁꢔ
ꢜ#7ꢎꢌ
ꢜ#ꢌꢀ:
Z80 CPU
XR88C681
Figure 19. Schematic of an Approach to Interface the DUART to the Z-80
CPU (for Z-Mode Operation)
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
<<
XR88C681
C.6.2.2 8086 Microprocessor
ꢎꢈꢊ =ꢕ=/ ꢙ('ꢛꢞꢗꢛꢞ'ꢊ%%ꢞꢛ (% ꢆ ꢔ/ ꢚ(ꢘ ꢙ('ꢛꢞꢗꢛꢞ'ꢊ%%ꢞꢛ ꢙꢆꢉꢅ+ꢆ'ꢘꢅꢛꢊ$ ꢚ& #ꢉꢘꢊꢇ ꢀꢞꢛꢗꢞꢛꢆꢘ(ꢞꢉꢒ Figure 20 ꢗꢛꢊ%ꢊꢉꢘ% ꢘꢈꢊ ꢗ(ꢉ ꢞꢅꢘ
$(ꢆ-ꢛꢆꢙ ꢞ+ ꢘꢈ(% #ꢀꢒ Please note that in (-ꢅꢛꢊ ꢓꢕ, pins 24 - 31 have some additional labels, located off to the right of the
package. These additional labels will be explained later in this text.
07ꢄ
ꢌꢄꢔ<
ꢌꢄꢔ1
ꢌꢄꢔꢓ
ꢌꢄꢔꢔ
ꢔ
ꢓ
1
<
6
<ꢕ
1ꢖ
1=
1>
;
ꢀꢀ
ꢌꢄꢔ6
ꢌꢔ/.ꢃ1
ꢌꢔ>.ꢃ<
1/ ꢌꢔ=.ꢃ6
16
ꢌꢄꢔꢕ
ꢌꢄꢖ
/
>
ꢌꢔꢖ.ꢃ/
ꢜ*82.ꢃ>
1<
11
1ꢓ
ꢌꢄ=
ꢌꢄ>
ꢌꢄ/
ꢌꢄ6
ꢌꢄ<
ꢌꢄ1
=
ꢖ
ꢁ7.ꢁ5
ꢜꢍꢄ
1ꢔ ꢜꢍ).ꢜ0ꢎꢕ
ꢏ8ꢂ9ꢄꢐ
ꢏ89ꢄꢌꢐ
ꢏꢜBꢍꢐ
ꢔꢕ
ꢔꢔ
ꢔꢓ
ꢔ1
ꢔ<
ꢔ6
ꢔ/
8086 CPU
ꢜꢍ).ꢜ0ꢎꢔ
ꢜ9ꢂꢀ:
1ꢕ
ꢓꢖ
ꢓ= ꢜꢃꢓ
ꢓ> ꢜꢃꢔ
ꢏꢁ.ꢜ#ꢂꢐ
ꢏꢄꢎ.ꢜꢍꢐ
ꢌꢄꢓ
ꢌꢄꢔ
ꢌꢄꢕ
7ꢁ#
ꢓ/
ꢓ6
ꢓ<
ꢓ1
ꢜꢃꢕ
ꢏꢜꢄ27ꢐ
ꢏꢌ92ꢐ
)ꢃꢕ
ꢔ>
)ꢃꢔ
ꢏꢜ#7ꢎꢌꢐ
#7ꢎꢍ ꢔ=
ꢜꢎ2ꢃꢎ
ꢔꢖ
ꢓꢕ
ꢀ9:
ꢓꢓ
ꢓꢔ
ꢍ2ꢌꢄG
ꢍ2ꢃ2ꢎ
07ꢄ
Figure 20. Pin Out of the 8086 Microprocessor Device
#ꢉꢘꢊꢇ ꢝꢊꢉꢘ ꢘꢞ -ꢛꢊꢆꢘ ꢇꢊꢉ-ꢘꢈ% ꢘꢞ 3ꢊꢊꢗ ꢘꢈꢊ ꢗ(ꢉ 'ꢞꢅꢉꢘ ꢞ+ ꢘꢈ(% #ꢀ
ꢇꢞꢝ ꢚ& ꢙꢅꢇꢘ(ꢗꢇꢊ!(ꢉ- ꢘꢈꢊ +ꢅꢉ'ꢘ(ꢞꢉ% ꢞ+ ꢙꢆꢉ& ꢞ+ ꢘꢈꢊ%ꢊ ꢗ(ꢉ%ꢒ
ꢎꢈ(% $ꢊꢑ('ꢊ 'ꢞꢉ%(%ꢘ% ꢞ+ ꢆ ꢔ/ ꢚ(ꢘ ꢄꢆꢘꢆ *ꢅ% ꢆꢉ$ ꢆ ꢓꢕ ꢚ(ꢘ
ꢌ$$ꢛꢊ%% *ꢅ%ꢒ ꢎꢈꢊ ꢄꢆꢘꢆ *ꢅ% (% ꢙꢅꢇꢘ(ꢗꢇꢊ!ꢊ$ ꢝ(ꢘꢈ ꢘꢈꢊ ꢇꢞꢝꢊꢛ
ꢔ/ ꢌ$$ꢛꢊ%% *(ꢘ% ꢏꢌꢕ ꢜ ꢌꢔ6ꢐ ꢘꢞ +ꢞꢛꢙ ꢌꢄꢕ ꢜ ꢌꢄꢔ6ꢒ ꢌ$$ꢛꢊ%%
*(ꢘ% ꢌꢔ/ ꢜ ꢌꢔꢖ ꢆꢛꢊ ꢙꢅꢇꢘ(ꢗꢇꢊ!ꢊ$ ꢝ(ꢘꢈ %ꢘꢆꢘꢅ% ꢚ(ꢘ% ꢃ1 ꢜ ꢃ/ ꢘꢞ
+ꢞꢛꢙ ꢌꢔ/.ꢃ1" ꢌꢔ>.ꢃ<" ꢌꢔ=.ꢃ6 ꢆꢉ$ ꢌꢔꢖ.ꢃ/ꢒ ꢌꢇꢇ ꢞ+ ꢘꢈꢊ%ꢊ
ꢗ(ꢉ% ꢆꢛꢊ ꢆ$$ꢛꢊ%% ꢇ(ꢉꢊ% $ꢅꢛ(ꢉ- ꢘꢈꢊ +(ꢛ%ꢘ ꢈꢆꢇ+ ꢞ+ ꢆ ꢙꢊꢙꢞꢛ&
'&'ꢇꢊꢒ 8ꢞꢝꢊꢑꢊꢛ" $ꢅꢛ(ꢉ- ꢘꢈꢊ %ꢊ'ꢞꢉ$ ꢈꢆꢇ+ ꢞ+ ꢆ ꢙꢊꢙꢞꢛ&
'&'ꢇꢊ" ꢘꢈꢊ%ꢊ ꢗ(ꢉ% ꢘꢈꢊꢉ ꢘꢆ3ꢊ ꢞꢉ ꢘꢈꢊ(ꢛ ꢆꢇꢘꢊꢛꢉꢆꢘꢊ +ꢅꢉ'ꢘ(ꢞꢉ%
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
<6
XR88C681
ꢏꢊꢒ-ꢒ" ꢌꢄꢕ ꢜ ꢌꢄꢔ6 ꢚꢊ'ꢞꢙꢊ% ꢄꢕ ꢜ ꢄꢔ6" ꢌꢔ/.ꢃ1 ꢜ ꢌꢔꢖ.ꢃ/
ꢚꢊ'ꢞꢙꢊ% ꢃ1 ꢜ ꢃ/ꢐꢒ ꢌ %ꢊ'ꢞꢉ$ -ꢛꢞꢅꢗ ꢞ+ ꢙꢅꢇꢘ(ꢗꢇꢊ!ꢊ$ ꢗ(ꢉ% (%
'ꢞꢉꢘꢛꢞꢇꢇꢊ$ ꢚ& ꢘꢈꢊ ꢁ7.ꢜꢁ5 (ꢉꢗꢅꢘ ꢗ(ꢉꢒ Bꢈꢊꢉ ꢘꢈ(% ꢗ(ꢉ (% ꢈ(-ꢈ"
ꢘꢈꢊ Cꢙ(ꢉD ꢙꢞ$ꢊ (% %ꢊꢇꢊ'ꢘꢊ$ ꢆꢉ$ ꢗ(ꢉ% ꢓ< ꢘꢈꢛꢞꢅ-ꢈ 1ꢔ ꢘꢆ3ꢊ ꢞꢉ
ꢘꢈꢊ 'ꢞꢉꢘꢛꢞꢇ $ꢊ+(ꢉ(ꢘ(ꢞꢉ% %ꢈꢞꢝꢉ ꢅꢉ$ꢊꢛ ꢘꢈꢊ ꢁ7.ꢜꢁ5 J ꢔ
'ꢞꢇꢅꢙꢉ (ꢉ
Table 14
ꢒ Bꢈꢊꢉ ꢘꢈꢊ =ꢕ=/• , ꢞꢗꢊꢛꢆꢘꢊ% (ꢉ ꢘꢈ(%
ꢙꢞ$ꢊ" (ꢘ ꢗꢛꢊ%ꢊꢉꢘ% ꢆ 'ꢞꢉꢘꢛꢞꢇ ꢚꢅ% ꢑꢊꢛ& %(ꢙ(ꢇꢆꢛ ꢘꢞ ꢘꢈꢆꢘ ꢞ+ ꢘꢈꢊ
=ꢕ=6• ," ꢆꢉ$ ꢛꢊEꢅ(ꢛꢊ% ꢞꢉꢇ& ꢆꢉ ꢆ$$ꢛꢊ%% ꢇꢆꢘ'ꢈ ꢆꢉ$ ꢆ 'ꢇꢞ'3
-ꢊꢉꢊꢛꢆꢘꢞꢛ ꢘꢞ +ꢞꢛꢙ ꢆ ꢀ,ꢋ ꢙꢞ$ꢅꢇꢊꢒ
Pin Number
MN/ꢜMX = 1 (Min Mode)
8ꢂ9ꢄ
MN/ꢜMX = 0 (Max Mode)
ꢓ<
ꢓ6
ꢓ/
ꢓ>
ꢓ=
ꢓꢖ
1ꢕ
1ꢔ
ꢜꢍ).ꢜ0ꢎꢕ
ꢜꢍ).ꢜ0ꢎꢔ
ꢜ9ꢂꢀ:
ꢜꢃꢓ
89ꢄꢌ
ꢜBꢍ
ꢁ.ꢜ#ꢂ
ꢄꢎ.ꢍ
ꢜꢄ27
ꢌ92
ꢜꢃꢔ
ꢜꢃꢕ
)ꢃꢕ
ꢜ#7ꢎꢌ
)ꢃꢔ
Table 14. MN/ꢜMX Mode and Function of Pins 24-31 of 8086 CPU Device.
Bꢈꢊꢉ ꢁ7.ꢜꢁ5 (% ꢇꢞꢝ" ꢘꢈꢊ =ꢕ=/• , (% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ Cꢙꢆ!D
ꢛꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘL ꢆꢉ$ #7ꢎꢍ (% ꢘꢈꢊ Cꢙꢆ%3ꢆꢚꢇꢊD (ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢛꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘꢒ #+ ꢘꢈꢊ =ꢕ=/• , (% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ Cꢙ(ꢉD
ꢙꢞ$ꢊ" ꢘꢈꢊꢉ ꢘꢈꢊ ꢜ#7ꢎꢌ ꢏ#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊꢐ ꢗ(ꢉ (%
ꢙꢞ$ꢊꢒ ꢎꢈ(% ꢙꢞ$ꢊ (% (ꢉꢘꢊꢉ$ꢊ$ +ꢞꢛ ꢙꢞꢛꢊ 'ꢞꢙꢗꢇꢊ!
ꢆꢗꢗꢇ('ꢆꢘ(ꢞꢉ% (ꢉ ꢝꢈ('ꢈ ꢘꢈꢊ =ꢕ=/• , ꢛꢊEꢅ(ꢛꢊ% %ꢅꢗꢗꢞꢛꢘ +ꢛꢞꢙ
ꢘꢈꢊ =ꢕ=> ꢉꢅꢙꢊꢛ(' $ꢆꢘꢆ ꢗꢛꢞ'ꢊ%%ꢞꢛ ꢏ7ꢄ,ꢐꢒ #ꢉ ꢘꢈ(% ꢙꢞ$ꢊ" ꢆ
%ꢗꢊ'(ꢆꢇ ꢚꢅ% 'ꢞꢉꢘꢛꢞꢇꢇꢊꢛ ꢏꢘꢈꢊ =ꢓ==ꢐ (% ꢛꢊEꢅ(ꢛꢊ$ ꢘꢞ -ꢊꢉꢊꢛꢆꢘꢊ
ꢘꢈꢊ ꢙꢊꢙꢞꢛ& ꢆꢉ$ #.ꢂ 'ꢞꢉꢘꢛꢞꢇ ꢚꢅ% %(-ꢉꢆꢇ%ꢒ
ꢆꢑꢆ(ꢇꢆꢚꢇꢊ ꢞꢉ ,(ꢉ ꢓ< ꢏ%ꢊꢊ
Figure 20
ꢐꢒ 8ꢞꢝꢊꢑꢊꢛ" (+ ꢘꢈꢊ
=ꢕ=/• , (% ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ Cꢙꢆ!D ꢙꢞ$ꢊ" ꢘꢈꢊꢉ ꢘꢈꢊ ꢜ#7ꢎꢌ
%(-ꢉꢆꢇ ꢙꢅ%ꢘ ꢚꢊ $ꢊꢛ(ꢑꢊ$ +ꢛꢞꢙ ꢘꢈꢊ ꢜꢃꢕ" ꢜꢃꢔ" ꢆꢉ$ ꢜꢃꢓ ꢗ(ꢉ% ꢑ(ꢆ
ꢘꢈꢊ =ꢓ== ꢚꢅ% 'ꢞꢉꢘꢛꢞꢇꢇꢊꢛꢒ Table 15 ꢗꢛꢊ%ꢊꢉꢘ% ꢘꢈꢊ ꢗꢛꢞ'ꢊ%%ꢞꢛ
%ꢘꢆꢘꢅ% ꢆꢉ$ =ꢓ== ꢆ'ꢘ(ꢑꢊ ꢞꢅꢘꢗꢅꢘ% ꢚꢆ%ꢊ$ ꢞꢉ ꢘꢈꢊ ꢜꢃꢕ" ꢜꢃꢔ" ꢆꢉ$
ꢜꢃꢓ Cꢙꢆ!D ꢙꢞ$ꢊ %ꢘꢆꢘꢅ% %(-ꢉꢆꢇ%ꢒ
ꢎꢈꢊ =ꢕ=/• , 'ꢞꢉꢘꢆ(ꢉ% ꢘꢝꢞ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ (ꢉꢗꢅꢘ%4 #7ꢎꢍ
ꢆꢉ$ 7ꢁ#ꢒ 7ꢁ# (% ꢘꢈꢊ ꢆ'ꢘ(ꢑꢊꢜꢈ(-ꢈ Cꢉꢞꢉꢜꢙꢆ%3ꢆꢚꢇꢊD (ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢜS2
ꢕ
ꢜS1
ꢜS0
ꢕ
Processor State
#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢌ'3ꢉꢞꢝꢇꢊ$-ꢊ
ꢍꢊꢆ$ #.ꢂ ,ꢞꢛꢘ
Bꢛ(ꢘꢊ #.ꢂ ,ꢞꢛꢘ
8ꢆꢇꢘ
8288 Active Output
ꢜ#7ꢎꢌ
ꢕ
ꢕ
ꢕ
ꢔ
ꢔ
ꢕ
ꢕ
ꢔ
ꢜ#ꢂꢍꢀ
ꢕ
ꢕ
ꢜ#ꢂBꢀ
ꢕ
ꢔ
7ꢞꢉꢊ
ꢜꢁꢍꢄꢀ
ꢔ
ꢕ
ꢀꢞ$ꢊ ꢌ''ꢊ%%
ꢍꢊꢆ$ ꢁꢊꢙꢞꢛ&
Bꢛ(ꢘꢊ ꢁꢊꢙꢞꢛ&
,ꢆ%%(ꢑꢊ
ꢔ
ꢔ
ꢜꢁꢍꢄꢀ
ꢜꢁBꢎꢀ
7ꢞꢉꢊ
ꢔ
ꢔ
ꢔ
ꢕ
ꢔ
ꢔ
Table 15. 8086 Processor State/8288 Bus Controller Active Output as a function of ꢜS0, ꢜS1 and ꢜS2
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
</
XR88C681
Figure 21 ꢆꢉ$ Figure 22 ꢗꢛꢊ%ꢊꢉꢘ ꢘꢈꢊ =ꢕ=/ ꢀ,ꢋ ꢁꢞ$ꢊ" ꢝꢈꢊꢉ ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ Cꢙ(ꢉD ꢆꢉ$ Cꢙꢆ!D ꢙꢞ$ꢊ%" ꢛꢊ%ꢗꢊ'ꢘ(ꢑꢊꢇ&ꢒ
ꢄꢕ ꢜ ꢄ>
ꢌꢄꢕ ꢜ ꢌꢄ>
ꢄ
)
ꢌꢕ ꢜ ꢌ>
#7ꢎꢍ
ꢜ#7ꢎꢌ
C
74LS373
ꢄ= ꢜ ꢄꢔ6
ꢌ= ꢜ ꢌꢔ6
ꢌꢄ= ꢜ ꢌꢄꢔ6
8ꢂ9ꢄ
ꢄ
)
ꢌ92
C
74LS373
ꢜꢄ27
ꢄꢎ.ꢜꢍ
ꢜ#ꢂꢍ
ꢁ.ꢜ#ꢂ
ꢜꢁ2ꢁꢍ
;''
ꢜꢍꢄ
ꢜ#ꢂB
ꢁ7.ꢜꢁ5
ꢜBꢍ
ꢜꢁ2ꢁB
8086 CPU
Figure 21. Schematic of the 8086 CPU Mode (Min Mode)
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
<>
XR88C681
ꢀ9:
ꢜꢁꢍꢄꢀ
ꢜꢁBꢎꢀ
ꢜꢁ2ꢁꢍ
ꢜꢁ2ꢁB
ꢀ9:
ꢜꢃꢕ
ꢜꢃꢔ
ꢜꢃꢓ
ꢜꢃꢕ
ꢜꢃꢔ
ꢜ#ꢂꢍꢀ
ꢜ#ꢂBꢀ
ꢜ#ꢂꢍ
ꢜꢃꢓ
ꢜ#ꢂB
ꢄ27
ꢄꢎ.ꢜꢍ
ꢌ92
ꢜ#7ꢎꢌ
#7ꢎꢍ
8288 Bus Controller
ꢄꢕ ꢜ ꢄ>
ꢌꢕ ꢜ ꢌ>
ꢌꢄꢕ ꢜ ꢌꢄ>
ꢄ
ꢀ
)
74LS373
ꢄ= ꢜ ꢄꢔ6
ꢌ= ꢜ ꢌꢔ6
ꢌꢄ= ꢜ ꢌꢄꢔ6
ꢄ
ꢀ
)
8086 CPU
ꢁ7.ꢜꢁ5
74LS373
Figure 22. Schematic of the 8086 CPU Mode (Max Mode)
8086• C Interrupt Processing
$ꢊꢘꢊꢛꢙ(ꢉꢊ ꢘꢈꢊ ꢇꢞ'ꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ ꢛꢞꢅꢘ(ꢉꢊ (ꢉ
ꢙꢊꢙꢞꢛ&ꢒ ꢃ(ꢉ'ꢊ ꢘꢈ(% C(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢑꢊ'ꢘꢞꢛD (% = ꢚ(ꢘ% ꢝ($ꢊ" ꢘꢈꢊ
=ꢕ=/ • , 'ꢆꢉ ꢆ''ꢞꢙꢙꢞ$ꢆꢘꢊ ꢅꢗ ꢘꢞ ꢓ6/ $(++ꢊꢛꢊꢉꢘ (ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢑꢊ'ꢘꢞꢛ% ꢏꢕ ꢜ ꢓ66ꢐꢒ ꢌ$$(ꢘ(ꢞꢉꢆꢇꢇ&" %(ꢉ'ꢊ ꢊꢆ'ꢈ ꢑꢊ'ꢘꢞꢛ (%
ꢙꢅꢇꢘ(ꢗꢇ(ꢊ$ ꢚ& C<D" ꢘꢈꢊ ꢅ%ꢊꢛ (% ꢊ!ꢗꢊ'ꢘꢊ$ ꢘꢞ ꢛꢊ%ꢊꢛꢑꢊ ꢘꢈꢊ +(ꢛ%ꢘ
ꢔ: ꢚ&ꢘꢊ ꢞ+ ꢙꢊꢙꢞꢛ& +ꢞꢛ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢊꢛꢑ('ꢊ
ꢍꢞꢅꢘ(ꢉꢊ%.@ꢅꢙꢗ ꢎꢆꢚꢇꢊꢒ
#+ ꢆ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ 'ꢞꢙꢗꢞꢉꢊꢉꢘ ꢛꢊEꢅ(ꢛꢊ% (ꢉꢘꢊꢛꢛꢅꢗꢘ %ꢊꢛꢑ('ꢊ +ꢛꢞꢙ
ꢘꢈꢊ ꢀ,ꢋ" (ꢘ ꢝ(ꢇꢇ ꢆ%%ꢊꢛꢘ ꢘꢈꢊ ꢀ,ꢋH% #7ꢎꢍ (ꢉꢗꢅꢘ ꢏꢚ& ꢘꢞ--ꢇ(ꢉ- (ꢘ
ꢈ(-ꢈꢐꢒ
ꢂꢉ'ꢊ ꢘꢈꢊ ꢀ,ꢋ ꢈꢆ% 'ꢞꢙꢗꢇꢊꢘꢊ$ (ꢘ% 'ꢅꢛꢛꢊꢉꢘ
(ꢉ%ꢘꢛꢅ'ꢘ(ꢞꢉ" (ꢘ ꢝ(ꢇꢇ ꢆ%%ꢊꢛꢘ ꢘꢈꢊ ꢜ#7ꢎꢌ ꢗ(ꢉ ꢏ(+ ꢞꢗꢊꢛꢆꢘ(ꢉ- (ꢉ ꢘꢈꢊ
Cꢙ(ꢉD ꢙꢞ$ꢊꢐ ꢞꢛ %ꢊꢘ ꢘꢈꢊ ꢜꢃꢕ" ꢜꢃꢔ" ꢆꢉ$ ꢜꢃꢓ ꢗ(ꢉ% ꢘꢞ CꢕD ꢏ%ꢊꢊ
Table 15ꢐꢒ #ꢉ ꢊ(ꢘꢈꢊꢛ 'ꢆ%ꢊ" ꢘꢈꢊ ꢜ#ꢌꢀ: (ꢉꢗꢅꢘ ꢞ+ ꢘꢈꢊ ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ
ꢝ(ꢇꢇ ꢚꢊ ꢆ%%ꢊꢛꢘꢊ$ꢒ ꢂꢉ'ꢊ ꢘꢈ(% ꢈꢆꢗꢗꢊꢉ%" ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ(ꢉ-
ꢗꢊꢛ(ꢗꢈꢊꢛꢆꢇ (% ꢊ!ꢗꢊ'ꢘꢊ$ ꢘꢞ ꢗꢇꢆ'ꢊ ꢆꢉ C(ꢉꢘꢊꢛꢛꢅꢗꢘ ꢑꢊ'ꢘꢞꢛD ꢚ&ꢘꢊ
ꢞꢉ ꢄꢕ ꢜ ꢄ> ꢞ+ ꢘꢈꢊ $ꢆꢘꢆ ꢚꢅ%ꢒ ꢎꢈꢊ =ꢕ=/• , ꢝ(ꢇꢇ ꢛꢊꢆ$ ꢘꢈ(% $ꢆꢘꢆ
ꢆꢉ$ ꢙꢅꢇꢘ(ꢗꢇ& ꢘꢈ(% ꢑꢆꢇꢅꢊ ꢚ& ꢘꢈꢊ ꢉꢅꢙꢚꢊꢛ < (ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ
Figure 23 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ %'ꢈꢊꢙꢆꢘ(' ꢞ+ ꢘꢈꢊ 5ꢍ==ꢀ/=ꢔ
ꢄꢋꢌꢍꢎ (ꢉꢘꢊꢛ+ꢆ'(ꢉ- ꢘꢞ ꢆ Cꢙ(ꢉD ꢁꢞ$ꢊ =ꢕ=/ ꢀ,ꢋ $ꢊꢑ('ꢊꢒ
Please note that the DUART has been configured to
operate in the Z-Mode. Therefore, the user must account
for the IEI input to the DUART deviceꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
<=
XR88C681
ꢄꢕ ꢜ ꢄ>
ꢌꢄꢕ ꢜ ꢌꢄ>
ꢄꢕ ꢜ ꢄ>
ꢌꢕ ꢜ ꢌ1
74LS373
ꢌꢕ ꢜ ꢌ1
Q
D
C
ꢌ< ꢜ ꢌ>
ꢌꢄ= ꢜ ꢌꢄꢔ6
ꢄ= ꢜ ꢄꢔ6
ꢜꢀꢃ
ꢌ$$ꢛꢊ%%
ꢄꢊ'ꢞ$ꢊꢛ
74LS373
8ꢂ9ꢄ
ꢌ= ꢜ ꢌꢔ6
Q
D
C
ꢌ92
ꢜ#ꢌꢀ:
ꢜ#7ꢎꢍ
ꢜ#7ꢎꢌ
#7ꢎꢍ
ꢜꢄ27
ꢄꢎ.ꢜꢍ
+ꢛꢞꢙ ꢈ(-ꢈꢊꢛ
ꢗꢛ(ꢞꢛ(ꢘ& $ꢊꢑ('ꢊ
#2#
ꢁ.ꢜ#ꢂ
;
''
ꢜꢍꢄ
ꢜꢁ2ꢁꢍ
ꢜꢁ2ꢁB
ꢜꢍꢄ
ꢁ7.ꢜꢁ5
ꢜBꢍ
ꢜBꢍ
8086 CPU
XR88C681
Figure 23. Schematic of the XR88C681 DUART Device Interfacing to a
“Min” Mode 8086 CPU Device
D. TIMING CONTROL BLOCK
ꢎꢈꢊ ꢎ(ꢙ(ꢉ- ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3 ꢆꢇꢇꢞꢝ% ꢘꢞ ꢘꢈꢊ ꢅ%ꢊꢛ ꢘꢞ %ꢗꢊ'(+& ꢘꢈꢊ
ꢚ(ꢘ ꢛꢆꢘꢊ% ꢘꢈꢆꢘ ꢈꢊ.%ꢈꢊ ꢝ(%ꢈꢊ% ꢘꢞ ꢘꢛꢆꢉ%ꢙ(ꢘ ꢆꢉ$ ꢛꢊ'ꢊ(ꢑꢊ $ꢆꢘꢆ ꢆꢘ
ꢊꢆ'ꢈ 'ꢈꢆꢉꢉꢊꢇꢒ ꢎꢈꢊ ꢎ(ꢙ(ꢉ- ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3 'ꢞꢉ%(%ꢘ% ꢞ+ ꢘꢈꢊ
+ꢞꢇꢇꢞꢝ(ꢉ- ꢊꢇꢊꢙꢊꢉꢘ%4
ꢁ ꢔ/ ꢚ(ꢘ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ
ꢁ < ꢜ 2!ꢘꢊꢛꢉꢆꢇ #ꢉꢗꢅꢘ ,(ꢉ% ꢏꢘꢞ 'ꢇꢞ'3 ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ%
ꢆꢉ$ ꢍꢊ'ꢊ(ꢑꢊꢛ%" $(ꢛꢊ'ꢘꢇ&ꢐ
ꢁ ꢎꢝꢞ ꢀꢇꢞ'3 ꢃꢊꢇꢊ'ꢘ ꢍꢊ-(%ꢘꢊꢛ% ꢏ1ꢓ4ꢔ ꢁꢋ5%ꢐ
ꢁ ꢂ%'(ꢇꢇꢆꢘꢞꢛ ꢀ(ꢛ'ꢅ(ꢘ
Figure 24 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ ꢚꢇꢞ'3 $(ꢆ-ꢛꢆꢙ ꢞ+ ꢘꢈꢊ ꢎ(ꢙ(ꢉ- ꢀꢞꢉꢘꢛꢞꢇ
ꢚꢇꢞ'3 +ꢞꢛ ꢘꢈꢊ 5ꢍ==ꢀ/=ꢔ $ꢊꢑ('ꢊꢒ
ꢁ *(ꢘ ꢍꢆꢘꢊ 0ꢊꢉꢊꢛꢆꢘꢞꢛ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
<ꢖ
XR88C681
#,<
ꢏꢍ5ꢀꢌꢐ
#,1
ꢏꢎ5ꢀꢌꢐ
,ꢛꢊ%ꢊꢘ ꢍꢊ-(%ꢘꢊꢛ%
ꢏꢀꢎꢋꢍ" ꢀꢎ9ꢍꢐ
1ꢓ4ꢔ
ꢁꢋ5
ꢎ!ꢀꢌ
ꢍ!ꢀꢌ
ꢎ5ꢀꢌ
ꢎ5ꢀ*
#,ꢓ
ꢄ(ꢑ($ꢊ ꢚ& ꢔ/
ꢌꢀꢍN<ꢜ/O
1ꢓ4ꢔ
ꢁꢋ5
ꢀꢞꢅꢉꢘꢊꢛ.
ꢎ(ꢙꢊꢛ
1ꢓ4ꢔ
ꢁꢋ5
ꢎ!ꢀ*
ꢍ!ꢀ*
ꢄ(ꢑ($ꢊ ꢚ& ꢔ/
1ꢓ4ꢔ
ꢁꢋ5
5ꢔ.ꢀ9:
*(ꢘ ꢍꢆꢘꢊ
0ꢊꢉꢊꢛꢆꢘꢞꢛ
ꢂ%'(ꢇꢇꢆꢘꢞꢛ
ꢀ(ꢛ'ꢅ(ꢘ
5ꢓ
#,6
ꢏꢎ5ꢀ*ꢐ
#,ꢓ
ꢏꢍ5ꢀ*ꢐ
ꢌꢀꢍN>O
Figure 24. Block Diagram of DUART Timing Control Block
2ꢆ'ꢈ ꢊꢇꢊꢙꢊꢉꢘ ꢞ+ ꢘꢈꢊ ꢎ(ꢙ(ꢉ- ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3 (% $(%'ꢅ%%ꢊ$
ꢈꢊꢛꢊ4
%(-ꢉꢆꢇ" +ꢞꢛ ꢅ%ꢊ ꢚ& ꢘꢈꢊ *(ꢘ ꢍꢆꢘꢊ 0ꢊꢉꢊꢛꢆꢘꢞꢛ" ꢆꢉ$
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛꢒ ꢌ 'ꢛ&%ꢘꢆꢇ ꢞꢛ ꢎꢎ9 %(-ꢉꢆꢇ +ꢛꢊEꢅꢊꢉ'& ꢞ+
ꢚꢊꢘꢝꢊꢊꢉ ꢓ ꢁ8I ꢆꢉ$ < ꢁ8I (% ꢛꢊEꢅ(ꢛꢊ$ +ꢞꢛ ꢗꢛꢞꢗꢊꢛ
ꢞꢗꢊꢛꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎꢒ 8ꢞꢝꢊꢑꢊꢛ" ꢆ 'ꢛ&%ꢘꢆꢇ ꢞꢛ ꢎꢎ9 %(-ꢉꢆꢇ
+ꢛꢊEꢅꢊꢉ'& ꢞ+ 1ꢒ/=/< ꢁ8I (% ꢛꢊEꢅ(ꢛꢊ$ +ꢞꢛ ꢘꢈꢊ -ꢊꢉꢊꢛꢆꢘ(ꢞꢉ ꢞ+
%ꢘꢆꢉ$ꢆꢛ$ ꢚ(ꢘ ꢛꢆꢘꢊ% ꢚ& ꢘꢈꢊ *(ꢘ ꢍꢆꢘꢊ 0ꢊꢉꢊꢛꢆꢘꢞꢛ ꢏꢃꢊꢊ
D.1 Oscillator Circuit:
ꢌ 'ꢛ&%ꢘꢆꢇ ꢞ%'(ꢇꢇꢆꢘꢞꢛ (% ꢘ&ꢗ('ꢆꢇꢇ& 'ꢞꢉꢉꢊ'ꢘꢊ$ ꢊ!ꢘꢊꢛꢉꢆꢇꢇ&
ꢆ'ꢛꢞ%% ꢘꢈꢊ 5ꢔ.ꢀ9: ꢆꢉ$ 5ꢓ ꢗ(ꢉ%ꢒ ꢎꢈꢊ ꢂ%'(ꢇꢇꢆꢘꢞꢛ ꢀ(ꢛ'ꢅ(ꢘ
ꢏꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ 'ꢈ(ꢗꢐ +ꢅꢉ'ꢘ(ꢞꢉ% ꢆ% ꢘꢈꢊ ꢇꢞꢆ$ +ꢞꢛ ꢘꢈꢊ ꢛꢊ%ꢞꢉꢆꢉꢘ
ꢏ'ꢛ&%ꢘꢆꢇꢐ ꢞ%'(ꢇꢇꢆꢘꢞꢛ" ꢆꢉ$ ꢚꢅ++ꢊꢛ% ꢘꢈꢊ ꢛꢊ%ꢅꢇꢘ(ꢉ- ꢞ%'(ꢇꢇꢆꢘ(ꢉ-
Table 18ꢐꢒ
%'ꢈꢊꢙꢆꢘ(' +ꢞꢛ ꢘꢈꢊ 5ꢎꢌ9 ꢂ%'(ꢇꢇꢆꢘꢞꢛ '(ꢛ'ꢅ(ꢘꢛ&ꢒ
Figure 25 ꢗꢛꢊ%ꢊꢉꢘ%
ꢆ
ꢛꢊ'ꢞꢙꢙꢊꢉ$ꢊ$
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
6ꢕ
XR88C681
ꢀꢔ4 ꢔꢕꢗ A ꢏꢃꢘꢛꢆ& Q 6ꢗ ꢐ
ꢀꢓ4 ꢔꢕꢗ A ꢏꢃꢘꢛꢆ& Q 6ꢗ ꢐ
ꢍꢔ4 ꢔꢕꢕꢞꢈꢙ
ꢍꢓ4 ꢔꢕꢕꢞꢈꢙ
ꢍꢔ
5ꢔ
ꢀꢔ
ꢀꢓ
XR88C681
ꢍꢓ
5ꢓ
1ꢒ/=/<ꢁ8I
,ꢆꢛꢆꢇꢇꢊꢇ ꢍꢊ%ꢞꢉꢆꢉꢘ ꢀꢛ&%ꢘꢆꢇ
Figure 25. A Recommended Schematic for the XTAL Oscillator Circuitry
Note: The user also has an option to drive the Oscillator Circuit with a TTL input signal, in lieu of using a crystal oscillator. If this
approach is used, the TTL must be driven into the X1/CLK pin, and the X2 pin must be left floating.
#+ ꢘꢈꢊ ꢅ%ꢊꢛ $ꢊ%(ꢛꢊ% ꢘꢞ ꢛꢅꢉ ꢉꢅꢙꢊꢛꢞꢅ% ꢄꢋꢌꢍꢎ% +ꢛꢞꢙ ꢆ %(ꢉ-ꢇꢊ 'ꢛ&%ꢘꢆꢇ ꢞ%'(ꢇꢇꢆꢘꢞꢛ" Figure 26 ꢗꢛꢊ%ꢊꢉꢘ% ꢆꢉ ꢆꢗꢗꢛꢞꢆ'ꢈ ꢆꢉ$ ꢘꢈꢊ
ꢉꢊ'ꢊ%%ꢆꢛ& '(ꢛ'ꢅ(ꢘꢛ& ꢘꢞ ꢆ''ꢞꢙꢗꢇ(%ꢈ ꢘꢈ(% ꢞꢚMꢊ'ꢘ(ꢑꢊꢒ
XR88C681
5ꢔ
5ꢓ
Gꢔ
ꢎꢞ 5ꢔ (ꢉꢗꢅꢘ% ꢞ+
ꢞꢘꢈꢊꢛ ꢄꢋꢌꢍꢎ%
1ꢒ/=<ꢁ8I
><8ꢀꢔ<
Figure 26. A Recommended Schematic to Drive Multiple DUARTs From the Same Crystal Oscillator.
Note: Theuser is urgednottouse the74LS14SchmittTriggerInverterin lieu ofthe74HC14device. Theinputofthe74LS14tendsto
load down the oscillating signal from the DUART, to the point that the Schmitt Trigger inverter can no longer change state or
respond to the oscillator signal.
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
6ꢔ
XR88C681
D.2 Bit Rate Generator
'ꢇꢞ'3 +ꢛꢊEꢅꢊꢉ'(ꢊ% ꢞꢅꢘꢗꢅꢘ +ꢛꢞꢙ ꢘꢈꢊ *ꢍ0 ꢆꢛꢊ ꢆꢘ ꢔ/ ꢘ(ꢙꢊ%
ꢘꢈꢊ%ꢊ ꢛꢆꢘꢊ%ꢒ
ꢎꢈꢊ *ꢍ0 ꢏ*(ꢘ ꢍꢆꢘꢊ 0ꢊꢉꢊꢛꢆꢘꢞꢛꢐ ꢆ''ꢊꢗꢘ% ꢘꢈꢊ ꢘ(ꢙ(ꢉ- ꢞꢅꢘꢗꢅꢘ
ꢞ+ ꢘꢈꢊ ꢂ%'(ꢇꢇꢆꢘꢞꢛ ꢀ(ꢛ'ꢅ(ꢘ ꢆꢉ$ -ꢊꢉꢊꢛꢆꢘꢊ ꢘꢈꢊ 'ꢇꢞ'3 %(-ꢉꢆꢇ +ꢞꢛ
ꢓ1 'ꢞꢙꢙꢞꢉꢇ& ꢅ%ꢊ$ $ꢆꢘꢆ 'ꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉ ꢚ(ꢘ ꢛꢆꢘꢊ% ꢛꢆꢉ-(ꢉ-
+ꢛꢞꢙ 6ꢕ ꢚꢗ% ꢅꢗ ꢘꢞ ꢔꢔ6ꢒꢓ3ꢚꢗ%ꢒ Please note that the BRG
will only generate these standard bit rates if the Oscillator
Circuit is running at 3.6864 MHzꢒ ꢌ$$(ꢘ(ꢞꢉꢆꢇꢇ&" ꢘꢈꢊ ꢆ'ꢘꢅꢆꢇ
ꢎꢈꢊ ꢅ%ꢊꢛ 'ꢆꢉ %ꢊꢇꢊ'ꢘ ꢞꢉꢊ ꢞ+ ꢘꢝꢞ $(++ꢊꢛꢊꢉꢘ %ꢊꢘ% ꢞ+ ꢚ(ꢘ ꢛꢆꢘꢊ%" ꢘꢞ
ꢚꢊ -ꢊꢉꢊꢛꢆꢘꢊ$ +ꢛꢞꢙ ꢘꢈꢊ *ꢍ0ꢒ ꢎꢈ(% %ꢊꢇꢊ'ꢘ(ꢞꢉ (% ꢙꢆ$ꢊ ꢚ&
%ꢊꢘꢘ(ꢉ- ꢞꢛ 'ꢇꢊꢆꢛ(ꢉ- ꢌꢀꢍN>Oꢒ ꢌ ꢇ(%ꢘ(ꢉ- ꢞ+ ꢘꢈꢊ%ꢊ %ꢊꢘ% ꢞ+ *(ꢘ
ꢍꢆꢘꢊ%" +ꢛꢞꢙ ꢘꢈꢊ *ꢍ0" (% ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ ꢘꢈꢊ $(%'ꢅ%%(ꢞꢉ ꢞ+ ꢘꢈꢊ
ꢀꢇꢞ'3 ꢃꢊꢇꢊ'ꢘ ꢍꢊ-(%ꢘꢊꢛ% ꢏꢀꢃꢍ%ꢐ (ꢉ Section D.5ꢒ ꢌ ꢚꢇꢞ'3
$(ꢆ-ꢛꢆꢙ ꢞ+ ꢘꢈꢊ *ꢍ0 '(ꢛ'ꢅ(ꢘꢛ& (% ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ Figure 27ꢒ
ꢀꢃꢍꢌN>4<O
ꢍ5ꢀꢌ
ꢎ5ꢀꢌ
ꢍ5ꢀ*
1ꢓ4ꢔ ꢁꢋ5
ꢀꢃꢍꢌN14ꢕO
1ꢓ4ꢔ ꢁꢋ5
ꢌꢀꢍN>O
5ꢔ.ꢀ9:
5ꢓ
ꢂ%'(ꢇꢇꢆꢘꢞꢛ
ꢀ(ꢛ'ꢅ(ꢘ
*(ꢘ ꢍꢆꢘꢊ 0ꢊꢉꢊꢛꢆꢘꢞꢛ
ꢀꢈꢆꢉꢉꢊꢇ% ꢌ ꢆꢉ$ *
ꢀꢃꢍ*N>4<O
1ꢓ4ꢔ ꢁꢋ5
ꢀꢃꢍ*N14ꢕO
ꢎ5ꢀ*
1ꢓ4ꢔ ꢁꢋ5
Figure 27. Block Diagram of the Bit Rate Generator portion of the Timing Control Block
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
6ꢓ
XR88C681
D.3 Counter/Timer
ꢘ(ꢙ(ꢉ- %ꢞꢅꢛ'ꢊ% +ꢞꢛ ꢘꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ 'ꢆꢉ ꢚꢊ ꢙꢆ$ꢊ ꢚ&
ꢝꢛ(ꢘ(ꢉ- ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ $ꢆꢘꢆ ꢘꢞ ꢌꢀꢍN/4<O ꢏꢌꢅ!(ꢇ(ꢆꢛ& ꢀꢞꢉꢘꢛꢞꢇ
ꢍꢊ-(%ꢘꢊꢛ ꢚ(ꢘ% / ꢘꢈꢛꢞꢅ-ꢈ <ꢐꢒ ,ꢇꢊꢆ%ꢊ %ꢊꢊ Table 16 +ꢞꢛ ꢘꢈꢊ
ꢛꢊꢇꢆꢘ(ꢞꢉ%ꢈ(ꢗ ꢚꢊꢘꢝꢊꢊꢉ ꢘꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢙꢞ$ꢊ" ꢘꢈꢊ
ꢎ(ꢙ(ꢉ- ꢃꢞꢅꢛ'ꢊ ꢆꢉ$ ꢌꢀꢍN/4<Oꢒ ꢎꢈꢊ ꢀ.ꢎ ꢞꢅꢘꢗꢅꢘ (% ꢆꢑꢆ(ꢇꢆꢚꢇꢊ
ꢘꢞ ꢘꢈꢊ ꢀꢇꢞ'3 ꢃꢊꢇꢊ'ꢘ ꢍꢊ-(%ꢘꢊꢛ% +ꢞꢛ ꢅ%ꢊ ꢆ% ꢆ ꢗꢛꢞ-ꢛꢆꢙꢙꢆꢚꢇꢊ
ꢚ(ꢘ ꢛꢆꢘꢊ -ꢊꢉꢊꢛꢆꢘꢞꢛ +ꢞꢛ ꢚꢞꢘꢈ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ% ꢆꢉ$ ꢍꢊ'ꢊ(ꢑꢊꢛ%ꢒ
ꢎꢈꢊ ꢎ(ꢙ(ꢉ- ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3 ꢆꢇ%ꢞ 'ꢞꢉꢘꢆ(ꢉ% ꢆ ꢔ/ ꢚ(ꢘ
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢏꢀ.ꢎꢐꢒ ꢎꢈꢊ ꢀ.ꢎ (% ꢆ ꢗꢛꢞ-ꢛꢆꢙꢙꢆꢚꢇꢊ ꢔ/ ꢚ(ꢘ
$ꢞꢝꢉꢜ'ꢞꢅꢉꢘꢊꢛ ꢝꢈ('ꢈ 'ꢆꢉ ꢅ%ꢊ ꢞꢉꢊ ꢞ+ %ꢊꢑꢊꢛꢆꢇ ꢘ(ꢙ(ꢉ-
%ꢞꢅꢛ'ꢊ% ꢆ% (ꢘ% (ꢉꢗꢅꢘꢒ Figure 28 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ ꢚꢇꢞ'3 $(ꢆ-ꢛꢆꢙ
ꢞ+ ꢘꢈꢊ '(ꢛ'ꢅ(ꢘꢛ& %ꢅꢛꢛꢞꢅꢉ$(ꢉ- ꢘꢈꢊ ꢀ.ꢎꢒ ꢎꢈꢊ %ꢊꢇꢊ'ꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ%ꢊ
ꢂ%'(ꢇꢇꢆꢘꢞꢛ
ꢀ(ꢛ'ꢅ(ꢘ
,ꢛꢊ%ꢊꢘ ꢍꢊ-(%ꢘꢊꢛ%
ꢏꢀꢎꢋꢍ" ꢀꢎ9ꢍꢐ
ꢄ(ꢑ($ꢊ ꢚ& ꢔ/
ꢘꢞ 1ꢓ4ꢔ ꢁꢋ5%
#,ꢓ
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ
ꢄ(ꢑ($ꢊ ꢚ& ꢔ/
ꢀ.ꢎFꢍꢄG
ꢏꢂ,1ꢐ
ꢎ5ꢀꢌ
ꢎ5ꢀ*
ꢌꢀꢍN<ꢜ/O
Figure 28. A Block Diagram of the Circuitry Associated with the
Counter/Timer
Bit 6
Bit 5
Bit 4
C/T Mode
ꢀꢞꢅꢉꢘꢊꢛ
ꢀꢞꢅꢉꢘꢊꢛ
ꢀꢞꢅꢉꢘꢊꢛ
ꢀꢞꢅꢉꢘꢊꢛ
ꢎ(ꢙꢊꢛ
Timing Source
ꢕ
ꢕ
ꢕ
ꢕ
ꢔ
ꢔ
ꢔ
ꢔ
ꢕ
ꢕ
ꢔ
ꢔ
ꢕ
ꢕ
ꢔ
ꢔ
ꢕ
ꢔ
ꢕ
ꢔ
ꢕ
ꢔ
ꢕ
ꢔ
2!ꢘꢊꢛꢉꢆꢇ #ꢉꢗꢅꢘ ꢜ #,ꢓ
ꢎ5ꢀꢌ ꢔ5 ꢜ ꢀꢇꢞ'3 ꢞ+ ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ
ꢎ5ꢀ* ꢔ5 ꢜ ꢀꢇꢞ'3 ꢞ+ ꢀꢈꢆꢉꢉꢊꢇ * ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ
5ꢔ.ꢀ9: #ꢉꢗꢅꢘ ꢄ(ꢑ($ꢊ$ ꢚ& ꢔ/
2!ꢘꢊꢛꢉꢆꢇ #ꢉꢗꢅꢘ ꢜ #,ꢓ
ꢎ(ꢙꢊꢛ
2!ꢘꢊꢛꢉꢆꢇ #ꢉꢗꢅꢘ ꢜ #,ꢓ" ꢄ(ꢑ($ꢊ$ ꢚ& ꢔ/
5ꢔ.ꢀ9: #ꢉꢗꢅꢘ
ꢎ(ꢙꢊꢛ
ꢎ(ꢙꢊꢛ
5ꢔ.ꢀ9: #ꢉꢗꢅꢘ ꢄ(ꢑ($ꢊ$ ꢚ& ꢔ/
Table 16. ACR[6:4] Bit Field Definition - C/T
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
61
XR88C681
D.3.1 Timer Mode:
(ꢉꢘꢊꢛꢛꢅꢗꢘ -ꢊꢉꢊꢛꢆꢘꢞꢛ" (+ ꢘꢈꢊ 'ꢞꢉ$(ꢘ(ꢞꢉ (% ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ
-ꢊꢉꢊꢛꢆꢘꢊ ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢑ(ꢆ ꢘꢈꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢙꢆ%3 ꢛꢊ-(%ꢘꢊꢛ
ꢏ#ꢁꢍꢐꢒ ꢎꢈꢊ #ꢃꢍN1O 'ꢆꢉ ꢚꢊ 'ꢇꢊꢆꢛꢊ$ ꢚ& (%%ꢅ(ꢉ- ꢘꢈꢊ
ꢆ$$ꢛꢊ%%ꢜꢘꢛ(--ꢊꢛꢊ$ Cꢃꢎꢂ, ꢀꢂꢋ7ꢎ2ꢍD 'ꢞꢙꢙꢆꢉ$ ꢏꢃꢊꢊ
Table 1ꢐꢒ #ꢉ ꢘꢈꢊ ꢎ#ꢁ2ꢍ ꢙꢞ$ꢊ" ꢈꢞꢝꢊꢑꢊꢛ" ꢘꢈꢊ 'ꢞꢙꢙꢆꢉ$
$ꢞꢊ% ꢉꢞꢘ ꢆ'ꢘꢅꢆꢇꢇ& %ꢘꢞꢗ ꢘꢈꢊ ꢀ.ꢎꢒ
Please note that of the two C/T Modes, the Timer Mode is
the only mode which is relevant to the function of Bit Rate
Selection. 8ꢞꢝꢊꢑꢊꢛ" +ꢞꢛ 'ꢞꢙꢗꢇꢊꢘꢊꢉꢊ%%" ꢘꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ
ꢁꢞ$ꢊ (% ꢆꢇ%ꢞ $(%'ꢅ%%ꢊ$ ꢈꢊꢛꢊꢒ
#ꢉ ꢘꢈꢊ ꢎ(ꢙꢊꢛ ꢙꢞ$ꢊ" ꢘꢈꢊ ꢀ.ꢎ ꢆ'ꢘ% ꢆ% ꢆ ꢗꢛꢞ-ꢛꢆꢙꢙꢆꢚꢇꢊ
$(ꢑ($ꢊꢛ ꢆꢉ$ -ꢊꢉꢊꢛꢆꢘꢊ% ꢆ %Eꢅꢆꢛꢊ ꢝꢆꢑꢊ ꢝꢈꢞ%ꢊ ꢗꢊꢛ(ꢞ$ (%
ꢘꢝ('ꢊ ꢘꢈꢊ ꢑꢆꢇꢅꢊ ꢏ(ꢉ 'ꢇꢞ'3 ꢗꢊꢛ(ꢞ$%ꢐ ꢞ+ ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢍꢊ-(%ꢘꢊꢛ%" ꢀꢎꢋꢍ ꢆꢉ$ ꢀꢎ9ꢍꢒ ꢎꢈꢊ ꢀ.ꢎ 'ꢆꢉ
ꢚꢊ ꢅ%ꢊ$ ꢆ% ꢆ ꢗꢛꢞ-ꢛꢆꢙꢙꢆꢚꢇꢊ ꢚ(ꢘ ꢛꢆꢘꢊ -ꢊꢉꢊꢛꢆꢘꢞꢛ (ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ
ꢗꢛꢞ$ꢅ'ꢊ ꢆ ꢔ/5 'ꢇꢞ'3 +ꢞꢛ ꢆꢉ& ꢚ(ꢘ ꢛꢆꢘꢊ ꢉꢞꢘ ꢗꢛꢞꢑ($ꢊ$ ꢚ& ꢘꢈꢊ
*ꢍ0ꢒ ꢎꢈꢊ %Eꢅꢆꢛꢊꢜꢝꢆꢑꢊ" ꢞꢛ(-(ꢉꢆꢘ(ꢉ- +ꢛꢞꢙ ꢘꢈꢊ ꢀ.ꢎ (%
ꢞꢅꢘꢗꢅꢘ ꢞꢉ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ" ꢂ,1ꢒ
D.3.2 COUNTER MODE
#ꢉ ꢘꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ ꢁꢞ$ꢊ" ꢘꢈꢊ ꢀ.ꢎ 'ꢞꢅꢉꢘ% $ꢞꢝꢉ ꢘꢈꢊ ꢉꢅꢙꢚꢊꢛ ꢞ+
ꢗꢅꢇ%ꢊ% ꢝꢛ(ꢘꢘꢊꢉ (ꢉꢘꢞ ꢀꢎꢋꢍ.ꢀꢎ9ꢍ" ꢚꢊ-(ꢉꢉ(ꢉ- ꢆꢘ ꢘꢈꢊ ꢛꢊ'ꢊ(ꢗꢘ
ꢞ+
ꢀꢂꢋ7ꢎ2ꢍ.ꢍ2ꢌꢄG %ꢘꢆꢘꢅ% ꢚ(ꢘ ꢏ#ꢃꢍN1Oꢐ (% %ꢊꢘ ꢅꢗꢞꢉ
ꢛꢊꢆ'ꢈ(ꢉ- ꢘꢈꢊ 'ꢞꢅꢉꢘ ꢞ+ ꢕꢕꢕꢕ ꢒ ꢎꢈꢊ ꢀ.ꢎ ꢝ(ꢇꢇ 'ꢞꢉꢘ(ꢉꢅꢊ ꢘꢞ
ꢆ
Cꢃꢎꢌꢍꢎ ꢀꢂꢋ7ꢎ2ꢍD 'ꢞꢙꢙꢆꢉ$ꢒ
ꢎꢈꢊ
ꢔ/
'ꢞꢅꢉꢘ ꢗꢆ%ꢘ ꢘꢈꢊ ꢕꢕꢕꢕ ꢆꢉ$ ꢅꢉ$ꢊꢛ+ꢇꢞꢝ ꢏꢝ(ꢘꢈ ꢘꢈꢊ ꢉꢊ!ꢘ 'ꢞꢅꢉꢘ
ꢔ/
ꢚꢊ(ꢉ- ꢐ ꢅꢉꢘ(ꢇ (ꢘ (% %ꢘꢞꢗꢗꢊ$ ꢚ& ꢘꢈꢊ ꢀ,ꢋ ꢑ(ꢆ ꢆ Cꢃꢎꢂ,
#+ ꢘꢈꢊ ꢀ.ꢎ (% ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈꢊ ꢎ(ꢙꢊꢛ ꢙꢞ$ꢊ"
ꢘꢈꢊ +ꢛꢊEꢅꢊꢉ'& ꢞ+ ꢘꢈꢊ ꢛꢊ%ꢅꢇꢘ(ꢉ- ꢀ.ꢎ %Eꢅꢆꢛꢊ ꢝꢆꢑꢊ 'ꢆꢉ ꢚꢊ
ꢊ!ꢗꢛꢊ%%ꢊ$ ꢆ% +ꢞꢇꢇꢞꢝ%4
ꢔ/
ꢀꢂꢋ7ꢎ2ꢍD 'ꢞꢙꢙꢆꢉ$ꢒ #+ ꢂ,1 (% ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ ꢚꢊ ꢘꢈꢊ
ꢞꢅꢘꢗꢅꢘ ꢞ+ ꢘꢈꢊ ꢀ.ꢎ" ꢘꢈꢊ ꢞꢅꢘꢗꢅꢘ ꢝ(ꢇꢇ ꢛꢊꢙꢆ(ꢉ ꢈ(-ꢈ ꢅꢉꢘ(ꢇ ꢘꢈꢊ
ꢘꢊꢛꢙ(ꢉꢆꢇ 'ꢞꢅꢉꢘ (% ꢛꢊꢆ'ꢈꢊ$" ꢆꢘ ꢝꢈ('ꢈ ꢘ(ꢙꢊ ꢘꢈꢊ ꢞꢅꢘꢗꢅꢘ -ꢞꢊ%
ꢇꢞꢝꢒ #ꢘ ꢘꢈꢊꢉ ꢛꢊꢘꢅꢛꢉ% ꢘꢞ ꢘꢈꢊ ꢈ(-ꢈ %ꢘꢆꢘꢊ ꢆꢉ$ #ꢃꢍN1O (% 'ꢇꢊꢆꢛꢊ$
ꢝꢈꢊꢉ ꢘꢈꢊ ꢀ.ꢎ (% %ꢘꢞꢗꢗꢊ$ ꢏꢑ(ꢆ ꢘꢈꢊ Cꢃꢎꢂ, ꢀꢂꢋ7ꢎ2ꢍD
'ꢞꢙꢙꢆꢉ$ꢐꢒ ꢌ Cꢃꢎꢌꢍꢎ ꢀꢂꢋ7ꢎ2ꢍD 'ꢞꢙꢙꢆꢉ$ ꢝꢈ(ꢇꢊ ꢘꢈꢊ
'ꢞꢅꢉꢘꢊꢛ (% ꢛꢅꢉꢉ(ꢉ- ꢛꢊ%ꢘꢆꢛꢘ% ꢘꢈꢊ 'ꢞꢅꢉꢘꢊꢛ ꢝ(ꢘꢈ ꢘꢈꢊ ꢑꢆꢇꢅꢊ% (ꢉ
ꢀꢎꢋꢍ.ꢀꢎ9ꢍꢒ ꢎꢈꢊ ꢀ,ꢋ ꢙꢆ& 'ꢈꢆꢉ-ꢊ ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+
ꢀꢎꢋꢍ ꢞꢛ ꢀꢎ9ꢍ ꢆꢘ ꢆꢉ& ꢘ(ꢙꢊ ꢚꢅꢘ ꢘꢈꢊ ꢉꢊꢝ 'ꢞꢅꢉꢘ ꢘꢆ3ꢊ% ꢊ++ꢊ'ꢘ
ꢞꢉꢇ& ꢞꢉ ꢆ+ꢘꢊꢛ ꢘꢈꢊ %ꢅꢚ%ꢊEꢅꢊꢉꢘ ꢃꢎꢌꢍꢎ ꢀꢂꢋ7ꢎ2ꢍ
'ꢞꢙꢙꢆꢉ$ꢒ #+ ꢉꢊꢝ ꢑꢆꢇꢅꢊ% ꢆꢛꢊ ꢉꢞꢘ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢈꢊ
ꢗꢛꢊꢑ(ꢞꢅ% ꢑꢆꢇꢅꢊ% ꢆꢛꢊ ꢗꢛꢊ%ꢊꢛꢑꢊ$ ꢆꢉ$ ꢅ%ꢊ$ +ꢞꢛ ꢘꢈꢊ ꢉꢊ!ꢘ
'&'ꢇꢊꢒ
ꢀ.ꢎ ꢂꢅꢘꢗꢅꢘ ꢛꢊEꢅꢊꢉ'& J
ꢛꢊEꢅꢊꢉ'& ꢞ+ ꢃꢊꢇꢊ'ꢘꢊ$ ꢎ(ꢙ(ꢉ- ꢃꢞꢅꢛ'ꢊ
ꢓRꢏNꢀꢎꢋꢍORꢓ=
+ Nꢀꢎ9ꢍO ꢐ
Bꢈꢊꢛꢊ4 NꢀꢎꢋꢍO J ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ ꢀꢎꢋꢍ ꢛꢊ-(%ꢘꢊꢛ (ꢉ
$ꢊ'(ꢙꢆꢇ +ꢞꢛꢙ
NꢀꢎꢋꢍO J ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ ꢀꢎ9ꢍ ꢛꢊ-(%ꢘꢊꢛ (ꢉ
$ꢊ'(ꢙꢆꢇ +ꢞꢛꢙ
ꢃ(ꢉ'ꢊ ꢘꢈꢊ ꢀ.ꢎ ꢂꢅꢘꢗꢅꢘ (% ꢈꢆꢉ$ꢇꢊ$ ꢆ% ꢆ ꢔ/5 'ꢇꢞ'3 %(-ꢉꢆꢇ ꢚ&
ꢘꢈꢊ ꢄꢋꢌꢍꢎ '(ꢛ'ꢅ(ꢘꢛ&" ꢘꢈꢊ ꢛꢊ%ꢅꢇꢘ(ꢉ- ꢚ(ꢘ ꢛꢆꢘꢊ (% ꢔ.ꢔ/ ꢘꢈꢊ
+ꢛꢊEꢅꢊꢉ'& ꢞ+ ꢘꢈꢊ ꢀ.ꢎ ꢂꢅꢘꢗꢅꢘ %(-ꢉꢆꢇꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢘꢈꢊ ꢚ(ꢘ
ꢛꢆꢘꢊ" $ꢊꢛ(ꢑꢊ$ +ꢛꢞꢙ ꢘꢈꢊ ꢀ.ꢎ 'ꢆꢉ ꢚꢊ ꢊ!ꢗꢛꢊ%%ꢊ$ ꢆ% +ꢞꢇꢇꢞꢝ%4
D.4 External Inputs
ꢎꢈꢊ ꢄꢋꢌꢍꢎ ꢆꢇꢇꢞꢝ% +ꢞꢛ %ꢞꢙꢊ ꢞ+ ꢘꢈꢊ #ꢉꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ% ꢏ#,ꢓ ꢜ
#,6ꢐ ꢘꢞ ꢚꢊ ꢅ%ꢊ$ ꢆ% $(ꢛꢊ'ꢘ ꢊ!ꢘꢊꢛꢉꢆꢇ (ꢉꢗꢅꢘ% ꢘꢞ ꢘꢈꢊ ꢎ(ꢙ(ꢉ-
ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3 ꢆ% ꢘ(ꢙ(ꢉ- %ꢞꢅꢛ'ꢊ% +ꢞꢛ ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ% ꢆꢉ$
ꢍꢊ'ꢊ(ꢑꢊꢛ% ꢞ+ ꢚꢞꢘꢈ 'ꢈꢆꢉꢉꢊꢇ%ꢒ Please note that the user can
specify whether a clock signal, applied to one of these
external inputs, is a 1X or a 16X clock signal; via the Clock
Select Registers ꢏ%ꢊꢊ Section D.5ꢐ. ꢞꢛ ꢆ ꢙꢞꢛꢊ $ꢊꢘꢆ(ꢇꢊ$
$(%'ꢅ%%(ꢞꢉ ꢞꢉ ꢘꢈꢊ #ꢉꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ% ꢆꢉ$ ꢘꢈꢊ(ꢛ +ꢅꢉ'ꢘ(ꢞꢉ"
ꢗꢇꢊꢆ%ꢊ %ꢊꢊ Section Eꢒ
*(ꢘ ꢍꢆꢘꢊ J
ꢛꢊEꢅꢊꢉ'& ꢞ+ ꢃꢊꢇꢊ'ꢘꢊ$ ꢎ(ꢙ(ꢉ- ꢃꢞꢅꢛ'ꢊ
1ꢓRꢏNꢀꢎꢋꢍORꢓ=
+ Nꢀꢎ9ꢍO ꢐ
ꢎꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ ꢀꢎꢋꢍ ꢆꢉ$ ꢀꢎ9ꢍ ꢛꢊ-(%ꢘꢊꢛ% ꢙꢆ& ꢚꢊ
'ꢈꢆꢉ-ꢊ$ ꢆꢘ ꢆꢉ& ꢘ(ꢙꢊ" ꢚꢅꢘ ꢝ(ꢇꢇ ꢞꢉꢇ& ꢚꢊ-(ꢉ ꢘꢞ ꢘꢆ3ꢊ ꢊ++ꢊ'ꢘ ꢆꢘ
ꢘꢈꢊ ꢉꢊ!ꢘ ꢈꢆꢇ+ '&'ꢇꢊ ꢞ+ ꢘꢈꢊ %Eꢅꢆꢛꢊ ꢝꢆꢑꢊꢒ ꢎꢈꢊ ꢀ.ꢎ ꢚꢊ-(ꢉ%
ꢞꢗꢊꢛꢆꢘ(ꢞꢉ ꢅ%(ꢉ- ꢘꢈꢊ ꢑꢆꢇꢅꢊ% (ꢉ ꢀꢎꢋꢍ.ꢀꢎ9ꢍ ꢅꢗꢞꢉ ꢛꢊ'ꢊ(ꢗꢘ ꢞ+
ꢘꢈꢊ ꢌ$$ꢛꢊ%%ꢜꢎꢛ(--ꢊꢛ Cꢃꢎꢌꢍꢎ ꢀꢂꢋ7ꢎ2ꢍD 'ꢞꢙꢙꢆꢉ$ ꢏꢃꢊꢊ
Table 1ꢐꢒ
D.5 Clock Select Registers, CSRA and CSRB
ꢎꢈꢊ ꢀ.ꢎ ꢘꢈꢊꢉ ꢛꢅꢉ% 'ꢞꢉꢘ(ꢉꢅꢞꢅ%ꢇ&ꢒ ꢌ %ꢅꢚ%ꢊEꢅꢊꢉꢘ Cꢃꢎꢌꢍꢎ
ꢀꢂꢋ7ꢎ2ꢍD 'ꢞꢙꢙꢆꢉ$ 'ꢆꢅ%ꢊ% ꢘꢈꢊ ꢀ.ꢎ ꢘꢞ ꢘꢊꢛꢙ(ꢉꢆꢘꢊ ꢘꢈꢊ
'ꢅꢛꢛꢊꢉꢘ ꢘ(ꢙ(ꢉ- '&'ꢇꢊ ꢆꢉ$ ꢚꢊ-(ꢉ ꢆ ꢉꢊꢝ ꢘ(ꢙ(ꢉ- '&'ꢇꢊ ꢅ%(ꢉ-
ꢘꢈꢊ 'ꢅꢛꢛꢊꢉꢘ ꢑꢆꢇꢅꢊ% %ꢘꢞꢛꢊ$ (ꢉ ꢀꢎꢋꢍ ꢆꢉ$ ꢀꢎ9ꢍꢒ ꢎꢈꢊ
ꢀꢂꢋ7ꢎ2ꢍ ꢍ2ꢌꢄG %ꢘꢆꢘꢅ% ꢚ(ꢘ" (ꢉ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢘꢆꢘꢅ%
ꢍꢊ-(%ꢘꢊꢛ ꢏ#ꢃꢍN1Oꢐ" (% %ꢊꢘ ꢞꢉ'ꢊ ꢊꢆ'ꢈ '&'ꢇꢊ ꢞ+ ꢘꢈꢊ %Eꢅꢆꢛꢊ
ꢝꢆꢑꢊꢒ ꢎꢈ(% ꢆꢇꢇꢞꢝ% ꢘꢈꢊ ꢅ%ꢊ ꢞ+ ꢘꢈꢊ ꢀ.ꢎ ꢆ% ꢆ ꢗꢊꢛ(ꢞ$('
#ꢉ Figure 24" ꢘꢈꢊ ꢀꢇꢞ'3 ꢃꢊꢇꢊ'ꢘ ꢍꢊ-(%ꢘꢊꢛ% ꢆꢛꢊ ꢘꢈꢊ 1ꢓ4ꢔ
ꢁꢋ5H%ꢒ ꢎꢈꢊ ꢀꢇꢞ'3 ꢃꢊꢇꢊ'ꢘ ꢍꢊ-(%ꢘꢊꢛ% ꢆꢛꢊ ꢘꢈꢊ ꢙꢊꢆꢉ% ꢘꢈꢆꢘ
ꢘꢈꢊ ꢅ%ꢊꢛ 'ꢆꢉ %ꢊꢇꢊ'ꢘ ꢝꢈ('ꢈ 'ꢇꢞ'3 %(-ꢉꢆꢇ% ꢝ(ꢇꢇ $ꢛ(ꢑꢊ ꢘꢈꢊ
ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ% ꢆꢉ$ ꢍꢊ'ꢊ(ꢑꢊꢛ% ꢞ+ ꢚꢞꢘꢈ 'ꢈꢆꢉꢉꢊꢇ%ꢒ ꢎꢈꢊ ꢀꢃꢍ%
ꢆꢇꢇꢞꢝ ꢘꢈꢊ ꢅ%ꢊꢛ ꢘꢞ %ꢊꢇꢊ'ꢘ ꢘꢈꢊ ꢓ1 $(++ꢊꢛꢊꢉꢘ %ꢘꢆꢉ$ꢆꢛ$ ꢚ(ꢘ ꢛꢆꢘꢊ%
+ꢛꢞꢙ ꢘꢈꢊ *ꢍ0" ꢘꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢞꢅꢘꢗꢅꢘ" ꢞꢛ ꢘꢞ ꢅ%ꢊ ꢆꢉ
ꢊ!ꢘꢊꢛꢉꢆꢇ (ꢉꢗꢅꢘ ꢆ% ꢘꢈꢊ ꢘ(ꢙ(ꢉ- %ꢞꢅꢛ'ꢊ +ꢞꢛ ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ%
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
6<
XR88C681
ꢆꢉ$ ꢍꢊ'ꢊ(ꢑꢊꢛ%ꢒ Table 17 ꢆꢉ$ Table 18 ꢗꢛꢊ%ꢊꢉꢘ ꢘꢈꢊ ꢛꢊꢇꢆꢘ(ꢞꢉ%ꢈ(ꢗ ꢚꢊꢘꢝꢊꢊꢉ ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ ꢀꢃꢍ% ꢆꢉ$ ꢘꢈꢊ 'ꢇꢞ'3 %ꢞꢅꢛ'ꢊ
$ꢛ(ꢑ(ꢉ- ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ% ꢆꢉ$ ꢍꢊ'ꢊ(ꢑꢊꢛ%ꢒ
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
ꢍꢊ'ꢊ(ꢑꢊꢛ ꢀꢇꢞ'3 ꢃꢊꢇꢊ'ꢘ
ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢀꢇꢞ'3 ꢃꢊꢇꢊ'ꢘ
ꢃꢊꢊ Table 18
ꢃꢊꢊ Table 18
Table 17. Bit Format of the Clock Select Registers, CSRA and CSRB
Field
Bit Rate
CSR[7:4]
CSR[3:0]
ACR[7] = 0
ACR[7] = 1
X = 0
6ꢕ
X = 1
>6
X = 0
>6
X = 1
ꢕ
ꢕ
ꢕ
ꢕ
ꢕ
ꢕ
ꢕ
ꢔ
ꢔ
ꢕ
ꢕ
ꢔ
ꢔ
ꢕ
ꢕ
ꢔ
ꢔ
ꢕ
ꢕ
ꢔ
ꢔ
ꢕ
ꢔ
ꢕ
ꢔ
ꢕ
ꢔ
ꢕ
ꢔ
ꢕ
ꢔ
ꢕ
ꢔ
ꢕ
ꢔ
ꢕ
ꢔ
6ꢕ
ꢔꢔꢕ
ꢕ
ꢕ
ꢕ
ꢔ
ꢔ
ꢔ
ꢔ
ꢕ
ꢕ
ꢕ
ꢕ
ꢔ
ꢔ
ꢔ
ꢔ
ꢔꢔꢕ
ꢔꢔꢕ
ꢔꢔꢕ
ꢔ1<ꢒ6
ꢓꢕꢕ
ꢔ1<ꢒ6
ꢔ1<ꢒ6
ꢔ6ꢕ
ꢔ1<ꢒ6
ꢔ6ꢕ
ꢓꢕꢕ
ꢕ
ꢕ
1ꢕꢕ
1/ꢕꢕ
1ꢕꢕ
1/ꢕꢕ
/ꢕꢕ
ꢔ<ꢒ<:
ꢓ=ꢒ=:
6>ꢒ/:
ꢔꢔ6ꢒꢓ:
<=ꢕꢕ
/ꢕꢕ
ꢔ<ꢒ<:
ꢕ
ꢕ
ꢔ
ꢔ
ꢔ
ꢔ
ꢔ
ꢔ
ꢔ
ꢔ
ꢔꢓꢕꢕ
ꢔꢕ6ꢕ
ꢓ<ꢕꢕ
<=ꢕꢕ
>ꢓꢕꢕ
ꢖ/ꢕꢕ
1=ꢒ<:
ꢎ(ꢙꢊꢛ
ꢔꢓꢕꢕ
ꢓ=ꢒ=:
ꢓꢕꢕꢕ
6>ꢒ/:
ꢓ<ꢕꢕ
ꢔꢔ6ꢒꢓ:
<=ꢕꢕ
<=ꢕꢕ
ꢔ=ꢕꢕ
ꢔ=ꢕꢕ
>ꢓꢕꢕ
ꢖ/ꢕꢕ
ꢖ/ꢕꢕ
ꢖ/ꢕꢕ
ꢔꢖꢒꢓ:
ꢎ(ꢙꢊꢛ
ꢔꢖꢒꢓ:
ꢎ(ꢙꢊꢛ
2!ꢘꢊꢛꢉꢆꢇ ꢜ ꢔ/5
2!ꢘꢊꢛꢉꢆꢇ ꢜ ꢔ5
1=ꢒ<:
ꢎ(ꢙꢊꢛ
2!ꢘꢊꢛꢉꢆꢇ ꢜ ꢔ/5
2!ꢘꢊꢛꢉꢆꢇ ꢜ ꢔ5
2!ꢘꢊꢛꢉꢆꢇ ꢜ ꢔ/5
2!ꢘꢊꢛꢉꢆꢇ ꢜ ꢔ5
2!ꢘꢊꢛꢉꢆꢇ ꢜ ꢔ/5
2!ꢘꢊꢛꢉꢆꢇ ꢜ ꢔ5
Note: the b suffix denotes a binary expression. x = don’t care value.
Table 18. Bit Format of the Clock Select Registers, CSR[3:0] and CSR[7:4]
Please note that ꢎꢆꢚꢇꢊ ꢔ= calls for the user to specify the
X - The Select Extend bit
following parameters4
ꢁ ꢌꢀꢍN>O ꢜ ꢘꢈꢊ ꢙꢞ%ꢘ %(-ꢉ(+('ꢆꢉꢘ ꢚ(ꢘ ꢏꢁꢃ*ꢐ ꢞ+ ꢘꢈꢊ ꢌꢅ!(ꢇꢜ
(ꢆꢛ& ꢀꢞꢉꢘꢛꢞꢇ ꢍꢊ-(%ꢘꢊꢛ
2ꢆ'ꢈ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢆꢉ$ ꢛꢊ'ꢊ(ꢑꢊꢛ" ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢈꢆ% ꢆꢉ
ꢊ!ꢘꢊꢉ$ ꢚ(ꢘ ꢘꢈꢆꢘ 'ꢆꢉ ꢚꢊ %ꢊꢘ ꢞꢛ 'ꢇꢊꢆꢛꢊ$ ꢚ& ꢝꢛ(ꢘ(ꢉ- ꢘꢈꢊ
ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ $ꢆꢘꢆ ꢘꢞ ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇH% ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛꢒ
ꢌꢇꢘꢈꢞꢅ-ꢈ ꢘꢈ(% (ꢉ+ꢞꢛꢙꢆꢘ(ꢞꢉ 'ꢆꢉ ꢚꢊ +ꢞꢅꢉ$ (ꢉ Table 3ꢒ
Table 19 %ꢅꢙꢙꢆꢛ(Iꢊ% ꢘꢈꢊ%ꢊ 'ꢞꢙꢙꢆꢉ$%" ꢆꢉ$ ꢘꢈꢊ(ꢛ ꢊ++ꢊ'ꢘ
ꢞꢉ ꢘꢈꢊ 2!ꢘꢊꢉ$ ꢚ(ꢘ%ꢒ
ꢁ 5 ꢜ ꢎꢈꢊ 2!ꢘꢊꢉ$ ꢚ(ꢘ
ꢌꢀꢍN>O (% ꢘꢈꢊ ꢁꢃ* ꢞ+ ꢘꢈꢊ ꢌꢅ!(ꢇ(ꢆꢛ& ꢀꢞꢉꢘꢛꢞꢇ ꢍꢊ-(%ꢘꢊꢛ" ꢆꢉ$
'ꢆꢉ ꢊꢆ%(ꢇ& ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢚ& ꢝꢛ(ꢘ(ꢉ- ꢔ!!!!!!!ꢚ ꢞꢛ
ꢕ!!!!!!!ꢚ ꢘꢞ ꢘꢈꢊ ꢌꢀꢍ" (ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ %ꢊꢘ ꢞꢛ 'ꢇꢊꢆꢛ"
ꢛꢊ%ꢗꢊ'ꢘ(ꢑꢊꢇ&ꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
66
XR88C681
Register
Contents
ꢕ=ꢔ/
Resulting Action
ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ ꢌ" ꢀꢍꢌ
ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ ꢌ" ꢀꢍꢌ
ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ *" ꢀꢍ*
ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ *" ꢀꢍ*
ꢃꢊꢘ ꢍ! *ꢍ0 ꢃꢊꢇꢊ'ꢘ 2!ꢘꢊꢉ$ *(ꢘ ꢏ5 J ꢔꢐ
ꢀꢇꢊꢆꢛ ꢍ! *ꢍ0 ꢃꢊꢇꢊ'ꢘ 2!ꢘꢊꢉ$ *(ꢘ ꢏ5 J ꢕꢐ
ꢃꢊꢘ ꢎ! *ꢍ0 ꢃꢊꢇꢊ'ꢘ 2!ꢘꢊꢉ$ *(ꢘ ꢏ5 J ꢔꢐ
ꢀꢇꢊꢆꢛ ꢎ! *ꢍ0 ꢃꢊꢇꢊ'ꢘ 2!ꢘꢊꢉ$ *(ꢘ ꢏ5 J ꢔꢐ
ꢕꢖꢔ/
ꢕꢌꢔ/
ꢕ*ꢔ/
Table 19. Command Register Controls Over the Extend Bit
Note: If the user programs either nibble of the Clock Select Register (CSRn[7:4] or CSRn[3:0]) with values ranging from 016 to C16,
then the user is using the BRG as a source for timing. However, these standard bit rates (presented in Table 18) apply only if
the X1/CLK pin is driven with a 3.6864 MHz signal. If a signal with a different frequency (fo) is applied to the X1/CLK pin, then
the DUART channel is running at the following baud rate:
Actual Baud Rate =
Nꢎꢆꢚꢇꢊ / *ꢆꢅ$ ꢍꢆꢘꢊ ;ꢆꢇꢅꢊO R +ꢞ
1ꢒ/=/< ꢁ8I
provided that fo is between 2.0 MHz and 4.0 MHz.
Additionally, as in the case for standard baud rates, the actual frequency of the clock signal will be 16 times these values.
1X vs 16X Clock Signals
ꢎꢈꢊ ꢘꢊꢛꢙ% Cꢔ5 ꢀꢇꢞ'3D ꢆꢉ$ Cꢔ/5 ꢀꢇꢞ'3D ꢈꢆꢑꢊ ꢚꢊꢊꢉ ꢆꢗꢗꢇ(ꢊ$
ꢘꢈꢛꢞꢅ-ꢈꢞꢅꢘ ꢘꢈ(% ꢘꢊ!ꢘꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" (ꢘ (% (ꢙꢗꢞꢛꢘꢆꢉꢘ ꢘꢞ $(%'ꢅ%%
ꢃꢅꢗꢗꢞ%ꢊ ꢘꢈꢆꢘ ꢝꢊ ꢈꢆꢑꢊ ꢆ %ꢊꢛ(ꢆꢇ $ꢆꢘꢆ ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉ %&%ꢘꢊꢙ
ꢆ% $ꢊꢗ('ꢘꢊ$ (ꢉ Figure 29ꢒ ꢎꢈ(% %&%ꢘꢊꢙ 'ꢞꢉ%(%ꢘ% ꢞ+ ꢆ
ꢛꢊꢙꢞꢘꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢏꢎ5ꢐ" ꢆꢉ$ ꢆ ꢇꢞ'ꢆꢇ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢏꢍ5ꢐꢒ
ꢘꢈꢊ(ꢛ ꢙꢊꢆꢉ(ꢉ- ꢆꢉ$ %(-ꢉ(+('ꢆꢉ'ꢊꢒ
ꢌ Cꢔ/5 'ꢇꢞ'3D
ꢞꢑꢊꢛꢜ%ꢆꢙꢗꢇꢊ% ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊ$ %ꢊꢛ(ꢆꢇ $ꢆꢘꢆ ꢚ& ꢆ +ꢆ'ꢘꢞꢛ ꢞ+ ꢔ/ꢒ
Bꢈꢊꢛꢊꢆ% ꢆ Cꢔ5 'ꢇꢞ'3D ꢞꢉꢇ& %ꢆꢙꢗꢇꢊ% ꢘꢈꢊ %(-ꢉꢆꢇ% ꢞꢉ'ꢊ ꢗꢊꢛ
ꢚ(ꢘ ꢗꢊꢛ(ꢞ$ꢒ ꢛꢞꢙ ꢘꢈ(% ꢞꢉꢊ %ꢈꢞꢅꢇ$ 'ꢞꢛꢛꢊ'ꢘꢇ& 'ꢞꢉ'ꢇꢅ$ꢊ ꢘꢈꢆꢘ
-ꢛꢊꢆꢘꢊꢛ ꢆ''ꢅꢛꢆ'& ꢏꢇꢞꢝꢊꢛ ꢚ(ꢘ ꢊꢛꢛꢞꢛ ꢛꢆꢘꢊ%ꢐ ꢆꢛꢊ ꢆ'ꢈ(ꢊꢑꢊ$ ꢑ(ꢆ
ꢘꢈꢊ ꢅ%ꢊ ꢞ+ ꢘꢈꢊ ꢔ/5 'ꢇꢞ'3 (ꢉ ꢇ(ꢊꢅ ꢞ+ ꢘꢈꢊ ꢔ5 'ꢇꢞ'3ꢒ ꢎꢈꢊ
+ꢞꢇꢇꢞꢝ(ꢉ- ꢗꢆꢛꢆ-ꢛꢆꢗꢈ% ꢝ(ꢇꢇ 'ꢇꢆꢛ(+& ꢘꢈꢊ ꢛꢊꢆ%ꢞꢉ%ꢒ
ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ
ꢎ5
ꢍꢊ'ꢊ(ꢑꢊꢛ
ꢍ5
ꢌ ꢛꢊ'ꢊ(ꢑꢊꢛ (ꢉ ꢞꢉꢊ ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ 'ꢈꢆꢉꢉꢊꢇ% (% 'ꢇꢞ'3ꢊ$ ꢚ& ꢆ
ꢇꢞ'ꢆꢇ ꢘ(ꢙ(ꢉ- %ꢞꢅꢛ'ꢊ ꢏ+ꢛꢞꢙ ꢘꢈꢊ ꢎ(ꢙ(ꢉ- ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3ꢐꢒ #+ ꢘꢈ(%
ꢛꢊ'ꢊ(ꢑꢊꢛ (% ꢆ'ꢘ(ꢑꢊ ꢆꢉ$ (% ꢛꢊ'ꢊ(ꢑ(ꢉ- $ꢆꢘꢆ +ꢛꢞꢙ ꢆ ꢛꢊꢙꢞꢘꢊ
%ꢊꢛ(ꢆꢇ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ" ꢘꢈꢆꢘ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% ꢆꢇ%ꢞ 'ꢇꢞ'3ꢊ$ ꢚ& (ꢘ%
ꢞꢝꢉ ꢇꢞ'ꢆꢇ ꢘ(ꢙ(ꢉ- %ꢞꢅꢛ'ꢊꢒ 8ꢊꢉ'ꢊ" ꢘꢈꢊꢛꢊ (% ꢉꢞ -ꢅꢆꢛꢆꢉꢘꢊꢊ
ꢘꢈꢆꢘ ꢘꢈꢊ 'ꢇꢞ'3 +ꢛꢊEꢅꢊꢉ'& +ꢞꢛ ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ (% ꢊ!ꢆ'ꢘꢇ& ꢘꢈꢊ
%ꢆꢙꢊ ꢆ% ꢘꢈꢆꢘ +ꢞꢛ ꢘꢈꢊ ꢛꢊꢙꢞꢘꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛꢒ ꢎꢈ(% (% ꢆ
ꢎ5 ꢀꢇꢞ'3
ꢍ5 ꢀꢇꢞ'3
Figure 29. Example of a Serial Data
Transmission System
'ꢈꢆꢛꢆ'ꢘꢊꢛ(%ꢘ('
ꢞ+
ꢆ%&ꢉ'ꢈꢛꢞꢉꢞꢅ%
%ꢊꢛ(ꢆꢇ
$ꢆꢘꢆ
'ꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉꢒ ꢌꢇꢘꢈꢞꢅ-ꢈ ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢆꢉ$ ꢛꢊꢙꢞꢘꢊ
ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢈꢆꢑꢊ ꢚꢊꢊꢉ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ ꢛꢊ'ꢊ(ꢑꢊ ꢆꢉ$
ꢘꢛꢆꢉ%ꢙ(ꢘ $ꢆꢘꢆ ꢆꢘ ꢊ!ꢆ'ꢘꢇ& ꢘꢈꢊ %ꢆꢙꢊ ꢚꢆꢅ$ ꢛꢆꢘꢊ" %ꢅ++('(ꢊꢉꢘ
$(++ꢊꢛꢊꢉ'ꢊ% (ꢉ ꢘꢈꢊ +ꢛꢊEꢅꢊꢉ'(ꢊ% ꢞ+ ꢘꢈꢊ ꢘꢝꢞ 'ꢇꢞ'3 %ꢞꢅꢛ'ꢊ%
ꢏꢇꢞ'ꢆꢇ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢆꢉ$ ꢛꢊꢙꢞꢘꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛꢐ 'ꢆꢉ 'ꢞꢉꢘꢛ(ꢚꢅꢘꢊ ꢘꢞ
ꢚ(ꢘ ꢊꢛꢛꢞꢛ% (ꢉ ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑ(ꢉ- ꢗꢛꢞ'ꢊ%%" ꢆ% ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ ꢘꢈꢊ
+ꢞꢇꢇꢞꢝ(ꢉ- $(%'ꢅ%%(ꢞꢉꢒ
9ꢊꢘ ꢅ% +ꢅꢛꢘꢈꢊꢛ ꢆ%%ꢅꢙꢊ ꢘꢈꢆꢘ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ (% 'ꢇꢞ'3ꢊ$ ꢚ& ꢆ
%ꢞꢅꢛ'ꢊ ꢘꢈꢆꢘ (% %ꢇ(-ꢈꢘꢇ& +ꢆ%ꢘꢊꢛ ꢘꢈꢆꢉ ꢘꢈꢆꢘ ꢞ+ ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ"
ꢆꢉ$ ꢘꢈꢆꢘ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ (% ꢞꢉꢇ& %ꢆꢙꢗꢇ(ꢉ- ꢘꢈꢊ %ꢊꢛ(ꢆꢇ $ꢆꢘꢆ ꢞꢉ'ꢊ
ꢗꢊꢛ ꢚ(ꢘ ꢗꢊꢛ(ꢞ$ꢒ Figure 30 ꢗꢛꢊ%ꢊꢉꢘ% ꢘꢈꢊ ꢛꢊ%ꢅꢇꢘ% ꢞ+ ꢘꢈ(%
ꢗꢈꢊꢉꢞꢙꢊꢉꢞꢉꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
6/
XR88C681
Figure 30. Receiver (1X) Sampling, if the RX Clock is Slightly Faster Than the TX Clock
Figure 30 %ꢈꢞꢝ% ꢘꢈꢆꢘ ꢘꢈꢊ ꢗꢈꢆ%ꢊ ꢛꢊꢇꢆꢘ(ꢞꢉ%ꢈ(ꢗ ꢚꢊꢘꢝꢊꢊꢉ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛH% %ꢆꢙꢗꢇ(ꢉ- ꢗꢞ(ꢉꢘ ꢆꢉ$ ꢊꢆ'ꢈ %ꢊꢛ(ꢆꢇ $ꢆꢘꢆ ꢚ(ꢘ (% 'ꢈꢆꢉ-(ꢉ-ꢒ
#ꢉ ꢘꢈ(% 'ꢆ%ꢊ" ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ (% %ꢆꢙꢗꢇ(ꢉ- ꢊꢆ'ꢈ %ꢊꢛ(ꢆꢇ $ꢆꢘꢆ ꢚ(ꢘ" ꢊꢆꢛꢇ(ꢊꢛ ꢆꢉ$ ꢊꢆꢛꢇ(ꢊꢛ (ꢉ ꢘꢈꢊ ꢚ(ꢘ ꢗꢊꢛ(ꢞ$" ꢝ(ꢘꢈ ꢊꢆ'ꢈ %ꢅ''ꢊ%%(ꢑꢊ $ꢆꢘꢆ
ꢚ(ꢘꢒ ꢎꢈ(% ꢗꢈꢊꢉꢞꢙꢊꢉꢞꢉ (% 3ꢉꢞꢝꢉ ꢆ% ꢛꢊ'ꢊ(ꢑꢊꢛ $ꢛ(+ꢘꢒ #+ ꢘꢈꢊꢛꢊ (% ꢉꢞ 'ꢞꢛꢛꢊ'ꢘ(ꢞꢉ +ꢞꢛ ꢛꢊ'ꢊ(ꢑꢊꢛ $ꢛ(+ꢘ" ꢘꢈꢊꢛꢊ ꢝ(ꢇꢇ ꢚꢊ ꢙꢆꢉ& ꢊꢛꢛꢞꢛ% (ꢉ ꢘꢈꢊ
ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉ ꢆꢉ$ ꢛꢊ'ꢊꢗꢘ(ꢞꢉ ꢞ+ ꢘꢈ(% %ꢊꢛ(ꢆꢇ $ꢆꢘꢆ" ꢆ% $ꢊꢗ('ꢘꢊ$ (ꢉ Figure 31ꢒ
ꢍꢊ'ꢊ(ꢑꢊ$ ꢄꢆꢘꢆ
ꢕ
ꢔ
ꢕ
ꢔ
ꢕ
ꢕ
ꢔ
ꢕ
ꢔ
ꢌ'ꢘꢅꢆꢇ ꢄꢆꢘꢆ
ꢕ
ꢔ
ꢕ
ꢔ
ꢕ
ꢔ
ꢕ
ꢔ
Figure 31. Illustration of an Error due to Receiver Drift
Figure 31 %ꢈꢞꢝ% ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ %ꢆꢙꢗꢇ(ꢉ- ꢆꢉ ꢊ(-ꢈꢘ ꢚ(ꢘ %ꢘꢛ(ꢉ- ꢞ+ $ꢆꢘꢆ ꢝ(ꢘꢈ ꢚ(ꢘ ꢗꢆꢘꢘꢊꢛꢉ ꢕꢔꢕꢔꢕꢔꢕꢒ It is interesting to note that, in
Figure 31, the Receiver sampled 01010010ꢒ #ꢘ %ꢈꢞꢅꢇ$ ꢚꢊ ꢉꢞꢘꢊ$ ꢘꢈꢆꢘ ꢍꢊ'ꢊ(ꢑꢊꢛ $ꢛ(+ꢘ 'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ ꢆ ꢗꢛꢞꢚꢇꢊꢙ (% ꢘꢈꢊ ꢇꢞ'ꢆꢇ
ꢍꢊ'ꢊ(ꢑꢊꢛ (% %ꢇꢞꢝꢊꢛ ꢘꢈꢆꢉ ꢘꢈꢊ ꢛꢊꢙꢞꢘꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ 'ꢇꢞ'3ꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
6>
XR88C681
#ꢉ -ꢊꢉꢊꢛꢆꢇ ꢘꢈꢊ ꢚ(ꢘꢜꢊꢛꢛꢞꢛꢜꢛꢆꢘꢊ" +ꢞꢛ ꢘꢈ(% Cꢅꢉ'ꢞꢛꢛꢊ'ꢘꢊ$D %&%ꢘꢊꢙ
(% ꢆ +ꢅꢉ'ꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢘ(ꢙ(ꢉ- $(++ꢊꢛꢊꢉ'ꢊ% ꢚꢊꢘꢝꢊꢊꢉ ꢘꢈꢊ ꢎ5 ꢆꢉ$
ꢍ5 ꢇꢞ'ꢆꢇ 'ꢇꢞ'3 %(-ꢉꢆꢇ%ꢒ 8ꢞꢝꢊꢑꢊꢛ" (ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ 'ꢞꢛꢛꢊ'ꢘ +ꢞꢛ
ꢍꢊ'ꢊ(ꢑꢊꢛ ꢄꢛ(+ꢘ ꢆꢉ$ ꢘꢞ ꢙ(ꢉ(ꢙ(Iꢊ ꢘꢈꢊ *2ꢍ $ꢅꢛ(ꢉ- %ꢊꢛ(ꢆꢇ $ꢆꢘꢆ
ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉ" ꢙꢆꢉ& ꢋꢌꢍꢎ% (ꢉ ꢘꢈꢊ ꢙꢆꢛ3ꢊꢘ ꢗꢇꢆ'ꢊ" ꢊꢙꢗꢇꢞ&
ꢍꢊ'ꢊ(ꢑꢊꢛ ꢂꢑꢊꢛ%ꢆꢙꢗꢇ(ꢉ- ꢞ+ ꢘꢈꢊ ꢃꢎꢌꢍꢎ ꢚ(ꢘꢒ Bꢈꢊꢉ ꢘꢈ(%
+ꢊꢆꢘꢅꢛꢊ (% ꢊꢙꢗꢇꢞ&ꢊ$" ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ" ꢅꢗꢞꢉ $ꢊꢘꢊ'ꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ
ꢃꢎꢌꢍꢎ ꢚ(ꢘ" ꢝ(ꢇꢇ ꢚꢊ-(ꢉ ꢞꢑꢊꢛ%ꢆꢙꢗꢇ(ꢉ- ꢘꢈ(% ꢃꢎꢌꢍꢎ ꢚ(ꢘ ꢚ&
%ꢞꢙꢊ (ꢉꢘꢊ-ꢊꢛ +ꢆ'ꢘꢞꢛꢒ ꢎ&ꢗ('ꢆꢇꢇ&" +ꢞꢛ ꢙꢞ%ꢘ ꢗꢛꢊ%ꢊꢉꢘ $ꢆ&
ꢋꢌꢍꢎ%" ꢘꢈ(% ꢞꢑꢊꢛꢜ%ꢆꢙꢗꢇꢊ +ꢆ'ꢘꢞꢛ (% ꢔ/ꢒ ꢏꢎꢈꢊ 5ꢍ==ꢀ/=ꢔ
$ꢊꢑ('ꢊ ꢆꢇ%ꢞ ꢆ''ꢞꢙꢙꢞ$ꢆꢘꢊ% ꢔ/5 ꢛꢊ'ꢊ(ꢑꢊꢛ ꢞꢑꢊꢛ%ꢆꢙꢗꢇ(ꢉ- ꢞ+
ꢘꢈꢊ ꢃꢎꢌꢍꢎ ꢚ(ꢘꢐꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" (ꢉ ꢘꢈꢊ%ꢊ $ꢊꢑ('ꢊ%" ꢝꢈꢊꢉ ꢘꢈꢊ
ꢍꢊ'ꢊ(ꢑꢊꢛ $ꢊꢘꢊ'ꢘ% ꢘꢈꢊ ꢞ''ꢅꢛꢛꢊꢉ'ꢊ ꢞ+ ꢆ ꢃꢎꢌꢍꢎ ꢚ(ꢘ" (ꢘ ꢏꢘꢈꢊ
ꢍꢊ'ꢊ(ꢑꢊꢛꢐ ꢝ(ꢇꢇ ꢚꢊ-(ꢉ ꢞꢑꢊꢛ%ꢆꢙꢗꢇ(ꢉ- ꢘꢈ(% ꢃꢎꢌꢍꢎ ꢚ(ꢘ ꢚ& ꢆ
+ꢆ'ꢘꢞꢛ ꢞ+ ꢔ/ꢒ 8ꢞꢝꢊꢑꢊꢛ" ꢆ+ꢘꢊꢛ > ꢔ/5 'ꢇꢞ'3 ꢗꢊꢛ(ꢞ$% ꢈꢆ%
ꢊꢇꢆꢗ%ꢊ$" ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢝ(ꢇꢇ ꢆ%%ꢅꢙꢊ ꢘꢈ(% ꢗꢞ(ꢉꢘ ꢏꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ
ꢃꢎꢌꢍꢎ ꢚ(ꢘꢐ ꢘꢞ ꢚꢊ ꢘꢈꢊ ꢙ($ ꢗꢞ(ꢉꢘ ꢞ+ ꢘꢈꢊ ꢚ(ꢘ ꢗꢊꢛ(ꢞ$" ꢆꢉ$ ꢝ(ꢇꢇ
'ꢊꢆ%ꢊ ꢞꢑꢊꢛ%ꢆꢙꢗꢇ(ꢉ- ꢞ+ ꢘꢈꢊ ꢃꢎꢌꢍꢎ ꢚ(ꢘ ꢆꢉ$ ꢞ+ ꢘꢈꢊ
%ꢅꢚ%ꢊEꢅꢊꢉꢘ $ꢆꢘꢆꢒ ꢛꢞꢙ ꢘꢈ(% ꢗꢞ(ꢉꢘ" ꢘꢈꢛꢞꢅ-ꢈ ꢘꢈꢊ ꢊꢉ$ ꢞ+ ꢘꢈꢊ
'ꢈꢆꢛꢆ'ꢘꢊꢛ" ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢝ(ꢇꢇ %ꢆꢙꢗꢇꢊ ꢘꢈꢊ %ꢊꢛ(ꢆꢇ $ꢆꢘꢆ %ꢘꢛꢊꢆꢙ
ꢆꢘ ꢘꢈꢊ ꢔ5 ꢛꢆꢘꢊꢒ ꢃꢘꢆꢘꢊ$ ꢆꢉꢞꢘꢈꢊꢛ ꢝꢆ&" ꢞꢉ'ꢊ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢈꢆ%
ꢛꢊꢆ'ꢈꢊ$" ꢝꢈꢆꢘ (ꢘ ꢚꢊꢇ(ꢊꢑꢊ% ꢘꢞ ꢚꢊ ꢘꢈꢊ ꢙ($ꢜꢗꢞ(ꢉꢘ ꢞ+ ꢘꢈꢊ ꢃꢎꢌꢍꢎ
ꢚ(ꢘ" ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢝ(ꢇꢇ" +ꢛꢞꢙ ꢘꢈꢆꢘ ꢗꢞ(ꢉꢘ" ꢚꢊ-(ꢉ %ꢆꢙꢗꢇ(ꢉ- ꢘꢈꢊ
%ꢊꢛ(ꢆꢇ $ꢆꢘꢆ ꢆꢘ ꢔꢜꢚ(ꢘ ꢗꢊꢛ(ꢞ$ (ꢉꢘꢊꢛꢑꢆꢇ ꢏ%ꢊꢊ Figure 32ꢐꢒ ꢌ+ꢘꢊꢛ
ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢈꢆ% ꢛꢊ'ꢊ(ꢑꢊ$ ꢘꢈꢊ ꢃꢎꢂ, ꢚ(ꢘ" (ꢘ ꢝ(ꢇꢇ ꢆꢝꢆ(ꢘ ꢘꢈꢊ
ꢞ''ꢅꢛꢛꢊꢉ'ꢊ ꢞ+ ꢘꢈꢊ ꢃꢎꢌꢍꢎ ꢚ(ꢘꢒ ꢂꢉ'ꢊ ꢘꢈꢊ ꢃꢎꢌꢍꢎ ꢚ(ꢘ ꢈꢆ%
ꢚꢊꢊꢉ $ꢊꢘꢊ'ꢘꢊ$" ꢘꢈ(% ꢞꢑꢊꢛ%ꢆꢙꢗꢇ(ꢉ- ꢗꢛꢞ'ꢊ$ꢅꢛꢊ (% ꢛꢊꢗꢊꢆꢘꢊ$ꢒ
ꢀꢈꢞ%ꢊꢉ ꢆ%
ꢘꢈꢊ ꢁ($ꢗꢞ(ꢉꢘ
ꢞ+ ꢘꢈꢊ *(ꢘ
ꢔ *(ꢘ ,ꢊꢛ(ꢞ$
>ꢜ ꢔ/5 'ꢇꢞ'3
ꢗꢊꢛ(ꢞ$%
Figure 32. The Typical Sampling Pattern of Each Receiver Within the XR88C681 Device.
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
6=
XR88C681
ꢎꢈꢊ ꢞꢑꢊꢛ%ꢆꢙꢗꢇ(ꢉ- ꢘꢊ'ꢈꢉ(Eꢅꢊ ꢙ(ꢘ(-ꢆꢘꢊ% ꢙꢆꢉ& ꢞ+ ꢘꢈꢊ %ꢊꢛ(ꢆꢇ
$ꢆꢘꢆ ꢚ(ꢘ ꢊꢛꢛꢞꢛ% ꢚ& ꢆꢘꢘꢊꢙꢗꢘ(ꢉ- ꢘꢞ ꢆ$Mꢅ%ꢘ ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ
%ꢆꢙꢗꢇ(ꢉ- ꢗꢞ(ꢉꢘ" ꢘꢞ ꢉꢊꢆꢛ ꢘꢈꢊ ꢙ($ꢗꢞ(ꢉꢘ ꢞ+ ꢘꢈꢊ ꢚ(ꢘ ꢗꢊꢛ(ꢞ$%" ꢞꢉ ꢆ
'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢘꢞ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢚꢆ%(%ꢒ ꢎꢈ(% ꢆꢗꢗꢛꢞꢆ'ꢈ (% %ꢅ''ꢊ%%+ꢅꢇ
+ꢞꢛ ꢘꢝꢞ ꢛꢊꢆ%ꢞꢉ%4
<ꢒ Bꢛ(ꢘꢊ ꢔ!!!!!!!ꢚ ꢘꢞ ꢌꢀꢍ ꢎꢈ(% %ꢘꢊꢗ %ꢊꢇꢊ'ꢘ% C*(ꢘ ꢍꢆꢘꢊD
ꢃꢊꢘ Sꢓ ꢗꢊꢛ Table 18 ꢞ+ ꢘꢈ(% $ꢆꢘꢆ %ꢈꢊꢊꢘꢒ
Bꢈꢊꢛꢊ ꢘꢈꢊ ꢚ %ꢅ++(! $ꢊꢉꢞꢘꢊ% ꢆ ꢚ(ꢉꢆꢛ& ꢊ!ꢗꢛꢊ%%(ꢞꢉ" ꢆꢉ$ !
$ꢊꢉꢞꢘꢊ% ꢆ C$ꢞꢉHꢘ 'ꢆꢛꢊD ꢑꢆꢇꢅꢊ +ꢞꢛ ꢘꢈꢊ ꢚ(ꢉꢆꢛ& ꢊ!ꢗꢛꢊ%%(ꢞꢉꢒ
6ꢒ Bꢛ(ꢘꢊ == ꢘꢞ ꢀꢃꢍꢌꢒ ꢎꢈ(% %ꢘꢊꢗ %ꢊꢘ% ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊ ꢆꢉ$
ꢔ/
ꢎꢛꢆꢉ%ꢙ(ꢘ ꢚ(ꢘ ꢛꢆꢘꢊ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢘꢞ ꢔꢔ6ꢒꢓ3ꢚꢗ% ꢏꢗꢊꢛ
ꢔꢒ #ꢘ ꢞ++ꢊꢛ% ꢗꢊꢛ(ꢞ$(' 'ꢞꢛꢛꢊ'ꢘ(ꢞꢉ ꢘꢞ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ %ꢆꢙꢗꢇ(ꢉ-
ꢗꢞ(ꢉꢘꢒ
Table 17 ꢆꢉ$ Table 18ꢐꢒ
ꢓꢒ #ꢘ ꢇ(ꢙ(ꢘ% ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ $ꢛ(+ꢘ ꢗꢈꢊꢉꢞꢙꢊꢉꢞꢉ ꢏꢚꢊꢘꢝꢊꢊꢉ
%ꢆꢙꢗꢇ(ꢉ- ꢗꢞ(ꢉꢘ ꢆ$Mꢅ%ꢘꢙꢊꢉꢘ%ꢐ ꢘꢞ ꢘ&ꢗ('ꢆꢇꢇ& ꢆꢘ ꢙꢞ%ꢘ ꢔꢓ ꢚ(ꢘ%
ꢏ= ꢚ(ꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛ A ꢗꢆꢛ(ꢘ& ꢆꢉ$ ꢃꢎꢂ, ꢚ(ꢘ%ꢐꢒ
Example B: Programming the Bit Rate via the
Counter/Timer
ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" (+ ꢘꢈꢊ ꢅ%ꢊꢛ %ꢊꢇꢊ'ꢘ% ꢘꢞ ꢛꢊ'ꢊ(ꢑꢊ $ꢆꢘꢆ ꢆꢘ ꢆ ꢚꢆꢅ$ ꢛꢆꢘꢊ
ꢞ+ ꢖ/ꢕꢕ ꢚꢆꢅ$L ꢅꢗꢞꢉ $ꢊꢘꢊ'ꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢃꢎꢌꢍꢎ ꢚ(ꢘ" ꢘꢈꢊ
ꢍꢊ'ꢊ(ꢑꢊꢛ ꢝ(ꢇꢇ ꢚꢊ-(ꢉ %ꢆꢙꢗꢇ(ꢉ- ꢘꢈꢊ $ꢆꢘꢆ ꢆꢘ ꢏꢖ/ꢕꢕ ! ꢔ/ꢐ J
ꢃꢅꢗꢗꢞ%ꢊ ꢘꢈꢊ ꢅ%ꢊꢛ ꢝ(%ꢈꢊ% ꢘꢞ ꢘꢛꢆꢉ%ꢙ(ꢘ ꢆꢉ$ ꢛꢊ'ꢊ(ꢑꢊ $ꢆꢘꢆ ꢆꢘ
/ꢓꢒ63ꢚꢗ% ꢑ(ꢆ ꢀꢈꢆꢉꢉꢊꢇ *ꢒ Please note that this particular
bit rate is not offered by the BRGꢒ #ꢉ ꢘꢈ(% 'ꢆ%ꢊ ꢘꢈꢊ ꢅ%ꢊꢛ 'ꢆꢉ
$ꢞ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ-ꢒ
ꢔ61"/ꢕꢕ8Iꢒ
8ꢞꢝꢊꢑꢊꢛ" ꢞꢉ'ꢊ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢈꢆ%
ꢞꢑꢊꢛ%ꢆꢙꢗꢇꢊ$ ꢅꢗ ꢘꢞ ꢘꢈꢊ >ꢘꢈ ꢔ61ꢒ/38I 'ꢇꢞ'3 ꢗꢅꢇ%ꢊ" (ꢘ ꢝ(ꢇꢇ
ꢙꢆꢛ3 ꢘꢈ(% ꢇꢞ'ꢆꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢙ($ꢗꢞ(ꢉꢘ ꢞ+ ꢘꢈꢊ ꢃꢎꢌꢍꢎ ꢚ(ꢘꢒ ꢛꢞꢙ
ꢘꢈ(% ꢗꢞ(ꢉꢘ ꢞꢉ" ꢘꢈꢊ ꢔ61ꢒ/38I 'ꢇꢞ'3 %(-ꢉꢆꢇ (% $(ꢑ($ꢊ$ ꢚ& ꢔ/ ꢘꢞ
-ꢊꢉꢊꢛꢆꢘꢊ ꢘꢈꢊ %ꢆꢙꢗꢇꢊ 'ꢇꢞ'3 ꢏꢖ/ꢕꢕ8Iꢐ +ꢞꢛ ꢘꢈꢊ ꢛꢊꢙꢆ(ꢉ(ꢉ-
$ꢆꢘꢆ ꢆꢉ$ ꢞꢑꢊꢛꢈꢊꢆ$ ꢚ(ꢘ% ꢞ+ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ
ꢔꢒ ꢄꢛ(ꢑꢊ ꢆ < ꢁ8I ꢎꢎ9 %(-ꢉꢆꢇ (ꢉꢘꢞ ꢘꢈꢊ 5ꢔ.ꢀ9: ꢗ(ꢉ" ꢝꢈ(ꢇꢊ
ꢘꢈꢊ 5ꢓ ꢗ(ꢉ (% ꢇꢊ+ꢘ +ꢇꢞꢆꢘ(ꢉ-ꢒ
ꢓꢒ Bꢛ(ꢘꢊ ꢕꢕ ꢘꢞ ꢀꢎꢋꢍ ꢆꢉ$ ꢕꢓ ꢘꢞ ꢀꢎ9ꢍꢒ ꢎꢈ(% %ꢘꢊꢗ%
ꢔ/
ꢔ/
ꢛꢊ%ꢅꢇꢘ% (ꢉ ꢘꢈꢊ ꢀ.ꢎ -ꢊꢉꢊꢛꢆꢘ(ꢉ- ꢆ %Eꢅꢆꢛꢊ ꢝꢆꢑꢊ ꢞ+
ꢒ
+ꢛꢊEꢅꢊꢉ'& J < ꢁ8I.ꢓ NꢓO J ꢔ ꢁ8Iꢒ
ꢎꢈꢊ 5ꢍ==ꢀ/=ꢔ $ꢊꢑ('ꢊ% -(ꢑꢊ% ꢘꢈꢊ ꢅ%ꢊꢛ ꢘꢈꢊ ꢞꢗꢘ(ꢞꢉ ꢘꢞ
$ꢊ'ꢇꢆꢛꢊ ꢆꢉ ꢊ!ꢘꢊꢛꢉꢆꢇ (ꢉꢗꢅꢘ 'ꢇꢞ'3 %(-ꢉꢆꢇ ꢆ% ꢊ(ꢘꢈꢊꢛ ꢆ ꢔ5 ꢞꢛ
ꢔ/5 'ꢇꢞ'3 %(-ꢉꢆꢇꢒ Bꢈꢊꢉꢊꢑꢊꢛ ꢘꢈꢊ ꢅ%ꢊꢛ (% -(ꢑꢊꢉ ꢆ 'ꢈꢞ('ꢊ ꢘꢞ
ꢅ%ꢊ ꢊ(ꢘꢈꢊꢛ ꢘꢈꢊ ꢔ5 ꢞꢛ ꢔ/5 'ꢇꢞ'3 %(-ꢉꢆꢇ ꢏꢗꢊꢛ ꢘꢈꢊ ꢀꢇꢞ'3 ꢃꢊꢇꢊ'ꢘ
ꢍꢊ-(%ꢘꢊꢛ%ꢐ" ꢘꢈꢊ ꢅ%ꢊꢛ (% ꢆ$ꢑ(%ꢊ$ ꢘꢞ ꢆꢇꢝꢆ&% ꢅ%ꢊ ꢘꢈꢊ ꢔ/5
'ꢇꢞ'3" (ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ ꢙ(ꢘ(-ꢆꢘꢊ ꢘꢈꢊ ꢊ++ꢊ'ꢘ% ꢞ+ ꢛꢊ'ꢊ(ꢑꢊꢛ $ꢛ(+ꢘꢒ ꢎꢈꢊ
ꢅ%ꢊꢛ (% +ꢅꢛꢘꢈꢊꢛ ꢆ$ꢑ(%ꢊ$ ꢉꢊꢑꢊꢛ ꢘꢞ ꢅ%ꢊ ꢘꢈꢊ ꢔ5 'ꢇꢞ'3 +ꢊꢆꢘꢅꢛꢊ%
ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ" ꢅꢉꢇꢊ%% ꢘꢈꢊ (ꢉ'ꢞꢙ(ꢉ- %ꢊꢛ(ꢆꢇ $ꢆꢘꢆ %ꢘꢛꢊꢆꢙ (%
%&ꢉ'ꢈꢛꢞꢉꢞꢅ% ꢝ(ꢘꢈ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢏꢔ5ꢐ 'ꢇꢞ'3ꢒ
1ꢒ Bꢛ(ꢘꢊ ꢔꢔꢕꢚ ꢘꢞ ꢌꢀꢍN/4<O ꢎꢈ(% ꢝ(ꢇꢇ %ꢊꢘ ꢘꢈꢊ ꢀ.ꢎ (ꢉꢘꢞ ꢘꢈꢊ
ꢎ(ꢙꢊꢛ ꢙꢞ$ꢊ" ꢆꢉ$ %ꢊꢇꢊ'ꢘ ꢘꢈꢊ ꢎ(ꢙ(ꢉ- %ꢞꢅꢛ'ꢊ +ꢞꢛ ꢘꢈꢊ ꢀ.ꢎ
ꢘꢞ ꢚꢊ ꢘꢈꢊ 5ꢔ.ꢀ9: (ꢉꢗꢅꢘꢒ
<ꢒ Bꢛ(ꢘꢊ ꢄꢄ ꢘꢞ ꢀꢃꢍ*ꢒ ꢎꢈ(% ꢝ(ꢇꢇ %ꢗꢊ'(+& ꢘꢈꢆꢘ ꢘꢈꢊ ꢘ(ꢙ(ꢉ-
ꢔ/
%ꢞꢅꢛ'ꢊ +ꢞꢛ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢆꢉ$ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢞ+ ꢀꢈꢆꢉꢉꢊꢇ *
ꢝ(ꢇꢇ ꢚꢊ $ꢊꢛ(ꢑꢊ$ +ꢛꢞꢙ ꢘꢈꢊ ꢀ.ꢎꢒ Please note that when the
DUART is programmed in this configuration, the C/T
output represents a 16X over sample of the
Transmitted and Received dataꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢘꢈꢊ 'ꢈ(ꢗ
'(ꢛ'ꢅ(ꢘꢛ& ꢝ(ꢇꢇ $(ꢑ($ꢊ ꢘꢈꢊ ꢔ ꢁ8I %Eꢅꢆꢛꢊ ꢝꢆꢑꢊ ꢚ& ꢔ/" Mꢅ%ꢘ
ꢇ(3ꢊ +ꢞꢛ 'ꢇꢞ'3 %(-ꢉꢆꢇ% ꢞꢛ(-(ꢉꢆꢘ(ꢉ- +ꢛꢞꢙ ꢘꢈꢊ *ꢍ0ꢒ
D.6 Application Examples using the Timing Control
Block
ꢎꢈꢅ%4 *(ꢘ ꢍꢆꢘꢊ J ꢔ ꢁ8I.ꢔ/ J /ꢓꢒ63ꢚꢗ%ꢒ
#ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ 'ꢇꢆꢛ(+& ꢘꢈꢊ ꢛꢞꢇꢊ% ꢞ+ ꢘꢈꢊ ꢆ%%ꢊꢘ% ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢎ(ꢙ(ꢉ-
ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3" ꢘꢈꢛꢊꢊ ꢊ!ꢆꢙꢗꢇꢊ% ꢆꢛꢊ (ꢉ'ꢇꢅ$ꢊ$ꢒ
Example C: Using the External Input Ports
Example A: Using the BRG
ꢃꢅꢗꢗꢞ%ꢊ ꢘꢈꢆꢘ" (ꢉ ꢆ$$(ꢘ(ꢞꢉ ꢘꢞ ꢛꢅꢉꢉ(ꢉ- ꢀꢈꢆꢉꢉꢊꢇ * ꢆꢘ
/ꢓꢒ63ꢚꢗ% ꢏ%ꢊꢊ 2!ꢆꢙꢗꢇꢊ *ꢐ" ꢈꢊ.%ꢈꢊ ꢝꢆꢉꢘ% ꢘꢞ ꢎꢛꢆꢉ%ꢙ(ꢘ ꢆꢉ$
ꢍꢊ'ꢊ(ꢑꢊ $ꢆꢘꢆ ꢆꢘ ꢔ ꢁꢚꢗ% ꢑ(ꢆ ꢀꢈꢆꢉꢉꢊꢇ ꢌꢒ
ꢃꢅꢗꢗꢞ%ꢊ ꢘꢈꢆꢘ ꢘꢈꢊ ꢅ%ꢊꢛ ꢝ(%ꢈꢊ% ꢘꢞ ꢛꢊ'ꢊ(ꢑꢊ ꢆꢉ$ ꢘꢛꢆꢉ%ꢙ(ꢘ $ꢆꢘꢆ
ꢆꢘ ꢆ ꢛꢆꢘꢊ ꢞ+ ꢔꢔ6ꢒꢓ3ꢚꢗ% ꢑ(ꢆ ꢀꢈꢆꢉꢉꢊꢇ ꢌꢒ ꢎꢈꢊ ꢅ%ꢊꢛ ꢙꢅ%ꢘ $ꢞ
ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ-4
ꢎꢈꢊ ꢅ%ꢊꢛ ꢉꢊꢊ$% ꢘꢞ ꢗꢊꢛ+ꢞꢛꢙ ꢆꢇꢇ ꢞ+ ꢘꢈꢊ %ꢘꢊꢗ% ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ
2!ꢆꢙꢗꢇꢊ *" ꢆꢇꢞꢉ- ꢝ(ꢘꢈ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ-4
ꢔꢒ ꢋ%ꢊ ꢆ 1ꢒ/=/< ꢁ8I 'ꢛ&%ꢘꢆꢇ ꢞ%'(ꢇꢇꢆꢘꢞꢛ ꢆ'ꢛꢞ%% ꢘꢈꢊ
5ꢔ.ꢀ9: ꢆꢉ$ 5ꢓ ꢗ(ꢉ%L ꢞꢛ $ꢛ(ꢑ(ꢉ- ꢆ 1ꢒ/=/< ꢁ8I ꢎꢎ9
%(-ꢉꢆꢇ (ꢉꢘꢞ ꢘꢈꢊ 5ꢔ.ꢀ9: ꢗ(ꢉ ꢏꢝ(ꢘꢈ ꢘꢈꢊ 5ꢓ ꢗ(ꢉ +ꢇꢞꢆꢘ(ꢉ-ꢐꢒ
ꢔꢒ Bꢛ(ꢘꢊ !!!!ꢕꢔ!!ꢚ ꢘꢞ ꢘꢈꢊ ꢂ,ꢀꢍ ꢏꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ
ꢀꢞꢉ+(-ꢅꢛꢆꢘ(ꢞꢉ ꢍꢊ-(%ꢘꢊꢛꢐꢒ
ꢓꢒ Bꢛ(ꢘꢊ ꢕꢌ ꢘꢞ ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ ꢌꢒ ꢎꢈ(% %ꢘꢊꢗ ꢝ(ꢇꢇ %ꢊꢘ
ꢔ/
ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ *ꢍ0 ꢃꢊꢇꢊ'ꢘ 2!ꢘꢊꢉ$ ꢚ(ꢘ ꢏ5 J ꢔꢐꢒ
ꢎꢈ(% %ꢘꢊꢗ ꢆꢇꢇꢞꢝ% ꢘꢈꢊ ꢔ ꢁ8I %Eꢅꢆꢛꢊ ꢝꢆꢑꢊ +ꢛꢞꢙ ꢘꢈꢊ ꢀ.ꢎ ꢘꢞ
ꢚꢊ ꢞꢅꢘꢗꢅꢘ ꢞꢉ ꢂ,1ꢒ
1ꢒ Bꢛ(ꢘꢊ ꢕ= ꢘꢞ ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ ꢌꢒ ꢎꢈ(% %ꢘꢊꢗ ꢝ(ꢇꢇ %ꢊꢘ
ꢔ/
ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ *ꢍ0 ꢃꢊꢇꢊ'ꢘ 2!ꢘꢊꢉ$ ꢚ(ꢘ ꢏ5 J ꢔꢐꢒ
7ꢞꢘꢊ4 ! J $ꢞꢉHꢘ 'ꢆꢛꢊ
ꢎꢈꢊ ꢚ %ꢅ++(! $ꢊꢉꢞꢘꢊ% ꢆ ꢚ(ꢉꢆꢛ& ꢊ!ꢗꢛꢊ%%(ꢞꢉ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
6ꢖ
XR88C681
ꢓꢒ 2!ꢘꢊꢛꢉꢆꢇꢇ& 'ꢞꢉꢉꢊ'ꢘ ꢘꢈꢊ ꢂ,1 ꢗ(ꢉ ꢘꢞ ꢘꢈꢊ #,1 ꢆꢉ$ #,< ꢗ(ꢉ%ꢒ
ꢎꢈꢊꢛꢊꢚ& ꢆꢗꢗꢇ&(ꢉ- ꢆ ꢔ ꢁ8I %Eꢅꢆꢛꢊ ꢝꢆꢑꢊ (ꢉꢘꢞ ꢘꢈꢊ%ꢊ ꢘꢝꢞ
(ꢉꢗꢅꢘ ꢗ(ꢉ%ꢒ
incoming serial data stream is synchronous with the 1
MHz (1X) clock signal; in order to minimize bit errorsꢒ
1ꢒ Bꢛ(ꢘꢊ ꢘꢞ ꢀꢃꢍꢌꢒ
ꢔ/
D.7 Explanation of Clock Timing Signals
ꢎꢈ(% %ꢘꢊꢗ ꢝ(ꢇꢇ %ꢗꢊ'(+& ꢘꢈꢆꢘ ꢘꢈꢊ ꢘ(ꢙ(ꢉ- %ꢞꢅꢛ'ꢊ +ꢞꢛ ꢘꢈꢊ
ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢆꢉ$ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢞ+ ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢝ(ꢇꢇ ꢚꢊ $ꢊꢛ(ꢑꢊ$
+ꢛꢞꢙ (ꢉꢗꢅꢘ ꢗ(ꢉ% #,1 ꢆꢉ$ #,<" ꢛꢊ%ꢗꢊ'ꢘ(ꢑꢊꢇ&ꢒ ꢌ$$(ꢘ(ꢞꢉꢆꢇꢇ&"
ꢘꢈ(% %ꢘꢊꢗ ꢆꢇꢇꢞꢝ ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢈꢆꢛ$ꢝꢆꢛꢊ ꢘꢞ ꢗꢛꢊ%ꢅꢙꢊ ꢘꢈꢆꢘ
ꢘꢈꢊ%ꢊ (ꢉꢗꢅꢘ %(-ꢉꢆꢇ ꢆꢛꢊ ꢔ5 %(-ꢉꢆꢇ%ꢒ 8ꢊꢉ'ꢊ" ꢘꢈꢊꢛꢊ (% ꢉꢞ
$(ꢑ(%(ꢞꢉꢜꢚ&ꢜꢔ/ ꢞ+ ꢘꢈ(% %(-ꢉꢆꢇꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢘꢈꢊ ꢚ(ꢘ ꢛꢆꢘꢊ ꢞ+
ꢀꢈꢆꢉꢉꢊꢇ ꢌ (% ꢆꢘ ꢔ ꢁꢚꢗ%ꢒ
ꢎꢈꢊ ꢗꢅꢛꢗꢞ%ꢊ ꢞ+ ꢘꢈ(% %ꢊ'ꢘ(ꢞꢉ (% ꢘꢞ ꢊ!ꢗꢇꢆ(ꢉ ꢘꢈꢊ ꢄꢆꢘꢆ ꢃꢈꢊꢊꢘ
%ꢗꢊ'(+('ꢆꢘ(ꢞꢉ ꢞꢉ ꢘꢈꢊ ꢎ(ꢙ(ꢉ- ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3 ꢗꢆꢛꢆꢙꢊꢘꢊꢛ%ꢒ #ꢉ
ꢘꢈꢊ ꢗꢆ%ꢘ" ꢘꢈ(% %ꢅꢚMꢊ'ꢘ ꢈꢆ% ꢚꢊꢊꢉ ꢘꢈꢊ %ꢞꢅꢛ'ꢊ ꢞ+ 'ꢞꢉ%($ꢊꢛꢆꢚꢇꢊ
'ꢞꢉ+ꢅ%(ꢞꢉ ꢚ& ꢉꢅꢙꢊꢛꢞꢅ% ꢅ%ꢊꢛ%ꢒ
ꢎꢈꢊ 5ꢍ==ꢀ/=ꢔ ꢄꢆꢘꢆ ꢃꢈꢊꢊꢘ ꢗꢛꢊ%ꢊꢉꢘ% ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ-
ꢗꢆꢛꢆꢙꢊꢘꢊꢛ %ꢗꢊ'(+('ꢆꢘ(ꢞꢉ% (ꢉ ꢘꢈꢊ
Cꢌꢀ 292ꢀꢎꢍ#ꢀꢌ9 ꢀ8ꢌꢍꢌꢀꢎ2ꢍ#ꢃꢎ#ꢀꢃD
Please note that if the user were to apply this example,
he/she would be responsible for ensuring that the
Symbol
Parameter
Min.
ꢔꢕꢕ
ꢓꢒꢕ
Typ.
Max.
Units
ꢉ%
ꢘꢀ9:
5ꢔ.ꢀ9: ꢏ2!ꢘꢊꢛꢉꢆꢇꢐ 8(-ꢈ ꢞꢛ 9ꢞꢝ ꢎ(ꢙꢊ
5ꢔ.ꢀ9: ꢀꢛ&%ꢘꢆꢇ ꢞꢛ 2!ꢘꢊꢛꢉꢆꢇ ꢛꢊEꢅꢊꢉ'&
+
1ꢒ/=/<
<ꢒꢕ
ꢁ8I
ꢉ%
ꢀ9:
ꢘꢀꢎꢀ
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ 2!ꢘꢊꢛꢉꢆꢇ ꢀꢇꢞ'3 8(-ꢈ ꢞꢛ 9ꢞꢝ
ꢎ(ꢙꢊ ꢜ #,ꢓ #ꢉꢗꢅꢘ
ꢔꢕꢕ
+
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ 2!ꢘꢊꢛꢉꢆꢇ ꢀꢇꢞ'3 ꢛꢊEꢅꢊꢉ'& ꢜ #,ꢓ
#ꢉꢗꢅꢘ
ꢕ
<ꢒꢕ
ꢁ8I
ꢉ%
ꢀꢎꢀ
ꢘꢍꢎ5
ꢍ5ꢀ ꢆꢉ$ ꢎ5ꢀ ꢏ2!ꢘꢊꢛꢉꢆꢇꢐ 8(-ꢈ ꢞꢛ 9ꢞꢝ ꢎ(ꢙꢊ ꢜ
ꢑ(ꢆ #,ꢓ" #,1" #,< ꢆꢉ$ #,6
ꢓꢓꢕ
+
ꢍ5ꢀ ꢆꢉ$ ꢎ5ꢀ ꢏ2!ꢘꢊꢛꢉꢆꢇꢐ ꢛꢊEꢅꢊꢉ'& ꢜ ꢑ(ꢆ #,ꢓ"
#,1" #,<" ꢆꢉ$ #,6
ꢍꢎ5
+
+
ꢍꢎ5 ꢜ ꢔ/5
ꢍꢎ5 ꢜ ꢔ5
ꢔ/5
ꢔ5
ꢕ
ꢕ
ꢓꢒꢕ
ꢔꢒꢕ
ꢁ8I
ꢁ8I
Table 20. Clock Timing (Figure 13)
7ꢞꢝ" ꢈꢊꢛꢊ (% ꢆꢉ ꢊ!ꢗꢇꢆꢉꢆꢘ(ꢞꢉ +ꢞꢛ ꢊꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ ꢗꢆꢛꢆꢙꢊꢘꢊꢛ%ꢒ
ꢁ t
- X1/CLK (External) High or Low Time
ꢁ t
- Counter/Timer External Clock High or Low
CTC
CLK
Time - IP2 Input
ꢎꢈꢊ ꢄꢋꢌꢍꢎ ꢊꢙꢗꢇꢞ&% $&ꢉꢆꢙ(' ꢇꢞ-(' ꢘꢈꢛꢞꢅ-ꢈꢞꢅꢘ ꢙꢅ'ꢈ ꢞ+
(ꢘ% '(ꢛ'ꢅ(ꢘꢛ&ꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢇ(ꢙ(ꢘ% ꢞꢉ ꢘꢀ9: ꢆꢉ$ +ꢀ9: ꢆꢛꢊ
ꢉꢊꢊ$ꢊ$ (ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ ꢊꢉ%ꢅꢛꢊ ꢘꢈꢆꢘ ꢘꢈꢊ $ꢊꢑ('ꢊ ꢝ(ꢇꢇ +ꢅꢉ'ꢘ(ꢞꢉ
ꢗꢛꢞꢗꢊꢛꢇ&ꢒ ꢎꢈ(% ꢗꢆꢛꢆꢙꢊꢘꢊꢛ Mꢅ%ꢘ ꢗꢇꢆ'ꢊ% ꢆ ꢇꢞꢝꢊꢛ ꢇ(ꢙ(ꢘ ꢞꢉ ꢘꢈꢊ
ꢆꢙꢞꢅꢉꢘ ꢞ+ ꢘ(ꢙꢊ ꢆꢘ ꢘꢈꢊ %(-ꢉꢆꢇ ꢆꢗꢗꢇ(ꢊ$ ꢘꢈꢛꢞꢅ-ꢈ ꢘꢈꢊ 5ꢔ.ꢀ9:
ꢗ(ꢉ ꢙꢅ%ꢘ ꢛꢊ%($ꢊ ꢆꢘ ꢘꢈꢊ ꢈ(-ꢈ ꢆꢉ$ ꢇꢞꢝ %ꢘꢆꢘꢊ%ꢒ
ꢎꢈ(% ꢗꢆꢛꢆꢙꢊꢘꢊꢛ ꢗꢇꢆ'ꢊ% ꢆ ꢇꢞꢝꢊꢛ ꢇ(ꢙ(ꢘ ꢞꢉ ꢘꢈꢊ ꢆꢙꢞꢅꢉꢘ ꢞ+ ꢘ(ꢙꢊ
ꢘꢈꢆꢘ ꢘꢈꢊ %(-ꢉꢆꢇ" ꢚꢊ(ꢉ- ꢆꢗꢗꢇ(ꢊ$ ꢘꢞ ꢘꢈꢊ #,ꢓ ꢗ(ꢉ" +ꢞꢛ ꢅ%ꢊ ꢚ& ꢘꢈꢊ
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ" 'ꢆꢉ ꢛꢊ%($ꢊ ꢆꢘ ꢘꢈꢊ ꢈ(-ꢈ ꢆꢉ$ ꢇꢞꢝ %ꢘꢆꢘꢊ%ꢒ
Please note that this limit has no relationship with the
parameter tRTX, which is another spec associated with
the IP2 input.
ꢁ f
- X1/CLK Crystal High or Low Time
CLK
ꢁ f
- Counter/Timer External Clock Frequency -
CTC
ꢎꢈ(% ꢗꢆꢛꢆꢙꢊꢘꢊꢛ %ꢗꢊ'(+(ꢊ% ꢘꢈꢊ ꢛꢆꢉ-ꢊ ꢞ+ +ꢛꢊEꢅꢊꢉ'(ꢊ%
ꢗꢊꢛꢙ(%%(ꢚꢇꢊ ꢆꢘ ꢘꢈꢊ 5ꢔ.ꢀ9: (ꢉꢗꢅꢘ" ꢑ(ꢆ ꢊ(ꢘꢈꢊꢛ 'ꢛ&%ꢘꢆꢇ
ꢞ%'(ꢇꢇꢆꢘꢞꢛ ꢞꢛ ꢆꢗꢗꢇ(ꢊ$ ꢎꢎ9 (ꢉꢗꢅꢘ %(-ꢉꢆꢇꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢘꢈꢊ ꢅ%ꢊ
'ꢆꢉ ꢞꢉꢇ& ꢆꢗꢗꢇ& ꢚꢊꢘꢝꢊꢊꢉ ꢓꢒꢕ ꢆꢉ$ <ꢒꢕ ꢁ8I ꢆꢘ ꢘꢈ(% (ꢉꢗꢅꢘꢒ
IP2 Input
ꢎꢈ(% ꢗꢆꢛꢆꢙꢊꢘꢊꢛ ꢗꢇꢆ'ꢊ% ꢆꢉ ꢅꢗꢗꢊꢛ ꢇ(ꢙ(ꢘ ꢞ+ ꢘꢈꢊ (ꢉꢗꢅꢘ
+ꢛꢊEꢅꢊꢉ'& ꢚꢊ(ꢉ- ꢆꢗꢗꢇ(ꢊ$ ꢘꢞ ꢘꢈꢊ #,ꢓ ꢗ(ꢉ" +ꢞꢛ ꢅ%ꢊ ꢚ& ꢘꢈꢊ
ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛꢒ ꢎꢈꢊ %ꢗꢊ' ꢚꢆ%('ꢆꢇꢇ& %ꢘꢆꢘꢊ% ꢘꢈꢆꢘ ꢆ %(-ꢉꢆꢇ
ꢝ(ꢘꢈ +ꢛꢊEꢅꢊꢉ'& ꢅꢗ ꢘꢞ <ꢒꢕ ꢁ8I 'ꢆꢉ ꢚꢊ ꢆꢗꢗꢇ(ꢊ$ ꢆꢘ ꢘꢈꢊ #,ꢓ
ꢗ(ꢉ" ꢆꢉ$ %ꢘ(ꢇꢇ ꢚꢊ ꢗꢛꢞꢗꢊꢛꢇ& ꢈꢆꢉ$ꢇꢊ$ ꢚ& ꢘꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛꢒ
ꢎꢈ(% %ꢗꢊ' (% ꢉꢞꢘ ꢛꢊꢇꢆꢘꢊ$ ꢘꢞ ꢘꢈꢊ ꢗꢆꢛꢆꢙꢊꢘꢊꢛ ꢘꢍꢎ5" ꢝꢈ('ꢈ ꢆꢇ%ꢞ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
/ꢕ
XR88C681
%ꢗꢊ'(+(ꢊ% ꢇ(ꢙ(ꢘ% ꢞꢉ %(-ꢉꢆꢇ% ꢆꢗꢗꢇ(ꢊ$ ꢘꢞ #,ꢓ ꢞꢛ ꢞꢘꢈꢊꢛ (ꢉꢗꢅꢘ
ꢗ(ꢉ%" +ꢞꢛ ꢅ%ꢊ ꢆꢘ ꢘꢈꢊ 2!ꢘꢊꢛꢉꢆꢇ ꢀꢇꢞ'3 ꢃꢞꢅꢛ'ꢊ +ꢞꢛ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ
ꢆꢉ$ ꢍꢊ'ꢊ(ꢑꢊꢛ%ꢒ
ꢞꢛ %ꢈꢊ $ꢊ%(ꢛꢊ%ꢒ ꢎꢈꢊ ꢎ(ꢙ(ꢉ- ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3 -(ꢑꢊ% ꢘꢈꢊ ꢅ%ꢊꢛ
ꢆ''ꢊ%% ꢘꢞ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- ꢛꢊ%ꢞꢅꢛ'ꢊ%4
ꢁ ꢓ1 $(++ꢊꢛꢊꢉꢘ %ꢘꢆꢉ$ꢆꢛ$ ꢚ(ꢘ ꢛꢆꢘꢊ% ꢑ(ꢆ ꢘꢈꢊ *ꢍ0ꢒ
ꢁ ꢎꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ" ꢝꢈ('ꢈ 'ꢆꢉ ꢚꢊ 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ -ꢊꢉꢜ
ꢊꢛꢆꢘꢊ ꢚ(ꢘ ꢛꢆꢘꢊ% ꢝꢈ('ꢈ ꢆꢛꢊ ꢉꢞꢘ ꢆꢑꢆ(ꢇꢆꢚꢇꢊ +ꢛꢞꢙ ꢘꢈꢊ *ꢍ0ꢒ
ꢁ #ꢉꢗꢅꢘ% ꢘꢞ ꢘꢈꢊ ꢎ(ꢙ(ꢉ- ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3 ꢏꢑ(ꢆ %ꢞꢙꢊ #ꢉꢗꢅꢘ
,ꢞꢛꢘ ꢗ(ꢉ%ꢐ ꢝꢈ('ꢈ ꢆꢇꢇꢞꢝ% ꢘꢈꢊ ꢅ%ꢊ ꢞ+ ꢊ!ꢘꢊꢛꢉꢆꢇ 'ꢇꢞ'3 %(-ꢜ
ꢉꢆꢇ% ꢘꢞ -ꢊꢉꢊꢛꢆꢘꢊ ꢆ 'ꢅ%ꢘꢞꢙ ꢚ(ꢘ ꢛꢆꢘꢊꢒ
ꢁ t
- RXC and TXC (External) High or Low Time
RTX
- via IP2, IP3, IP4 and IP5
ꢎꢈ(% %ꢗꢊ' ꢗꢇꢆ'ꢊ% ꢆ ꢇꢞꢝꢊꢛ ꢇ(ꢙ(ꢘ ꢞꢉ ꢘꢈꢊ ꢆꢙꢞꢅꢉꢘ ꢞ+ ꢘ(ꢙꢊ ꢘꢈꢆꢘ ꢆ
%(-ꢉꢆꢇ" ꢚꢊ(ꢉ- ꢆꢗꢗꢇ(ꢊ$ ꢆꢘ ꢘꢈꢊ 0ꢊꢉꢊꢛꢆꢇ ,ꢅꢛꢗꢞ%ꢊ #ꢉꢗꢅꢘ ,(ꢉ%"
#,ꢓ ꢜ #,6" +ꢞꢛ ꢅ%ꢊ ꢆ% ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢆꢉ$ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢀꢇꢞ'3
%ꢞꢅꢛ'ꢊ" 'ꢆꢉ ꢛꢊ%($ꢊ ꢆꢘ ꢘꢈꢊ ꢈ(-ꢈ ꢞꢛ ꢇꢞꢝ %ꢘꢆꢘꢊꢒ ꢎꢈ(% %ꢗꢊ' ꢈꢆ%
E. INPUT PORT
ꢉꢞ ꢛꢊꢇꢆꢘ(ꢞꢉ%ꢈ(ꢗ ꢘꢞ ꢘ
#ꢉꢗꢅꢘ ꢗ(ꢉ #,ꢓꢒ
" ꢊꢑꢊꢉ ꢘꢈꢞꢅ-ꢈ (ꢘ (% ꢆꢇ%ꢞ ꢆꢗꢗꢇ(ꢊ% ꢘꢞ
ꢀꢎꢀ
ꢎꢈꢊ #ꢉꢗꢅꢘ ,ꢞꢛꢘ 'ꢆꢉ ꢚꢊ ꢅ%ꢊ$ ꢆ% ꢆ -ꢊꢉꢊꢛꢆꢇ ꢗꢅꢛꢗꢞ%ꢊ (ꢉꢗꢅꢘ ꢞꢛ
ꢘꢈꢊ ꢄꢋꢌꢍꢎ 'ꢆꢉ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ ꢅ%ꢊ %ꢞꢙꢊ ꢞ+ ꢘꢈꢊ%ꢊ
(ꢉꢗꢅꢘ% +ꢞꢛ %ꢗꢊ'(ꢆꢇ +ꢅꢉ'ꢘ(ꢞꢉ%ꢒ ꢎꢈꢊ 'ꢅꢛꢛꢊꢉꢘ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ
(ꢉꢗꢅꢘ% ꢘꢞ ꢘꢈ(% ꢅꢉꢇꢆꢘ'ꢈꢊ$ ꢗꢞꢛꢘ 'ꢆꢉ ꢚꢊ ꢛꢊꢆ$ ꢚ& ꢘꢈꢊ ꢀ,ꢋ ꢚ&
ꢛꢊꢆ$(ꢉ- ꢘꢈꢊ #, ꢛꢊ-(%ꢘꢊꢛ ꢏ+ꢞꢛ ꢘꢈꢊ %ꢘꢆꢘꢊ% ꢞ+ #,ꢕ ꢜ #,6ꢐꢒ ꢌ ꢈ(-ꢈ
(ꢉꢗꢅꢘ %(-ꢉꢆꢇ ꢆꢘ ꢘꢈꢊ #,ꢉ ꢗ(ꢉ ꢛꢊ%ꢅꢇꢘ% (ꢉ ꢆ ꢇꢞ-(' CꢔD (ꢉ ꢘꢈꢊ #,ꢍNꢉO
ꢚ(ꢘ ꢗꢞ%(ꢘ(ꢞꢉ" ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ #, ꢛꢊ-(%ꢘꢊꢛꢒ 9(3ꢊꢝ(%ꢊ" ꢆ CꢇꢞꢝD (ꢉꢗꢅꢘ
%(-ꢉꢆꢇ ꢆꢘ ꢘꢈꢊ #,ꢉ ꢗ(ꢉ ꢛꢊ%ꢅꢇꢘ% (ꢉ ꢆ ꢇꢞ-(' CꢕD (ꢉ ꢘꢈꢊ #,ꢍNꢉO ꢚ(ꢘ
ꢗꢞ%(ꢘ(ꢞꢉ" ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ #, ꢛꢊ-(%ꢘꢊꢛꢒ
ꢁ f
- RXC and TXC (External) Frequency - via
RTX
IP2, IP3, IP4, and IP5
ꢎꢈ(% %ꢗꢊ' ꢗꢇꢆ'ꢊ% ꢇ(ꢙ(ꢘ% ꢞꢉ ꢚꢞꢘꢈ ꢘꢈꢊ ꢔ5 ꢆꢉ$ ꢔ/5 ꢊ!ꢘꢊꢛꢉꢆꢇ
%(-ꢉꢆꢇ% ꢘꢈꢆꢘ ꢆꢛꢊ ꢘꢞ ꢚꢊ ꢅ%ꢊ$ ꢘꢞ 'ꢇꢞ'3 ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ% ꢆꢉ$
ꢍꢊ'ꢊ(ꢑꢊꢛ%ꢒ #+ ꢘꢈꢊ ꢅ%ꢊꢛ ꢝ(%ꢈꢊ% ꢘꢞ ꢅ%ꢊ ꢆ ꢔ5 'ꢇꢞ'3" ꢈꢊ.%ꢈꢊ
'ꢆꢉ ꢞꢉꢇ& ꢆꢗꢗꢇ& ꢆ %(-ꢉꢆꢇ ꢝ(ꢘꢈ +ꢛꢊEꢅꢊꢉ'(ꢊ% ꢅꢗ ꢘꢞ ꢔꢒꢕ ꢁ8Iꢒ
ꢎꢈ(% (ꢉꢗꢅꢘ ꢝ(ꢇꢇ ꢛꢊ%ꢅꢇꢘ% (ꢉ ꢆ ꢚ(ꢘ ꢛꢆꢘꢊ ꢞ+ ꢔ ꢁꢚꢗ% ꢏ%ꢊꢊ 2!ꢆꢙꢗꢇꢊ
ꢀꢐꢒ #+ ꢘꢈꢊ ꢅ%ꢊꢛ ꢝ(%ꢈꢊ% ꢘꢞ ꢅ%ꢊ ꢆ ꢔ/5 'ꢇꢞ'3" ꢈꢊ.%ꢈꢊ 'ꢆꢉ ꢞꢉꢇ&
ꢆꢗꢗꢇ& ꢆ %(-ꢉꢆꢇ ꢝ(ꢘꢈ +ꢛꢊEꢅꢊꢉ'(ꢊ% ꢅꢗ ꢘꢞ ꢓꢒꢕ ꢁ8Iꢒ ꢃ(ꢉ'ꢊ ꢘꢈ(%
%(-ꢉꢆꢇ (% ꢆ ꢔ/5 %(-ꢉꢆꢇ" ꢘꢈ(% ꢝ(ꢇꢇ ꢛꢊ%ꢅꢇꢘ (ꢉ ꢆ ꢚ(ꢘ ꢛꢆꢘꢊ ꢞ+
ꢔꢓ63ꢚꢗ%ꢒ
E.1 Alternate Functions for the Input Port
Table 17 $ꢊ%'ꢛ(ꢚꢊ% ꢘꢈꢊ ꢆꢇꢘꢊꢛꢉꢆꢘꢊ ꢅ%ꢊ% +ꢞꢛ ꢘꢈꢊ (ꢉꢗꢅꢘ ꢗ(ꢉ%"
%ꢅ'ꢈ ꢆ% 'ꢇꢞ'3 (ꢉꢗꢅꢘ% ꢆꢉ$ $ꢆꢘꢆ +ꢇꢞꢝ 'ꢞꢉꢘꢛꢞꢇ %(-ꢉꢆꢇ% ꢆꢉ$
(ꢉ'ꢇꢅ$ꢊ% ꢆ ꢚꢛ(ꢊ+ %ꢅꢙꢙꢆꢛ& ꢆ% ꢈꢞꢝ ꢘꢞ ꢗꢛꢞ-ꢛꢆꢙ ꢘꢈꢊ ꢆꢇꢘꢊꢛꢉꢆꢘꢊ
+ꢅꢉ'ꢘ(ꢞꢉꢒ ꢌ ꢛꢊꢆ$ ꢞ+ ꢘꢈꢊ #, ꢛꢊ-(%ꢘꢊꢛ% ꢝ(ꢇꢇ %ꢈꢞꢝ ꢘꢈꢊ ꢇꢞ-(' %ꢘꢆꢘꢊ
ꢆꢘ ꢘꢈꢊ ꢗ(ꢉ" ꢛꢊ-ꢆꢛ$ꢇꢊ%% ꢞ+ (ꢘ% ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ +ꢅꢉ'ꢘ(ꢞꢉꢒ
#ꢉ %ꢅꢙꢙꢆꢛ&" ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢎ(ꢙ(ꢉ- ꢀꢞꢉꢘꢛꢞꢇ ꢚꢇꢞ'3 -(ꢑꢊ% ꢘꢈꢊ
ꢅ%ꢊꢛ ꢘꢈꢊ ꢆꢚ(ꢇ(ꢘ& ꢘꢞ -ꢊꢉꢊꢛꢆꢘꢊ ꢑ(ꢛꢘꢅꢆꢇꢇ& ꢆꢉ& ꢚꢆꢅ$ ꢛꢆꢘꢊ ꢘꢈꢆꢘ ꢈꢊ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
/ꢔ
XR88C681
Input Port
Alternate Function(s)
Approach to Program Alternate Functions
#,ꢕ
ꢜCTSA4 ꢀꢇꢊꢆꢛ ꢘꢞ ꢃꢊꢉ$ ꢏꢀꢎꢃꢐ (ꢉꢗꢅꢘ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ ꢌꢒ #,ꢕ 'ꢆꢉ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢜꢀꢎꢃꢌ
7ꢞꢘꢊ4 ꢘꢈ(% (ꢉꢗꢅꢘ (% ꢌ'ꢘ(ꢑꢊ 9ꢞꢝ" +ꢞꢛ ꢘꢈꢊ ꢀꢎꢃ +ꢅꢉ'ꢘ(ꢞꢉ (ꢉꢗꢅꢘ ꢚ& %ꢊꢘꢘ(ꢉ- ꢁꢍꢓꢌN<O Jꢔꢒ ꢞꢛ ꢆ ꢙꢞꢛꢊ $ꢊꢘꢆ(ꢇꢊ$
$(%'ꢅ%%(ꢞꢉ ꢞꢉ ꢘꢈ(% +ꢅꢉ'ꢘ(ꢞꢉ" ꢗꢇꢊꢆ%ꢊ %ꢊꢊ Section
G.3.
#,ꢔ
#,ꢓ
ꢜCTSB4 ꢀꢇꢊꢆꢛ ꢘꢞ ꢃꢊꢉ$ ꢏꢀꢎꢃꢐ (ꢉꢗꢅꢘ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ *ꢒ #,ꢔ 'ꢆꢉ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢜꢀꢎꢃ*
7ꢞꢘꢊ4 ꢎꢈ(% (ꢉꢗꢅꢘ (% ꢌ'ꢘ(ꢑꢊ 9ꢞꢝ +ꢞꢛ ꢘꢈꢊ ꢀꢎꢃ +ꢅꢉ'ꢘ(ꢞꢉ (ꢉꢗꢅꢘ ꢚ& %ꢊꢘꢘ(ꢉ- ꢁꢍꢓ*N<O Jꢔꢒ ꢞꢛ ꢆ ꢙꢞꢛꢊ $ꢊꢘꢆ(ꢇꢊ$
$(%'ꢅ%%(ꢞꢉ ꢞꢉ ꢘꢈ(% +ꢅꢉ'ꢘ(ꢞꢉ" ꢗꢇꢊꢆ%ꢊ %ꢊꢊ Section G.3.
CT_EX4 ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ 2!ꢘꢊꢛꢉꢆꢇ ꢀꢇꢞ'3 #ꢉꢗꢅꢘꢒ
#,ꢓ 'ꢆꢉ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢊ!ꢘꢊꢛꢉꢆꢇ
'ꢇꢞ'3 (ꢉꢗꢅꢘ +ꢞꢛ ꢘꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢚ& %ꢊꢘꢘ(ꢉ-
ꢌꢀꢍN/4<O J Nꢕ" ꢕ" ꢕOꢒ ꢞꢛ ꢆ ꢙꢞꢛꢊ $ꢊꢘꢆ(ꢇꢊ$ $(%'ꢅ%ꢜ
%(ꢞꢉ (ꢉꢘꢞ ꢘꢈꢊ ꢊ++ꢊ'ꢘ ꢞ+ ꢘꢈ(% ꢆ'ꢘ(ꢞꢉ ꢗꢇꢊꢆ%ꢊ %ꢊꢊ Section
D.2
RXCB4 2!ꢘꢊꢛꢉꢆꢇ ꢀꢇꢞ'3 (ꢉꢗꢅꢘ +ꢞꢛ ꢍꢊ'ꢊ(ꢑꢊꢛ
ꢀꢈꢆꢉꢉꢊꢇ *
#,ꢓ 'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ
ꢊ!ꢘꢊꢛꢉꢆꢇ 'ꢇꢞ'3 (ꢉꢗꢅꢘ +ꢞꢛ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢞ+ ꢀꢈꢆꢉꢉꢊꢇ *
ꢚ& %ꢊꢘꢘ(ꢉ- ꢀꢃꢍ*N>4<O J Nꢔ" ꢔ" ꢔ" ꢕO +ꢞꢛ ꢘꢈꢊ ꢔ/5
ꢀꢇꢞ'3" ꢞꢛ ꢀꢃꢍ*N>4<O J Nꢔ" ꢔ" ꢔ" ꢔO +ꢞꢛ ꢘꢈꢊ ꢔ5 ꢀꢇꢞ'3ꢒ
#,1
#,<
#,6
TXCA: 2!ꢘꢊꢛꢉꢆꢇ ꢀꢇꢞ'3 (ꢉꢗꢅꢘ +ꢞꢛ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ
ꢀꢈꢆꢉꢉꢊꢇ ꢌ
#,1 'ꢆꢉ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢊ!ꢘꢊꢛꢉꢆꢇ
'ꢇꢞ'3 (ꢉꢗꢅꢘ +ꢞꢛ ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢞ+ ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢚ& %ꢊꢘꢜ
ꢘ(ꢉ- ꢀꢃꢍꢌN14ꢕO J Nꢔ" ꢔ" ꢔ" ꢕO +ꢞꢛ ꢘꢈꢊ ꢔ/5 ꢀꢇꢞ'3" ꢞꢛ
ꢀꢃꢍꢌN14ꢕO J Nꢔ" ꢔ" ꢔ" ꢔO +ꢞꢛ ꢘꢈꢊ ꢔ5 ꢀꢇꢞ'3ꢒ
RXCA4 2!ꢘꢊꢛꢉꢆꢇ ꢀꢇꢞ'3 (ꢉꢗꢅꢘ +ꢞꢛ ꢍꢊ'ꢊ(ꢑꢊꢛ
ꢀꢈꢆꢉꢉꢊꢇ ꢌ
#,< 'ꢆꢉ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢊ!ꢘꢊꢛꢉꢆꢇ
'ꢇꢞ'3 (ꢉꢗꢅꢘ +ꢞꢛ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢞ+ ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢚ& %ꢊꢘꢘ(ꢉ-
ꢀꢃꢍꢌN>4<O J Nꢔ" ꢔ" ꢔ" ꢕO +ꢞꢛ ꢘꢈꢊ ꢔ/5 ꢀꢇꢞ'3" ꢞꢛ
ꢀꢃꢍꢌN>4<O J Nꢔ" ꢔ" ꢔ" ꢔO +ꢞꢛ ꢘꢈꢊ ꢔ5 ꢀꢇꢞ'3ꢒ
TXCB4 2!ꢘꢊꢛꢉꢆꢇ ꢀꢇꢞ'3 (ꢉꢗꢅꢘ +ꢞꢛ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ
ꢀꢈꢆꢉꢉꢊꢇ *
#,6 'ꢆꢉ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ +ꢅꢉ'ꢘ(ꢞꢉ ꢆ% ꢘꢈꢊ ꢊ!ꢘꢊꢛꢉꢆꢇ
'ꢇꢞ'3 (ꢉꢗꢅꢘ +ꢞꢛ ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢞ+ ꢀꢈꢆꢉꢉꢊꢇ * ꢚ& %ꢊꢘꢜ
ꢘ(ꢉ- ꢀꢃꢍ*N14ꢕO J Nꢔ" ꢔ" ꢔ" ꢕO +ꢞꢛ ꢘꢈꢊ ꢔ/5 ꢀꢇꢞ'3" ꢞꢛ
ꢀꢃꢍ*N14ꢕO J Nꢔ" ꢔ" ꢔ" ꢔO +ꢞꢛ ꢘꢈꢊ ꢔ5 ꢀꢇꢞ'3ꢒ
Table 21. Listing of Alternate Function for the Input Port
E.2 Input Port Configuration Registers (IPCR)
ꢀꢈꢆꢉ-ꢊ ꢞ+ %ꢘꢆꢘꢊ $ꢊꢘꢊ'ꢘꢞꢛ% ꢆꢛꢊ ꢗꢛꢞꢑ($ꢊ$ +ꢞꢛ (ꢉꢗꢅꢘ ꢗ(ꢉ% #,ꢕ ꢘꢈꢛꢞꢅ-ꢈ #,1ꢒ ꢎꢈꢊ%ꢊ (ꢉꢗꢅꢘ% ꢆꢛꢊ %ꢆꢙꢗꢇꢊ$ ꢚ& ꢘꢈꢊ 1=ꢒ<38I ꢞꢅꢘꢗꢅꢘ
ꢞ+ ꢘꢈꢊ *ꢍ0 ꢏꢓꢒ<3ꢚꢗ% ! ꢔ/ꢐꢒ ꢌ ꢈ(-ꢈꢜꢘꢞꢜꢇꢞꢝ ꢞꢛ ꢇꢞꢝꢜꢘꢞꢜꢈ(-ꢈ ꢘꢛꢆꢉ%(ꢘ(ꢞꢉ ꢆꢘ ꢘꢈꢊ%ꢊ (ꢉꢗꢅꢘ ꢇꢆ%ꢘ(ꢉ- ꢆꢘ ꢇꢊꢆ%ꢘ ꢘꢝꢞ 'ꢇꢞ'3 ꢗꢊꢛ(ꢞ$%
ꢏꢆꢗꢗꢛꢞ!(ꢙꢆꢘꢊꢇ& 6ꢕ• %ꢐ ꢝ(ꢇꢇ -ꢅꢆꢛꢆꢉꢘꢊꢊ ꢘꢈꢆꢘ ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- ꢚ(ꢘ (ꢉ ꢘꢈꢊ (ꢉꢗꢅꢘ ꢗꢞꢛꢘ 'ꢈꢆꢉ-ꢊ ꢛꢊ-(%ꢘꢊꢛ ꢏ#,ꢀꢍꢐ ꢝ(ꢇꢇ ꢚꢊ %ꢊꢘ"
ꢆꢇꢘꢈꢞꢅ-ꢈ (ꢘ ꢙꢆ& ꢚꢊ %ꢊꢘ ꢚ& ꢆ 'ꢈꢆꢉ-ꢊ ꢞ+ %ꢘꢆꢘꢊ ꢆ% %ꢈꢞꢛꢘ ꢆ% ꢓ6• %ꢒ ꢎꢈꢊ ꢚ(ꢘ +ꢞꢛꢙꢆꢘ ꢞ+ ꢘꢈꢊ #,ꢀꢍ +ꢞꢇꢇꢞꢝ%ꢒ ꢎꢈꢊ %ꢘꢆꢘꢅ% ꢚ(ꢘ% (ꢉ ꢘꢈꢊ
#,ꢀꢍ ꢏ#,ꢀꢍN>4<Oꢐ ꢆꢛꢊ 'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ ꢛꢊ-(%ꢘꢊꢛ (% ꢛꢊꢆ$ ꢚ& ꢘꢈꢊ ꢀ,ꢋꢒ ꢌꢉ& 'ꢈꢆꢉ-ꢊ ꢞ+ %ꢘꢆꢘꢊ 'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ
-ꢊꢉꢊꢛꢆꢘꢊ ꢆꢉ (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢑ(ꢆ ꢘꢈꢊ C#ꢉꢗꢅꢘ ,ꢞꢛꢘ ꢀꢈꢆꢉ-ꢊ ꢞ+ ꢃꢘꢆꢘꢊD (ꢉꢘꢊꢛꢛꢅꢗꢘꢒ
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
IP3
Bit 2
IP2
Bit 1
IP1
Bit 0
IP0
Delta IP3
Delta IP2
Delta IP1
Delta IP0
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 9ꢞꢝ
ꢔ J 8(-ꢈ
ꢕ J 9ꢞꢝ
ꢔ J 8(-ꢈ
ꢕ J 9ꢞꢝ
ꢔ J 8(-ꢈ
ꢕ J 9ꢞꢝ
ꢔ J 8(-ꢈ
Table 22. Input Port Configuration Register - IPCR
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
/ꢓ
XR88C681
#ꢉ ꢞꢛ$ꢊꢛ ꢘꢞ ꢊꢉꢆꢚꢇꢊ ꢘꢈꢊ C#ꢉꢗꢅꢘ ,ꢞꢛꢘ ꢀꢈꢆꢉ-ꢊ ꢞ+ ꢃꢘꢆꢘꢊD (ꢉꢘꢊꢛꢛꢅꢗꢘ" ꢞꢉꢊ ꢙꢅ%ꢘ $ꢞ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ-ꢒ
ꢁ Bꢛ(ꢘꢊ ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ $ꢆꢘꢆ ꢘꢞ ꢘꢈꢊ ꢇꢞꢝꢊꢛ ꢉ(ꢚꢚꢇꢊ ꢞ+ ꢌꢀꢍꢒ ꢎꢈꢊ ꢚ(ꢘ +ꢞꢛꢙꢆꢘ% +ꢞꢛ ꢌꢀꢍ (% ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ Table 23ꢒ Please
note that the applicable bits, within the ACR register, are shaded.
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
BRG Set
Select
Counter/Timer Mode and Source
Delta IP3
Interrupt
Delta IP2
Interrupt
Delta IP1
Interrupt
Delta IP0
Interrupt
ꢕ J ꢃꢊꢘꢔ
ꢔ J ꢃꢊꢘꢓ
ꢃꢊꢊ Table 7
ꢕ J ꢂ
ꢔ J ꢂ7
ꢕ J ꢂ
ꢔ J ꢂ7
ꢕ J ꢂ
ꢔ J ꢂ7
ꢕ J ꢂ
ꢔ J ꢂ7
Table 23. ACR- Auxiliary Control Register
ꢁ ꢃꢊꢘꢘ(ꢉ- #ꢁꢍN>Oꢒ
Note: This “two-tiered” interrupt enabling/disabling approach, for the “Input Change of State” interrupt allows tremendous flexibility
for the user. Setting or clearing the bits in ACR[3:0] allows the user to specify exactly which Input Port pins to be enabled (or
disabled) for generating the “Input Port Change of State” interrupt. Setting or clearing IMR[7] allows the user to “globally”
enable or disable this interrupt.
ꢎꢈꢊ ꢅꢗꢗꢊꢛ ꢉ(ꢚꢚꢇꢊ ꢞ+ ꢘꢈꢊ #,ꢀꢍ ꢝ(ꢇꢇ (ꢉ$('ꢆꢘꢊ ꢝꢈ('ꢈ ꢞ+ ꢘꢈꢊ +ꢞꢅꢛ
(ꢉꢗꢅꢘ ꢗ(ꢉ% ꢊ!ꢗꢊꢛ(ꢊꢉ'ꢊ$ ꢘꢈꢊ Cꢀꢈꢆꢉ-ꢊ ꢞ+ ꢃꢘꢆꢘꢊꢒD ꢎꢈꢊ ꢇꢞꢝꢊꢛ
ꢉ(ꢚꢚꢇꢊ ꢞ+ ꢘꢈꢊ #,ꢀꢍ 'ꢞꢉꢘꢆ(ꢉ% ꢘꢈꢊ ꢗꢛꢊ%ꢊꢉꢘ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ%ꢊ
(ꢉꢗꢅꢘ ꢗ(ꢉ%ꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢝꢈꢊꢉ ꢛꢊꢆ$(ꢉ- ꢘꢈꢊ #,ꢀꢍ" (ꢉ
ꢛꢊ%ꢗꢞꢉ%ꢊ ꢘꢞ ꢘꢈꢊ Cꢀꢈꢆꢉ-ꢊ ꢞ+ ꢃꢘꢆꢘꢊD (ꢉꢘꢊꢛꢛꢅꢗꢘ" ꢘꢈꢊ ꢀ,ꢋ ꢝ(ꢇꢇ
$ꢊꢘꢊꢛꢙ(ꢉꢊ4
ꢍꢊ-(%ꢘꢊꢛ ꢏꢂ,ꢍꢐ" ꢆꢉ$ ꢘꢈꢊ ꢞꢅꢘꢗꢅꢘ ꢗꢞꢛꢘ ꢗ(ꢉ% ꢘꢈꢊꢙ%ꢊꢇꢑꢊ%ꢒ
ꢎꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ ꢂ,ꢍ ꢆꢛꢊ 'ꢞꢙꢗꢇꢊꢙꢊꢉꢘ% ꢞ+ ꢘꢈꢊ ꢆ'ꢘꢅꢆꢇ
%ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ%ꢒ
ꢞꢛ 2!ꢆꢙꢗꢇꢊ4
#+ ꢘꢈꢊ ꢚ(ꢘ ꢂ,ꢍN6O (% %ꢊꢘ ꢘꢞ ꢆ ꢇꢞ-(' CꢔD" ꢘꢈ(% ꢝ(ꢇꢇ ꢛꢊ%ꢅꢇꢘ (ꢉ ꢘꢈꢊ
ꢂ,6 ꢗ(ꢉ ꢚꢊ(ꢉ- ꢆꢘ ꢆ ꢇꢞ-(' CꢕDꢒ 9(3ꢊꢝ(%ꢊ" (+ ꢘꢈꢊ ꢚ(ꢘ ꢂ,ꢍN6O (%
%ꢊꢘ ꢘꢞ ꢆ ꢇꢞ-(' CꢕD" ꢘꢈ(% ꢛꢊ%ꢅꢇꢘ% (ꢉ ꢘꢈꢊ ꢂ,6 ꢗ(ꢉ ꢚꢊ(ꢉ- ꢆꢘ ꢆ ꢇꢞ-('
CꢔDꢒ ꢎꢈꢊ ꢞꢘꢈꢊꢛ ꢘꢈ(ꢉ- ꢘꢈꢆꢘ ꢙꢆ3ꢊ% ꢗꢛꢞ-ꢛꢆꢙꢙ(ꢉ- ꢘꢈꢊ ꢗꢆꢛꢆꢇꢇꢊꢇ
ꢗꢞꢛꢘ ꢆ ꢇ(ꢘꢘꢇꢊ ꢞ$$ (% ꢘꢈꢊ ꢗꢛꢞ'ꢊ$ꢅꢛꢊ ꢘꢈꢆꢘ ꢞꢉꢊ ꢙꢅ%ꢘ ꢅ%ꢊ ꢘꢞ
ꢆ''ꢞꢙꢗꢇ(%ꢈ ꢘꢈ(% +ꢊꢆꢘꢒ Bꢈꢊꢉ ꢝꢛ(ꢘ(ꢉ- ꢘꢞ ꢘꢈ(% ꢗꢆꢛꢆꢇꢇꢊꢇ ꢞꢅꢘꢗꢅꢘ
ꢗꢞꢛꢘ" ꢞꢉꢊ ꢙꢅ%ꢘ (ꢉꢑꢞ3ꢊ ꢞꢉꢊ ꢞ+ ꢘꢈꢊ ꢘꢝꢞ ꢆ$$ꢛꢊ%% ꢘꢛ(--ꢊꢛꢊ$
'ꢞꢙꢙꢆꢉ$%4 ꢃ2ꢎ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃ ꢆꢉ$ ꢀ92ꢌꢍ
ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃꢒ It is important to note that when
invoking the “SET OUTPUT PORT BITS” command, the
user is setting the bits (to logic “1”) in the OPRꢒ 8ꢞꢝꢊꢑꢊꢛ"
ꢘꢈ(% ꢆ'ꢘ(ꢞꢉ ꢛꢊ%ꢅꢇꢘ% (ꢉ %ꢊꢘꢘ(ꢉ- ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- ꢂꢅꢘꢗꢅꢘ
,ꢞꢛꢘ ꢗ(ꢉ% ꢘꢞ ꢇꢞ-(' CꢕDL $ꢅꢊ ꢘꢞ ꢘꢈꢊ 'ꢞꢙꢗꢇꢊꢙꢊꢉꢘꢆꢛ&
ꢛꢊꢇꢆꢘ(ꢞꢉ%ꢈ(ꢗ ꢚꢊꢘꢝꢊꢊꢉ ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ% ꢆꢉ$
ꢘꢈꢊ ꢚ(ꢘ% (ꢉ ꢘꢈꢊ ꢂ,ꢍꢒ 9(3ꢊꢝ(%ꢊ" ꢝꢈꢊꢉ ꢘꢈꢊ ꢀ92ꢌꢍ ꢂꢋꢎ,ꢋꢎ
,ꢂꢍꢎ *#ꢎꢃ 'ꢞꢙꢙꢆꢉ$ (% (ꢉꢑꢞ3ꢊ$" ꢘꢈꢊ %ꢗꢊ'(+(ꢊ$ ꢚ(ꢘ%"
ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢂ,ꢍ ꢆꢛꢊ C'ꢇꢊꢆꢛꢊ$D ꢘꢞ ꢇꢞ-(' CꢕDꢒ 8ꢞꢝꢊꢑꢊꢛ" ꢘꢈꢊ
'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ% ꢆꢛꢊ %ꢊꢘ ꢘꢞ ꢘꢈꢊ ꢇꢞ-(' CꢔD
%ꢘꢆꢘꢊꢒ
ꢁ ꢎꢈꢊ (ꢉꢗꢅꢘ ꢗ(ꢉꢏ%ꢐ ꢘꢈꢆꢘ ꢘꢞ--ꢇꢊ$ꢒ
ꢁ ꢎꢈꢊ +(ꢉꢆꢇ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ 'ꢈꢆꢉ-(ꢉ- (ꢉꢗꢅꢘ ꢗ(ꢉꢒ
E.3 28 Pin Packaged DUARTs
ꢎꢈꢊ ꢓ= ꢗ(ꢉ ꢗꢆ'3ꢆ-ꢊ$ ꢄꢋꢌꢍꢎ% 'ꢞꢙꢊ ꢝ(ꢘꢈ ꢞꢉꢇ& ꢞꢉꢊ (ꢉꢗꢅꢘ
ꢗꢞꢛꢘ ꢗ(ꢉ" #,ꢓꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢘꢈꢊ ꢞꢉꢇ& ꢆꢇꢘꢊꢛꢉꢆꢘ(ꢑꢊ +ꢅꢉ'ꢘ(ꢞꢉ% ꢘꢈꢆꢘ
ꢆꢛꢊ ꢆꢑꢆ(ꢇꢆꢚꢇꢊ ꢘꢞ ꢘꢈꢊ $ꢊꢑ('ꢊ ꢏꢑ(ꢆ ꢘꢈ(% (ꢉꢗꢅꢘ ꢗꢞꢛꢘ ꢗ(ꢉꢐ ꢆꢛꢊ
ꢀꢎF25 ꢏꢀ.ꢎ 2!ꢘꢊꢛꢉꢆꢇ ꢀꢇꢞ'3 #ꢉꢗꢅꢘꢐ ꢆꢉ$ ꢍ5ꢀ* ꢏ2!ꢘꢊꢛꢉꢆꢇ
ꢀꢇꢞ'3 (ꢉꢗꢅꢘ +ꢞꢛ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢀꢈꢆꢉꢉꢊꢇ *ꢐꢒ
F. OUTPUT PORT
ꢎꢈꢊ ꢄꢋꢌꢍꢎ 'ꢞꢉ%(%ꢘ% ꢞ+ ꢆꢉ = ꢚ(ꢘ ꢗꢆꢛꢆꢇꢇꢊꢇ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘꢒ ꢎꢈꢊ
ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ 'ꢆꢉ ꢚꢊ ꢅ%ꢊ$ ꢆ% ꢆ -ꢊꢉꢊꢛꢆꢇ ꢗꢅꢛꢗꢞ%ꢊ ꢞꢅꢘꢗꢅꢘ ꢞꢛ
'ꢆꢉ ꢚꢊ ꢅ%ꢊ$ +ꢞꢛ ꢞꢅꢘꢗꢅꢘ ꢘ(ꢙ(ꢉ- ꢆꢉ$ %ꢘꢆꢘꢅ% %(-ꢉꢆꢇ% ꢚ&
ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊꢇ& ꢗꢛꢞ-ꢛꢆꢙꢙ(ꢉ- ꢞ+ ꢘꢈꢊ ꢙꢞ$ꢊ ꢛꢊ-(%ꢘꢊꢛ% ꢏꢁꢍꢔꢌ"
* ꢆꢉ$ ꢁꢍꢓꢌ" *ꢐ ꢆꢉ$ ꢆꢇ%ꢞ ꢘꢈꢊ ꢞꢅꢘꢗꢅꢘ ꢗꢞꢛꢘ 'ꢞꢉ+(-ꢅꢛꢆꢘ(ꢞꢉ
ꢛꢊ-(%ꢘꢊꢛ" ꢂ,ꢀꢍꢒ Bꢈꢊꢉ ꢅ%ꢊ$ ꢘꢞ ꢞꢅꢘꢗꢅꢘ %ꢘꢆꢘꢅ% %(-ꢉꢆꢇ% ꢘꢈꢊ
ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ% ꢆꢛꢊ ꢞꢗꢊꢉ $ꢛꢆ(ꢉ" ꢝꢈ('ꢈ ꢆꢇꢇꢞꢝ% ꢘꢈꢊ(ꢛ ꢅ%ꢊ (ꢉ
ꢆ ꢝ(ꢛꢊ ꢂꢍ (ꢉꢘꢊꢛꢛꢅꢗꢘ %'ꢈꢊꢙꢊꢒ
ꢎꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢊꢆ'ꢈ ꢚ(ꢘ ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢂ,ꢍ" +ꢞꢇꢇꢞꢝ(ꢉ- ꢆ ,ꢞꢝꢊꢛꢜꢞꢉ
ꢍꢊ%ꢊꢘ ꢏ,ꢂꢍꢐ" (% ꢆꢇꢇ CꢕDꢒ ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢊꢆ'ꢈ
ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ" +ꢞꢇꢇꢞꢝ(ꢉ- ꢆ ,ꢂꢍ (% ꢇꢞ-(' CꢔDꢒ
,ꢛꢞ-ꢛꢆꢙꢙ(ꢉ- ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ (% ꢆ ꢇ(ꢘꢘꢇꢊ $(++ꢊꢛꢊꢉꢘ +ꢛꢞꢙ ꢘꢈꢊ
'ꢞꢉꢑꢊꢉꢘ(ꢞꢉꢆꢇ ꢝꢛ(ꢘꢊ% ꢘꢞ ꢆ ꢘ&ꢗ('ꢆꢇ ꢗꢆꢛꢆꢇꢇꢊꢇ ꢗꢞꢛꢘ ꢞꢛ ꢘꢈꢊ $ꢆꢘꢆ
ꢚꢅ%ꢒ ꢎꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ '(ꢛ'ꢅ(ꢘꢛ& 'ꢞꢉ%(%ꢘ% ꢞ+ ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ
ꢎꢈꢊ ꢚ(ꢘ% ꢞ+ ꢘꢈꢊ ꢂ,ꢍ 'ꢆꢉ ꢚꢊ %ꢊꢘ ꢆꢉ$ 'ꢇꢊꢆꢛꢊ$ (ꢉ$(ꢑ($ꢅꢆꢇꢇ&ꢒ ꢌ
ꢚ(ꢘ (% %ꢊꢘ ꢚ& ꢘꢈꢊ ꢆ$$ꢛꢊ%%ꢜꢘꢛ(--ꢊꢛꢊ$ Cꢃ2ꢎ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ
*#ꢎꢃD 'ꢞꢙꢙꢆꢉ$ ꢏ%ꢊꢊ Table 1ꢐ ꢝ(ꢘꢈ ꢘꢈꢊ ꢆ''ꢞꢙꢗꢆꢉ&(ꢉ-
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
/1
XR88C681
$ꢆꢘꢆ" ꢆꢘ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ%" %ꢗꢊ'(+&(ꢉ- ꢘꢈꢊ ꢚ(ꢘ%" ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢂ,ꢍ"
ꢘꢞ ꢚꢊ %ꢊꢘ ꢏ ꢔ J %ꢊꢘ" ꢕ J ꢉꢞ 'ꢈꢆꢉ-ꢊꢐꢒ ꢌ ꢚ(ꢘ (% 'ꢇꢊꢆꢛꢊ$ ꢚ& ꢘꢈꢊ
ꢆ$$ꢛꢊ%% ꢘꢛ(--ꢊꢛꢊ$ Cꢀ92ꢌꢍ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃD
'ꢞꢙꢙꢆꢉ$ ꢏ%ꢊꢊ Table 1ꢐ ꢝ(ꢘꢈ ꢘꢈꢊ ꢆ''ꢞꢙꢗꢆꢉ&(ꢉ- $ꢆꢘꢆ" ꢆꢘ
ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ%" %ꢗꢊ'(+&(ꢉ- ꢘꢈꢊ ꢚ(ꢘ% ꢘꢞ ꢚꢊ ꢛꢊ%ꢊꢘ ꢏꢔ J 'ꢇꢊꢆꢛꢊ$" ꢕ
J ꢉꢞ 'ꢈꢆꢉ-ꢊꢐꢒ
ꢕ2 " ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- ꢚ(ꢘ" ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢂ,ꢍ (%
ꢔ/
ꢅꢉ'ꢈꢆꢉ-ꢊ$ꢒ
Bꢊ 'ꢞꢅꢇ$ %ꢘꢆꢘꢊ ꢘꢈ(% ꢆꢉꢞꢘꢈꢊꢛ ꢝꢆ& ꢆ%4 ꢞꢛ ꢊꢑꢊꢛ& CꢔD ꢘꢈꢆꢘ (%
ꢗꢛꢊ%ꢊꢉꢘ ꢞꢉ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ%" $ꢅꢛ(ꢉ- ꢘꢈꢊ ꢅ%ꢊ ꢞ+ ꢘꢈꢊ Cꢃ2ꢎ
ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃD 'ꢞꢙꢙꢆꢉ$" ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ-
ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ (% %ꢊꢘ ꢘꢞ ꢆ ꢇꢞ-(' CꢇꢞꢝDꢒ ꢌꢉ$ +ꢞꢛ ꢊꢑꢊꢛ& CꢕD ꢘꢈꢆꢘ
(% ꢗꢛꢊ%ꢊꢉꢘ ꢞꢉ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ%" $ꢅꢛ(ꢉ- ꢘꢈ(% 'ꢞꢙꢙꢆꢉ$" ꢘꢈꢊ
%ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ (% ꢅꢉ'ꢈꢆꢉ-ꢊ$ꢒ
F.1 Writing Data to the OPR/Output Port Pins
ꢞꢛ 2!ꢆꢙꢗꢇꢊ4
ꢌ% ꢙꢊꢉꢘ(ꢞꢉꢊ$ ꢊꢆꢛꢇ(ꢊꢛ" ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ ꢂ,ꢍ ꢆꢉ$
'ꢞꢉ%ꢊEꢅꢊꢉꢘꢇ&" ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ% (% 'ꢞꢉꢘꢛꢞꢇꢇꢊ$ ꢚ& ꢘꢝꢞ
Cꢌ$$ꢛꢊ%% ꢎꢛ(--ꢊꢛꢊ$D 'ꢞꢙꢙꢆꢉ$%ꢒ
ꢃꢅꢗꢗꢞ%ꢊ ꢘꢈꢆꢘ ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ ꢞ+ ꢘꢈꢊ ꢂ,ꢍ ꢆꢛꢊ ꢂ,ꢍN>4ꢕO J Nꢕ" ꢕ"
ꢕ" ꢕ" ꢔ" ꢔ" ꢔ" ꢔOꢒ 8ꢊꢉ'ꢊ" ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ%
ꢆꢛꢊ ꢆ% +ꢞꢇꢇꢞꢝ%4
ꢁ ꢃꢊꢘ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ *(ꢘ% ꢀꢞꢙꢙꢆꢉ$
ꢁ ꢀꢇꢊꢆꢛ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ *(ꢘ% ꢀꢞꢙꢙꢆꢉ$
Nꢂ,>" ꢂ,/" ꢂ,6" ꢂ,<" ꢂ,1" ꢂ,ꢓ" ꢂ,ꢔ" ꢂ,ꢕO J Nꢔ" ꢔ" ꢔ" ꢔ"
ꢕ" ꢕ" ꢕ" ꢕO
ꢎꢈꢊ ꢗꢛꢞ'ꢊ$ꢅꢛꢊ ꢆꢉ$ ꢊ++ꢊ'ꢘ ꢞ+ ꢅ%(ꢉ- ꢘꢈꢊ%ꢊ 'ꢞꢙꢙꢆꢉ$% ꢆꢛꢊ
$(%'ꢅ%%ꢊ$ (ꢉ Section F.1.1ꢒ
#+ ꢝꢊ ꢝꢛ(ꢘꢊ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- ꢘꢞ ꢄꢋꢌꢍꢎ ꢌ$$ꢛꢊ%% ꢕ2
L
ꢔ/
Nꢄ>"ꢒꢒꢒ"ꢄꢕO J Nꢔ" ꢔ" ꢔ" ꢔ" ꢕ" ꢕ" ꢕ" ꢕOL ꢘꢈꢊ ꢛꢊ%ꢅꢇꢘ(ꢉ- %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ
ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢍꢊ-(%ꢘꢊꢛ *(ꢘ% +ꢞꢇꢇꢞꢝ%4
F.1.1 Set Ouput Port Bits Command
ꢂ,ꢍN>4ꢕO J Nꢔ" ꢔ" ꢔ" ꢔ" ꢔ" ꢔ" ꢔ" ꢔOꢒ
ꢎꢈꢊ ꢆ'ꢘꢅꢆꢇ ꢗꢛꢞ'ꢊ$ꢅꢛꢊ ꢅ%ꢊ$ ꢘꢞ (ꢉꢑꢞ3ꢊ ꢘꢈꢊ Cꢃ2ꢎ ꢂꢋꢎ,ꢋꢎ
,ꢂꢍꢎ *#ꢎꢃD 'ꢞꢙꢙꢆꢉ$ (% ꢘꢈꢊ %ꢆꢙꢊ ꢆ% ꢝꢛ(ꢘ(ꢉ- ꢘꢈꢊ
'ꢞꢉꢘꢊꢉꢘ% ꢞꢉ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ% ꢏꢄ> ꢜ ꢄꢕꢐ ꢘꢞ ꢄꢋꢌꢍꢎ ꢌ$$ꢛꢊ%%
ꢀꢞꢉ%ꢊEꢅꢊꢉꢘꢇ&" ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ% ꢆꢛꢊ ꢆ%
+ꢞꢇꢇꢞꢝ%4
Nꢂ,>" ꢂ,/" ꢂ,6" ꢂ,<" ꢂ,1" ꢂ,ꢓ" ꢂ,ꢔ" ꢂ,ꢕO J Nꢕ" ꢕ" ꢕ" ꢕ"
ꢕ" ꢕ" ꢕ" ꢕO
ꢕ2 +ꢞꢛ ꢏꢂ,> ꢜ ꢂ,ꢕꢐꢒ ꢞꢛ ꢊꢑꢊꢛ& CꢔD ꢘꢈꢆꢘ ꢊ!(%ꢘ% ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ
ꢔ/
ꢇꢆꢘ'ꢈꢊ$ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ ꢄꢆꢘꢆ *ꢅ%" ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- ꢚ(ꢘ"
ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢂ,ꢍ (% %ꢊꢘ ꢘꢞ ꢆ ꢇꢞ-(' Cꢈ(-ꢈDꢒ ꢞꢛ ꢊꢑꢊꢛ& CꢕD ꢘꢈꢆꢘ (%
ꢗꢛꢊ%ꢊꢉꢘ ꢞꢉ ꢘꢈꢊ $ꢆꢘꢆ ꢚꢅ% ꢆꢉ$ (% ꢝꢛ(ꢘꢘꢊꢉ ꢘꢞ ꢄꢋꢌꢍꢎ ꢌ$$ꢛꢊ%%
ꢎꢈ(% ꢊ!ꢆꢙꢗꢇꢊ ꢞ+ ꢘꢈꢊ Cꢃ2ꢎ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃD
'ꢞꢙꢙꢆꢉ$ (% (ꢇꢇꢅ%ꢘꢛꢆꢘꢊ$ (ꢉ Figure 33ꢒ
ꢃꢘꢆꢘꢊ ꢞ+ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ,(ꢉ% ꢏꢂ,> ꢜ ꢂ,ꢕꢐ
#ꢉ(ꢘ(ꢆꢇ ꢂ,ꢍN>4ꢕO
ꢕ
ꢔ
ꢕ
ꢔ
ꢕ
ꢕ
ꢔ
ꢕ
ꢔ
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ꢔ
ꢔ
ꢔ
ꢕ
ꢕ
ꢕ
ꢕ
ꢄꢋꢌꢍꢎ ꢌ$$ꢛꢊ%% ꢕ2ꢈ
ꢔ
ꢔ
ꢕ
ꢄꢆꢘꢆ *ꢅ%" ꢄ> ꢜ ꢄꢕ
ꢔ
ꢔ
ꢔ
ꢔ
ꢔ
ꢔ
ꢔ
ꢔ
ꢕ
ꢕ
ꢕ
ꢕ
ꢕ
ꢕ
ꢕ
ꢕ
(ꢉꢆꢇ ꢂ,ꢍN>4ꢕO
Figure 33. Illustration of the “SET OUTPUT PORT BIT” Command and its Effect
on the Output Port Register and the State of the Output Port Pins.
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
/<
XR88C681
#ꢉ %ꢅꢙꢙꢆꢛ&" +ꢞꢛ ꢘꢈꢊ Cꢃ2ꢎ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃD
'ꢞꢙꢙꢆꢉ$L
ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- ꢂ,ꢍ ꢛꢊ-(%ꢘꢊꢛ ꢚ(ꢘ" ꢆꢉ$ (ꢉ
ꢘꢅꢛꢉ ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ (% ꢅꢉ'ꢈꢆꢉ-ꢊ$ꢒ
ꢞꢛ 2!ꢆꢙꢗꢇꢊ4
ꢄꢉ J ꢕL ꢛꢊ%ꢅꢇꢘ% (ꢉ ꢉꢞ 'ꢈꢆꢉ-ꢊ +ꢞꢛ ꢂ,ꢍNꢉO" ꢉꢞꢛ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ
ꢗ(ꢉ ꢂ,ꢉꢒ
ꢃꢅꢗꢗꢞ%ꢊ ꢘꢈꢆꢘ ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢍꢊ-(%ꢘꢊꢛ"
ꢂ,ꢍ J Nꢔ" ꢔ" ꢔ" ꢔ" ꢔ" ꢔ" ꢔ" ꢔOꢒ ꢀꢞꢉ%ꢊEꢅꢊꢉꢘꢇ&" ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ
ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ% ꢆꢛꢊ4
ꢄꢉ J ꢔL ꢛꢊ%ꢅꢇꢘ% (ꢉ ꢂ,ꢍNꢉO J CꢔD" ꢆꢉ$ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ" ꢂ,ꢉ J
CꢕD
Nꢂ,>" ꢂ,/" ꢂ,6" ꢂ,<" ꢂ,1" ꢂ,ꢓ" ꢂ,ꢔ" ꢂ,ꢕO J Nꢕ" ꢕ" ꢕ" ꢕ"
ꢕ" ꢕ" ꢕ" ꢕO
F.1.2 Clear Output Port Bits Command
#+ ꢝꢊ ꢝꢊꢛꢊ ꢘꢞ ꢝꢛ(ꢘꢊ Nꢄ>"ꢒꢒꢒ"ꢄꢕO J Nꢔ" ꢔ" ꢔ" ꢔ" ꢕ" ꢕ" ꢕ" ꢕO ꢘꢞ
ꢄꢋꢌꢍꢎ ꢆ$$ꢛꢊ%% ꢕ ꢔ/" ꢘꢈꢊ ꢛꢊ%ꢅꢇꢘ(ꢉ- 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ
ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢛꢊ-(%ꢘꢊꢛ ꢝ(ꢇꢇ ꢚꢊ4
ꢎꢈꢊ ꢗꢛꢞ'ꢊ$ꢅꢛꢊ +ꢞꢛ (ꢉꢑꢞ3(ꢉ- ꢘꢈ(% 'ꢞꢙꢙꢆꢉ$ (% ꢑꢊꢛ& %(ꢙ(ꢇꢆꢛ
ꢘꢞ ꢘꢈꢆꢘ +ꢞꢛ Cꢃ2ꢎ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃ ꢀꢂꢁꢁꢌ7ꢄDL
ꢂ,ꢍN>4ꢕO J Nꢕ" ꢕ" ꢕ" ꢕ" ꢔ" ꢔ" ꢔ" ꢔO
ꢊ!'ꢊꢗꢘ (ꢉ ꢘꢈꢆꢘ ꢘꢈꢊ ꢅ%ꢊꢛ ꢉꢞꢝ ꢝꢛ(ꢘꢊ% ꢘꢞ ꢄꢋꢌꢍꢎ ꢆ$$ꢛꢊ%% ꢕ
+ꢞꢛ Nꢂ,>"ꢒꢒꢒ"ꢂ,ꢕOꢒ
ꢔ/
ꢅꢛꢘꢈꢊꢛ" ꢘꢈꢊ ꢛꢊ%ꢅꢇꢘ(ꢉ- %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ% ꢝ(ꢇꢇ ꢚꢊ4
Nꢂ,>" ꢂ,/" ꢂ,6" ꢂ,<" ꢂ,1" ꢂ,ꢓ" ꢂ,ꢔ" ꢂ,ꢕO J Nꢔ" ꢔ" ꢔ" ꢔ"
ꢕ" ꢕ" ꢕ" ꢕO
ꢞꢛ ꢊꢑꢊꢛ& CꢔD ꢘꢈꢆꢘ (% Cꢝꢛ(ꢘꢘꢊꢉD ꢘꢞ ꢘꢈ(% ꢆ$$ꢛꢊ%%" ꢘꢈꢊ
'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- ꢚ(ꢘ (ꢉ ꢘꢈꢊ ꢂ,ꢍ ꢛꢊ-(%ꢘꢊꢛ (% %ꢊꢘ ꢘꢞ ꢆ ꢇꢞ-(' CꢇꢞꢝD
ꢆꢉ$ ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ" ꢂ,ꢉ (% %ꢊꢘ ꢘꢞ ꢆ
ꢇꢞ-(' Cꢈ(-ꢈDꢒ ꢞꢛ ꢊꢑꢊꢛ& CꢕD ꢘꢈꢆꢘ (% ꢝꢛ(ꢘꢘꢊꢉ ꢘꢞ ꢘꢈ(% ꢆ$$ꢛꢊ%%"
ꢎꢈ(% ꢊ!ꢆꢙꢗꢇꢊ ꢞ+ ꢘꢈꢊ Cꢃ2ꢎ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃD
'ꢞꢙꢙꢆꢉ$ (% (ꢇꢇꢅ%ꢘꢛꢆꢘꢊ$ (ꢉ Figure 34ꢒ
ꢃꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ,(ꢉ% ꢏꢂ,>ꢜꢂ,ꢕꢐ
#ꢉ(ꢘ(ꢆꢇ ꢂ,ꢍ N>4ꢕO
ꢔ
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ꢄꢆꢘꢆ *ꢅ%" ꢄ> ꢜ ꢄꢕ
ꢄꢋꢌꢍꢎ ꢌ$$ꢛꢊ%% ꢕ ꢈ
ꢔ
ꢔ
ꢔ
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(ꢉꢆꢇ ꢂ,ꢍ N>4ꢕO
ꢔ
ꢔ
ꢔ
ꢕ
Figure 34. Illustration of the “CLEAR OUTPUT PORT BIT” Command and its Effect
on the Output Port Register and the State of the Output Port Pins.
#ꢉ %ꢅꢙꢙꢆꢛ&" +ꢞꢛ ꢘꢈꢊ Cꢀ92ꢌꢍ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃD
'ꢞꢙꢙꢆꢉ$L
ꢄꢉ J ꢔ" ꢛꢊ%ꢅꢇꢘ% (ꢉ ꢂ,ꢍNꢉO J ꢕ" ꢆꢉ$ %ꢊꢘ% ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ-
ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ ꢘꢞ ꢆ ꢇꢞ-(' CꢔDꢒ
ꢄꢉ J ꢕ" ꢛꢊ%ꢅꢇꢘ% (ꢉ ꢉꢞ 'ꢈꢆꢉ-ꢊ +ꢞꢛ ꢂ,ꢍNꢉO ꢆꢉ$ ꢉꢞ 'ꢈꢆꢉ-ꢊ (ꢉ
ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ" ꢂ,ꢉꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
/6
XR88C681
F.2 Output Port Configuration Register (OPCR)
ꢎꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ% 'ꢆꢉ ꢚꢊ ꢅ%ꢊ$ ꢆ% 0ꢊꢉꢊꢛꢆꢇ ,ꢅꢛꢗꢞ%ꢊ ꢂꢅꢘꢗꢅꢘ ꢗ(ꢉ%" ꢞꢛ ꢘꢈꢊ& 'ꢆꢉ ꢚꢊ 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ ꢅ%ꢊ$ (ꢉ ꢆꢇꢘꢊꢛꢉꢆꢘꢊ
+ꢅꢉ'ꢘ(ꢞꢉ%ꢒ Table 24 ꢇ(%ꢘ% ꢘꢈꢊ ꢌꢇꢘꢊꢛꢉꢆꢘꢊ ꢅꢉ'ꢘ(ꢞꢉ% ꢞ+ ꢊꢆ'ꢈ ꢞ+ ꢘꢈꢊ ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ%ꢒ
Output Port
Alternate Function(s)
ꢂ,ꢕ
ꢜRTSA4 ꢍꢊEꢅꢊ%ꢘꢜꢘꢞꢜꢃꢊꢉ$ ꢏꢍꢎꢃꢐ ꢞꢅꢘꢗꢅꢘ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ ꢌꢒ 7ꢞꢘꢊ4 ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ (% ꢌ'ꢘ(ꢑꢊ
9ꢞꢝ +ꢞꢛ ꢘꢈꢊ ꢍꢎꢃ +ꢅꢉ'ꢘ(ꢞꢉꢒ
ꢂ,ꢔ
ꢂ,ꢓ
ꢜRTSB4 ꢍꢊEꢅꢊ%ꢘꢜꢘꢞꢜꢃꢊꢉ$ ꢏꢍꢎꢃꢐ ꢞꢅꢘꢗꢅꢘ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ *ꢒ 7ꢞꢘꢊ4 ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ (% ꢌ'ꢘ(ꢑꢊ
9ꢞꢝ +ꢞꢛ ꢘꢈꢊ ꢍꢎꢃ +ꢅꢉ'ꢘ(ꢞꢉꢒ
TXCA_16X Output4 ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢔ/5 ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢀꢇꢞ'3 ꢂꢅꢘꢗꢅꢘꢒ
TXCA_1X Output4 ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢔ5 ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢀꢇꢞ'3 ꢂꢅꢘꢗꢅꢘꢒ
RXCA_1X Outpuꢘ4 ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢔ5 ꢍꢊ'ꢊ(ꢑꢊꢛ ꢀꢇꢞ'3 ꢂꢅꢘꢗꢅꢘꢒ
ꢂ,1
TXCB_1X Output4 ꢀꢈꢆꢉꢉꢊꢇ * ꢔ5 ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢀꢇꢞ'3 ꢂꢅꢘꢗꢅꢘꢒ
RXCB_1X Output4 ꢀꢈꢆꢉꢉꢊꢇ * ꢔ5 ꢍꢊ'ꢊ(ꢑꢊꢛ ꢀꢇꢞ'3 ꢂꢅꢘꢗꢅꢘꢒ
C/T_RDY4 ꢎꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢍꢊꢆ$& ꢂꢅꢘꢗꢅꢘ +ꢞꢛ ꢀ.ꢎ Sꢔꢒ 7ꢞꢘꢊ4 ꢎꢈ(% ꢞꢅꢘꢗꢅꢘ (% ꢆꢉ
ꢂꢗꢊꢉꢜꢄꢛꢆ(ꢉ ꢞꢅꢘꢗꢅꢘ ꢝꢈꢊꢉ ꢅ%ꢊ$ ꢆ% ꢘꢈꢊ ꢀꢞꢅꢉꢘꢊꢛ.ꢎ(ꢙꢊꢛ ꢍꢊꢆ$& ꢂꢅꢘꢗꢅꢘꢒ
ꢂ,<
ꢂ,6
ꢂ,/
ꢂ,>
RXRDY/FFULL_A Output4 ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢍꢊꢆ$&. # ꢂ ꢅꢇꢇ #ꢉ$('ꢆꢘꢞꢛꢒ 7ꢞꢘꢊ4
ꢎꢈ(% (% ꢆꢉ ꢂꢗꢊꢉꢜꢄꢛꢆ(ꢉ ꢞꢅꢘꢗꢅꢘ +ꢞꢛ ꢘꢈꢊ ꢍ5ꢍꢄG. ꢋ99Fꢌ +ꢅꢉ'ꢘ(ꢞꢉꢒ
RXRDY/FFULL_B Output4 ꢀꢈꢆꢉꢉꢊꢇ * ꢍꢊ'ꢊ(ꢑꢊꢛ ꢍꢊꢆ$&. # ꢂ ꢅꢇꢇ #ꢉ$('ꢆꢘꢞꢛꢒ 7ꢞꢘꢊ4
ꢎꢈ(% (% ꢆꢉ ꢂꢗꢊꢉꢜꢄꢛꢆ(ꢉ ꢞꢅꢘꢗꢅꢘ +ꢞꢛ ꢘꢈꢊ ꢍ5ꢍꢄG. ꢋ99F* +ꢅꢉ'ꢘ(ꢞꢉꢒ
TXRDY_A Output4 ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢍꢊꢆ$& #ꢉ$('ꢆꢘꢞꢛꢒ ꢎꢈ(% (% ꢆꢉ ꢂꢗꢊꢉꢜꢄꢛꢆ(ꢉ
ꢞꢅꢘꢗꢅꢘ +ꢞꢛ ꢘꢈꢊ ꢎ5ꢍꢄGFꢌ +ꢅꢉ'ꢘ(ꢞꢉꢒ
TXRDY_B Output4 ꢀꢈꢆꢉꢉꢊꢇ * ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢍꢊꢆ$& #ꢉ$('ꢆꢘꢞꢛꢒ ꢎꢈ(% (% ꢆꢉ ꢂꢗꢊꢉꢜꢄꢛꢆ(ꢉ
ꢞꢅꢘꢗꢅꢘ +ꢞꢛ ꢘꢈꢊ ꢎ5ꢍꢄGF* +ꢅꢉ'ꢘ(ꢞꢉꢒ
Table 24. Listing of the Alternate Functions for the Output Port
ꢁꢆꢉ& ꢞ+ ꢘꢈꢊ ꢌꢇꢘꢊꢛꢉꢆꢘꢊ ꢅꢉ'ꢘ(ꢞꢉ% ꢞ+ ꢘꢈꢊ ꢑꢆꢛ(ꢞꢅ% ꢂꢅꢘꢗꢅꢘ ,ꢞꢛꢘ ꢗ(ꢉ% ꢆꢛꢊ %ꢊꢇꢊ'ꢘꢊ$ ꢚ& ꢝꢛ(ꢘ(ꢉ- ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ $ꢆꢘꢆ ꢘꢞ ꢘꢈꢊ ꢂ,ꢀꢍꢒ
ꢎꢈꢊ ꢚ(ꢘ +ꢞꢛꢙꢆꢘ ꢞ+ ꢘꢈ(% ꢛꢊ-(%ꢘꢊꢛ +ꢞꢇꢇꢞꢝ%
Bit 7
OP7
Bit 6
OP6
Bit 5
OP5
Bit 4
OP4
Bit 3
Bit 2
Bit 1
Bit 0
OP3
OP2
ꢕ J ꢂ,ꢍN>O ꢕ J ꢂ,ꢍN/O
ꢔ J ꢎ5ꢍꢄG* ꢔ J ꢎ5ꢍꢄGꢌ
ꢕ J ꢂ,ꢍN6O
ꢔ J ꢍ5ꢍꢄG.
ꢋ99*
ꢕ J ꢂ,ꢍN<O
ꢔ J ꢍ5ꢍꢄG.
ꢋ99ꢌ
ꢕꢕ J ꢂ,ꢍN1O
ꢕꢔ J ꢀ.ꢎ Sꢔ ꢂꢅꢘꢗꢅꢘ
ꢔꢕ J ꢎ5ꢀ* ꢏꢔ5ꢐ
ꢔꢔ J ꢍ5ꢀ* ꢏꢔ5ꢐ
ꢕꢕ J ꢂ,ꢍNꢓO
ꢕꢔ J ꢎ5ꢀꢌ ꢏꢔ/5ꢐ
ꢔꢕ J ꢎ5ꢀꢌ ꢏꢔ5ꢐ
ꢔꢔ J ꢍ5ꢀꢌ ꢏꢔ5ꢐ
Note: OPCR only addresses the alternate functions for Output Port pins, OP7 - OP2. OP0 and OP1 assume their RTS roles if either
MR1n[7] = 1 or MR2n[5] = 1. Setting those Mode Register bits enables the RTS function. Otherwise, these two ports will only
be General Purpose Output Ports.
Table 25. Output Port Configuration Register - OPCR
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
//
XR88C681
F.3 28 Pin DIP Packaged DUARTs
ꢎꢈ(% %ꢊ'ꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ $ꢆꢘꢆ %ꢈꢊꢊꢘ $(%'ꢅ%%ꢊ% ꢘꢈꢊ ꢛꢊ%ꢞꢅꢛ'ꢊ%
ꢘꢈꢆꢘ ꢆꢛꢊ ꢆꢑꢆ(ꢇꢆꢚꢇꢊ ꢘꢞ ꢊꢆ'ꢈ 'ꢈꢆꢉꢉꢊꢇꢒ ꢎꢈꢊ%ꢊ ꢛꢊ%ꢞꢅꢛ'ꢊ% ꢆꢛꢊ
ꢇ(%ꢘꢊ$ ꢈꢊꢛꢊ4
ꢎꢈꢊ ꢓ= ꢗ(ꢉ ꢄ#, ꢗꢆ'3ꢆ-ꢊ$ $ꢊꢑ('ꢊ% ꢈꢆꢑꢊ ꢞꢉꢇ& ꢘꢝꢞ ꢞꢅꢘꢗꢅꢘ
ꢗꢞꢛꢘ%" ꢂ,ꢕ ꢆꢉ$ ꢂ,ꢔꢒ 8ꢊꢉ'ꢊ ꢘꢈꢊ ꢊ++ꢊ'ꢘ ꢞ+ ꢘꢈꢊ Cꢃ2ꢎ
ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃD ꢆꢉ$ Cꢀ92ꢌꢍ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ
*#ꢎꢃD 'ꢞꢙꢙꢆꢉ$% ꢞꢉꢇ& ꢊ++ꢊ'ꢘ% ꢘꢈꢊ%ꢊ ꢘꢝꢞ ꢗ(ꢉ%ꢒ ꢌ$$(ꢘ(ꢞꢉꢆꢇꢇ&
ꢜꢍꢎꢃꢌ ꢆꢉ$ ꢜꢍꢎꢃ* ꢆꢛꢊ ꢘꢈꢊ ꢞꢉꢇ& ꢆꢇꢘꢊꢛꢉꢆꢘ(ꢑꢊ ꢞꢅꢘꢗꢅꢘ ꢗꢞꢛꢘ ꢗ(ꢉ
+ꢅꢉ'ꢘ(ꢞꢉ% ꢆꢑꢆ(ꢇꢆꢚꢇꢊ ꢘꢞ ꢘꢈ(% ꢑꢊꢛ%(ꢞꢉ ꢞ+ ꢘꢈꢊ 5ꢍ==ꢀ/=ꢔꢒ
ꢁ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢏꢎꢛꢆꢉ%ꢙ(ꢘ 8ꢞꢇ$(ꢉ- ꢍꢊ-(%ꢘꢊꢛ ꢆꢉ$ ꢎꢛꢆꢉ%ꢙ(ꢘ
ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛꢐ
ꢁ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢏꢍꢊ'ꢊ(ꢑꢊ 8ꢞꢇ$(ꢉ- ꢍꢊ-(%ꢘꢊꢛ ꢆꢉ$ ꢍꢊ'ꢊ(ꢑꢊ
ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛꢐ
ꢁ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ
ꢁ ꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛ%
G. SERIAL CHANNELS A and B
ꢁ ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ ꢏꢃꢊꢊ Section B.2" ꢀꢞꢙꢙꢆꢉ$
ꢄꢊ'ꢞ$(ꢉ-ꢐ
2ꢆ'ꢈ %ꢊꢛ(ꢆꢇ 'ꢈꢆꢉꢉꢊꢇ ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ 'ꢞꢙꢗꢛ(%ꢊ% ꢆ
+ꢅꢇꢇꢜ$ꢅꢗꢇꢊ! ꢆ%&ꢉ'ꢈꢛꢞꢉꢞꢅ% ꢛꢊ'ꢊ(ꢑꢊꢛ ꢆꢉ$ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛꢒ ꢎꢈꢊ
ꢘꢝꢞ 'ꢈꢆꢉꢉꢊꢇ% 'ꢆꢉ (ꢉ$ꢊꢗꢊꢉ$ꢊꢉꢘꢇ& %ꢊꢇꢊ'ꢘ ꢘꢈꢊ(ꢛ ꢞꢗꢊꢛꢆꢘ(ꢉ-
+ꢛꢊEꢅꢊꢉ'& ꢏ+ꢛꢞꢙ ꢘꢈꢊ *ꢍ0" ꢘꢈꢊ ꢀ.ꢎ" ꢞꢛ ꢆꢉ ꢊ!ꢘꢊꢛꢉꢆꢇ 'ꢇꢞ'3ꢐ ꢆ%
ꢝꢊꢇꢇ ꢆ% ꢞꢗꢊꢛꢆꢘ(ꢉ- ꢙꢞ$ꢊꢒ *ꢊ%($ꢊ% ꢘꢈꢊ ꢉꢞꢛꢙꢆꢇ ꢙꢞ$ꢊ (ꢉ
ꢝꢈ('ꢈ ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢆꢉ$ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢞ+ ꢊꢆ'ꢈ 'ꢈꢆꢉꢉꢊꢇ
ꢞꢗꢊꢛꢆꢘꢊ (ꢉ$ꢊꢗꢊꢉ$ꢊꢉꢘꢇ&" ꢘꢈꢊ ꢄꢋꢌꢍꢎ 'ꢆꢉ ꢚꢊ 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ
ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢑꢆꢛ(ꢞꢅ% ꢇꢞꢞꢗ(ꢉ- ꢙꢞ$ꢊ%" ꢝꢈ('ꢈ ꢆꢛꢊ ꢅ%ꢊ+ꢅꢇ +ꢞꢛ
ꢇꢞ'ꢆꢇ ꢆꢉ$ ꢛꢊꢙꢞꢘꢊ $(ꢆ-ꢉꢞ%ꢘ('%" ꢆ% ꢝꢊꢇꢇ ꢆ% (ꢉ ꢆ ꢝꢆ3ꢊ ꢅꢗ
ꢙꢞ$ꢊ ꢅ%ꢊ$ +ꢞꢛ ꢙꢅꢇꢘ(ꢜ$ꢛꢞꢗ ꢆꢗꢗꢇ('ꢆꢘ(ꢞꢉ%ꢒ
ꢁ ꢀꢇꢞ'3 ꢃꢊꢇꢊ'ꢘ ꢍꢊ-(%ꢘꢊꢛ ꢏꢃꢊꢊ Section D" ꢎ(ꢙ(ꢉ-
ꢀꢞꢉꢘꢛꢞꢇ *ꢇꢞ'3ꢐ
G.1 Transmitter (TSR and THR)
ꢎꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢆ''ꢊꢗꢘ% ꢗꢆꢛꢆꢇꢇꢊꢇ $ꢆꢘꢆ +ꢛꢞꢙ ꢘꢈꢊ ꢀ,ꢋ ꢆꢉ$
'ꢞꢉꢑꢊꢛꢘ% (ꢘ ꢘꢞ ꢆ %ꢊꢛ(ꢆꢇ ꢚ(ꢘ %ꢘꢛꢊꢆꢙ ꢝꢈꢊꢛꢊ (ꢘ (% ꢞꢅꢘꢗꢅꢘ ꢆꢘ ꢘꢈꢊ
ꢎ5ꢄꢉ ꢗ(ꢉ" ꢆ$$(ꢉ- %ꢘꢆꢛꢘ" %ꢘꢞꢗ ꢆꢉ$ ꢞꢗꢘ(ꢞꢉꢆꢇ ꢗꢆꢛ(ꢘ& ꢚ(ꢘ% ꢆ%
ꢛꢊEꢅ(ꢛꢊ$ ꢚ& ꢘꢈꢊ ꢆ%&ꢉ'ꢈꢛꢞꢉꢞꢅ% ꢗꢛꢞꢘꢞ'ꢞꢇꢒ
2ꢆ'ꢈ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ 'ꢞꢉ%(%ꢘ% ꢞ+ ꢆ ꢎꢛꢆꢉ%ꢙ(ꢘ ꢃꢈ(+ꢘ ꢛꢊ-(%ꢘꢊꢛ ꢏꢎꢃꢍꢐ
ꢆꢉ$ ꢆ ꢎꢛꢆꢉ%ꢙ(ꢘ 8ꢞꢇ$(ꢉ- ꢍꢊ-(%ꢘꢊꢛ ꢏꢎ8ꢍꢐꢒ ꢎꢈꢊ ꢎ8ꢍ (%
ꢆ'ꢘꢅꢆꢇꢇ& ꢆ ꢔ ꢚ&ꢘꢊ # ꢂꢒ Figure 35 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ %(ꢙꢗꢇ(+(ꢊ$
(ꢇꢇꢅ%ꢘꢛꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢎꢃꢍ ꢆꢉ$ ꢎ8ꢍꢒ ꢎꢈꢊ ꢀ,ꢋ (ꢉ(ꢘ(ꢆꢘꢊ% ꢘꢈꢊ
ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉ ꢞ+ %ꢊꢛ(ꢆꢇ $ꢆꢘꢆ ꢚ& ꢝꢛ(ꢘ(ꢉ- 'ꢈꢆꢛꢆ'ꢘꢊꢛ $ꢆꢘꢆ ꢘꢞ ꢘꢈꢊ
ꢎ8ꢍꢒ ꢎꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢝ(ꢇꢇ ꢚꢊ ꢇꢞꢆ$ꢊ$ (ꢉꢘꢞ ꢆꢉ$ ꢗꢛꢞ'ꢊ%%ꢊ$
ꢘꢈꢛꢞꢅ-ꢈ ꢘꢈꢊ # ꢂ" ꢅꢉꢘ(ꢇ (ꢘ ꢛꢊꢆ'ꢈꢊ% ꢘꢈꢊ ꢎꢃꢍꢒ ꢄꢅꢛ(ꢉ- ꢘꢈꢊ
ꢘꢛꢆꢉ%(ꢘ(ꢞꢉ +ꢛꢞꢙ ꢘꢈꢊ ꢎ8ꢍ ꢘꢞ ꢘꢈꢊ ꢎꢃꢍ" ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ $ꢆꢘꢆ (%
%ꢊꢛ(ꢆꢇ(Iꢊ$ ꢆꢉ$ (% ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ ꢞꢅꢘ ꢞ+ ꢘꢈꢊ 'ꢈ(ꢗ ꢑ(ꢆ ꢘꢈꢊ ꢎ5ꢄꢉ ꢗ(ꢉꢒ
#ꢉ ꢘꢈ(% %ꢊ'ꢘ(ꢞꢉ 'ꢊꢛꢘꢆ(ꢉ %&ꢙꢚꢞꢇ% ꢝ(ꢇꢇ ꢚꢊ ꢅ%ꢊ$ ꢘꢞ $ꢊꢉꢞꢘꢊ
'ꢊꢛꢘꢆ(ꢉ ꢆ%ꢗꢊ'ꢘ% ꢞ+ ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢆꢉ$ ꢍꢊ'ꢊ(ꢑꢊꢛꢒ ꢎꢈꢊ
$ꢊ+(ꢉ(ꢘ(ꢞꢉ ꢞ+ %ꢞꢙꢊ ꢞ+ ꢘꢈꢊ%ꢊ %&ꢙꢚꢞꢇ% +ꢞꢇꢇꢞꢝ%ꢒ
ꢎ5ꢄꢉ ꢜ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢏꢃꢊꢛ(ꢆꢇꢐ ꢄꢆꢘꢆ ꢂꢅꢘꢗꢅꢘ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ ꢉ
ꢎ5ꢀꢉ ꢜ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢀꢇꢞ'3 ꢃ(-ꢉꢆꢇ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ ꢉ
ꢍ5ꢄꢉ ꢜ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢏꢃꢊꢛ(ꢆꢇꢐ ꢄꢆꢘꢆ #ꢉꢗꢅꢘ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ ꢉ
ꢍ5ꢀꢉ ꢜ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢀꢇꢞ'3 ꢃ(-ꢉꢆꢇ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ ꢉ
ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢀꢇꢞ'3 ꢏ+ꢛꢞꢙ ꢎ(ꢙ(ꢉ- *ꢇꢞ'3ꢐ
ꢎ5ꢀꢉ
ꢎꢛꢆꢉ%ꢙ(ꢘ ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛ
ꢎ5ꢄꢉ
ꢂꢅꢘ-ꢞ(ꢉ-
ꢃꢊꢛ(ꢆꢇ ꢄꢆꢘꢆ
ꢛꢞꢙ ꢄꢆꢘꢆ *ꢅ%ꢒ
,ꢆꢛꢆꢇꢇꢊꢇ ꢄꢆꢘꢆ +ꢛꢞꢙ
ꢘꢈꢊ ꢀ,ꢋ
ꢎꢛꢆꢉ%ꢙ(ꢘ 8ꢞꢇ$(ꢉ-
ꢍꢊ-(%ꢘꢊꢛ
Figure 35. A Simplified Drawing Depicting the Transmit Shift Register and the Transmit Holding Register.
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
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XR88C681
Bꢈꢊꢉꢊꢑꢊꢛ ꢆ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% ($ꢇꢊ ꢞꢛ (ꢉꢆ'ꢘ(ꢑꢊ" ꢘꢈꢊ ꢎ5ꢄꢉ
ꢞꢅꢘꢗꢅꢘ +ꢞꢛ ꢘꢈꢆꢘ ꢗꢆꢛꢘ('ꢅꢇꢆꢛ 'ꢈꢆꢉꢉꢊꢇ ꢝ(ꢇꢇ ꢚꢊ 'ꢞꢉꢘ(ꢉꢅꢞꢅ%ꢇ&
ꢙꢆꢛ3(ꢉ- ꢏꢆꢘ ꢆ ꢇꢞ-(' Cꢈ(-ꢈDꢐꢒ 8ꢞꢝꢊꢑꢊꢛ" Mꢅ%ꢘ ꢗꢛ(ꢞꢛ ꢘꢞ ꢘꢈꢊ
ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉ ꢞ+ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ" ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢆꢇꢊꢛꢘ% ꢘꢈꢊ
ꢛꢊ'ꢊ(ꢑꢊꢛ ꢚ& -ꢊꢉꢊꢛꢆꢘ(ꢉ- ꢆ CꢃꢎꢌꢍꢎD ꢚ(ꢘꢒ ꢎꢈꢊ ꢃꢎꢌꢍꢎ ꢚ(ꢘ (%
ꢚꢆ%('ꢆꢇꢇ& ꢘꢈꢊ ꢎ5ꢄꢉ ꢞꢅꢘꢗꢅꢘ ꢘꢞ--ꢇ(ꢉ- CꢇꢞꢝD +ꢞꢛ ꢞꢉꢊ ꢚ(ꢘ ꢗꢊꢛ(ꢞ$"
+ꢞꢇꢇꢞꢝ(ꢉ- ꢆꢉ ($ꢇꢊ ꢗꢊꢛ(ꢞ$ ꢞꢛ ꢘꢈꢊ ꢃꢎꢂ, ꢚ(ꢘ ꢞ+ ꢘꢈꢊ ꢗꢛꢊ'ꢊ$(ꢉ-
'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ #ꢙꢙꢊ$(ꢆꢘꢊꢇ& ꢆ+ꢘꢊꢛ ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢃꢎꢌꢍꢎ
ꢚ(ꢘ" ꢘꢈꢊ ꢇꢊꢆ%ꢘ %(-ꢉ(+('ꢆꢉꢘ ꢚ(ꢘ ꢞ+ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢝ(ꢇꢇ ꢚꢊ %ꢊꢉꢘ
+(ꢛ%ꢘ" +ꢞꢇꢇꢞꢝꢊ$ ꢚ& ꢗꢛꢞ-ꢛꢊ%%(ꢑꢊꢇ& ꢙꢞꢛꢊ %(-ꢉ(+('ꢆꢉꢘ ꢚ(ꢘ%ꢒ #+ ꢘꢈꢊ
'ꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉ ꢗꢛꢞꢘꢞ'ꢞꢇ 'ꢆꢇꢇ% +ꢞꢛ (ꢘ" ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢝ(ꢇꢇ
%ꢊꢉ$ ꢆ Cꢗꢆꢛ(ꢘ&D ꢚ(ꢘ ꢚꢊꢘꢝꢊꢊꢉ ꢘꢈꢊ ꢙꢞ%ꢘ %(-ꢉ(+('ꢆꢉꢘ ꢚ(ꢘ ꢞ+ ꢘꢈꢊ
'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢆꢉ$ ꢘꢈꢊ ꢃꢎꢂ, ꢚ(ꢘꢒ Figure 36 ꢗꢛꢊ%ꢊꢉꢘ% ꢘꢈꢊ
ꢝꢆꢑꢊ+ꢞꢛꢙ ꢏ+ꢞꢛꢙꢆꢘꢐ ꢞ+ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢏꢎ5ꢄꢉꢐ ꢞꢅꢘꢗꢅꢘꢒ #ꢉ
ꢘꢈ(% 'ꢆ%ꢊ" ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% %ꢊꢉ$ 6ꢄꢔ/" ꢝ(ꢘꢈ =ꢜ7ꢜꢔ
ꢗꢛꢞꢘꢞ'ꢞꢇ ꢏ= ꢚ(ꢘ% ꢗꢊꢛ 'ꢈꢆꢛꢆ'ꢘꢊꢛ" 7ꢞꢜꢗꢆꢛ(ꢘ&" ꢔꢜꢃꢘꢞꢗ *(ꢘꢐꢒ
ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ #$ꢇꢊ
ꢞꢛ ꢃꢘꢞꢗ *(ꢘ
ꢎ5ꢄꢉ
ꢔ
ꢕ
ꢔ
ꢔ
ꢔ
ꢕ
ꢔ
ꢕ
ꢃꢘꢆꢛꢘ *(ꢘ
ꢃꢘꢞꢗ *(ꢘ
Figure 36. The Output Waveform of the Transmitter While Sending
5D (8-N-1 Protocol).
16
ꢎꢈꢊ ꢄꢋꢌꢍꢎ 'ꢆꢉ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ -ꢊꢉꢊꢛꢆꢘꢊ ꢆꢉ #ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢍꢊEꢅꢊ%ꢘ ꢘꢞ ꢘꢈꢊ ꢀ,ꢋ ꢚ& %ꢊꢘꢘ(ꢉ- #ꢁꢍNꢕO ꢆꢉ$ #ꢁꢍN<O +ꢞꢛ
ꢀꢈꢆꢉꢉꢊꢇ% ꢌ" ꢆꢉ$ *" ꢛꢊ%ꢗꢊ'ꢘ(ꢑꢊꢇ&ꢒ #ꢉ ꢘꢈ(% 'ꢆ%ꢊ" ꢘꢈꢊ ꢄꢋꢌꢍꢎ
G.2 Receiver (RSR and RHR
ꢎꢈꢊ +ꢅꢉ'ꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ %ꢊꢛ(ꢆꢇ ꢛꢊ'ꢊ(ꢑꢊꢛ (% ꢘꢞ ꢛꢊ'ꢊ(ꢑꢊꢛ %ꢊꢛ(ꢆꢇ $ꢆꢘꢆ
ꢆꢘ ꢘꢈꢊ ꢍ5ꢄꢉ (ꢉꢗꢅꢘL 'ꢞꢉꢑꢊꢛꢘ (ꢘ ꢘꢞ ꢗꢆꢛꢆꢇꢇꢊꢇ $ꢆꢘꢆ" ꢝꢈꢊꢛꢊ (ꢘ 'ꢆꢉ
ꢚꢊ ꢛꢊꢆ$ ꢚ& ꢘꢈꢊ ꢀ,ꢋꢒ ꢎꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ (% ꢆꢇ%ꢞ ꢛꢊ%ꢗꢞꢉ%(ꢚꢇꢊ +ꢞꢛ
'ꢞꢙꢗꢅꢘ(ꢉ- ꢆꢉ$ 'ꢈꢊ'3(ꢉ- ꢗꢆꢛ(ꢘ&" (+ ꢗꢆꢛ(ꢘ& (% ꢚꢊ(ꢉ- ꢅ%ꢊ$ꢒ
ꢝꢞꢅꢇ$ -ꢊꢉꢊꢛꢆꢘꢊ ꢆꢉ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢍꢊEꢅꢊ%ꢘ ꢆꢉ&ꢘ(ꢙꢊ
ꢆ
ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢎ8ꢍ ꢆꢉ$ ꢎꢃꢍ ꢆꢛꢊ ꢊꢙꢗꢘ& ꢞ+ 'ꢈꢆꢛꢆ'ꢘꢊꢛ%ꢒ ꢎꢈꢊ
ꢀ,ꢋ 'ꢆꢉ %ꢊꢛꢑ('ꢊ ꢘꢈ(% (ꢉꢘꢊꢛꢛꢅꢗꢘ ꢛꢊEꢅꢊ%ꢘ ꢚ& ꢝꢛ(ꢘ(ꢉ- ꢆ
'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢘꢞ ꢘꢈꢊ ꢊꢙꢗꢘ& ꢎ8ꢍꢒ
ꢎꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ 'ꢞꢉ%(%ꢘ% ꢞ+ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊ ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛ ꢏꢍꢃꢍꢐ
ꢆꢉ$ ꢆ ꢍꢊ'ꢊ(ꢑꢊ 8ꢞꢇ$(ꢉ- ꢍꢊ-(%ꢘꢊꢛ ꢏꢍ8ꢍꢐꢒ ꢎꢈꢊ ꢍ8ꢍ (%" (ꢉ
ꢊ%%ꢊꢉ'ꢊ" ꢆ ꢘꢈꢛꢊꢊ ꢚ&ꢘꢊ # ꢂꢒ ꢎꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢛꢊ'ꢊ(ꢑꢊ% $ꢆꢘꢆ ꢆꢘ
ꢘꢈꢊ ꢍ5ꢄꢉ ꢗ(ꢉ" ꢝꢈꢊꢛꢊ (ꢘ (% ꢗꢛꢞ'ꢊ%%ꢊ$ ꢘꢈꢛꢞꢅ-ꢈ ꢘꢈꢊ ꢍꢃꢍꢒ
ꢌ+ꢘꢊꢛꢝꢆꢛ$%" ꢘꢈꢊ $ꢆꢘꢆ (% 'ꢞꢉꢑꢊꢛꢘꢊ$ ꢘꢞ ꢗꢆꢛꢆꢇꢇꢊꢇ +ꢞꢛꢙꢆꢘ" ꢆꢉ$ (%
ꢘꢛꢆꢉ%+ꢊꢛꢛꢊ$ ꢘꢞ ꢘꢈꢊ ꢍ8ꢍꢒ ꢎꢈ(% 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢘꢈꢊꢉ ꢗꢛꢞ'ꢊ%%ꢊ$
ꢘꢈꢛꢞꢅ-ꢈ ꢘꢈꢊ 1 ꢚ&ꢘꢊ% ꢞ+ # ꢂꢒ ꢂꢉ'ꢊ ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊ$ 'ꢈꢆꢛꢆ'ꢘꢊꢛ
ꢛꢊꢆ'ꢈꢊ% ꢘꢈꢊ ꢘꢞꢗ ꢞ+ ꢘꢈꢊ # ꢂ" (ꢘ 'ꢆꢉ ꢚꢊ Cꢗꢞꢗꢗꢊ$D ꢞꢛ ꢛꢊꢆ$ ꢚ&
ꢘꢈꢊ ꢀ,ꢋL ꢝꢈꢊꢉ (ꢘ ꢛꢊꢆ$% ꢘꢈꢊ ꢍ8ꢍꢒ Figure 37 $ꢊꢗ('ꢘ% ꢆ
%(ꢙꢗꢇ(+(ꢊ$ $ꢛꢆꢝ(ꢉ- ꢞ+ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛꢒ
ꢎꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ 'ꢆꢉ ꢚꢊ ꢊꢉꢆꢚꢇꢊ$ ꢞꢛ $(%ꢆꢚꢇꢊ$ ꢑ(ꢆ ꢘꢈꢊ
ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ ꢏ%ꢊꢊ Section B.2ꢐꢒ #+ ꢘꢈꢊ 'ꢞꢙꢙꢆꢉ$ (%
(%%ꢅꢊ$ ꢘꢞ $(%ꢆꢚꢇꢊ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ" ꢝꢈ(ꢇꢊ ꢘꢈꢊꢛꢊ ꢆꢛꢊ %ꢘ(ꢇꢇ
'ꢈꢆꢛꢆ'ꢘꢊꢛ% (ꢉ ꢘꢈꢊ ꢎ8ꢍ ꢆꢉ$ ꢎꢃꢍ" ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢝ(ꢇꢇ
'ꢞꢉꢘ(ꢉꢅꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘ(ꢉ- ꢆꢇꢇ ꢞ+ ꢘꢈꢊ ꢛꢊꢙꢆ(ꢉ(ꢉ- $ꢆꢘꢆ ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ
ꢎ8ꢍ ꢆꢉ$ ꢎꢃꢍ" ꢅꢉꢘ(ꢇ ꢘꢈꢊ& ꢆꢛꢊ 'ꢞꢙꢗꢇꢊꢘꢊꢇ& ꢊꢙꢗꢘ& ꢞ+
'ꢈꢆꢛꢆ'ꢘꢊꢛ%ꢒ 7ꢞ ꢉꢊꢝ 'ꢈꢆꢛꢆ'ꢘꢊꢛ% 'ꢆꢉ ꢚꢊ ꢝꢛ(ꢘꢘꢊꢉ ꢘꢞ ꢘꢈꢊ ꢎ8ꢍ
ꢞꢉ'ꢊ ꢘꢈꢊ ꢄ#ꢃꢌ*92 ꢎꢍꢌ7ꢃꢁ#ꢎꢎ2ꢍ 'ꢞꢙꢙꢆꢉ$ ꢈꢆ% ꢚꢊꢊꢉ
(%%ꢅꢊ$ꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
/=
XR88C681
ꢍꢊ'ꢊ(ꢑꢊꢛ ꢀꢇꢞ'3 ꢏ+ꢛꢞꢙ ꢎ(ꢙ(ꢉ- *ꢇꢞ'3ꢐ
ꢍ5ꢀꢉ
ꢍꢊ'ꢊ(ꢑꢊ ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛ
ꢍ5ꢄꢉ
#ꢉ'ꢞꢙ(ꢉ-
ꢃꢊꢛ(ꢆꢇ ꢄꢆꢘꢆ
ꢎꢞ ꢄꢆꢘꢆ *ꢅ%
ꢎꢞ ꢚꢊ ꢛꢊꢆ$ ꢚ& ꢘꢈꢊ ꢀ,ꢋ
ꢍꢊ'ꢊ(ꢑꢊ 8ꢞꢇ$(ꢉ-
ꢍꢊ-(%ꢘꢊꢛ
Figure 37. A Simplified Drawing of the Receiver Shift Register
and Receiver Holding Register
ꢎꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ +ꢅꢉ'ꢘ(ꢞꢉ% ꢚ& %ꢊꢉ%(ꢉ- ꢘꢈꢊ ꢑꢞꢇꢘꢆ-ꢊ ꢇꢊꢑꢊꢇ ꢆꢘ ꢘꢈꢊ
ꢍ5ꢄꢉ (ꢉꢗꢅꢘꢒ Bꢈꢊꢉ ꢘꢈꢊ +ꢆꢛꢜꢊꢉ$ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% ($ꢇꢊ" (ꢘ% ꢎ5ꢄꢉ
ꢞꢅꢘꢗꢅꢘ ꢏꢆꢉ$ 'ꢞꢉ%ꢊEꢅꢊꢉꢘꢇ&" ꢘꢈꢊ ꢍ5ꢄꢉ (ꢉꢗꢅꢘꢐ (%
'ꢞꢉꢘ(ꢉꢅꢞꢅ%ꢇ& Cꢙꢆꢛ3(ꢉ-Dꢒ ꢄꢅꢛ(ꢉ- ꢘꢈ(% ꢗꢊꢛ(ꢞ$ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ (%
(ꢉꢆ'ꢘ(ꢑꢊ ꢆꢉ$ (% ꢉꢞꢘ ꢛꢊ'ꢊ(ꢑ(ꢉ- ꢞꢛ ꢗꢛꢞ'ꢊ%%(ꢉ- ꢆꢉ& $ꢆꢘꢆꢒ
8ꢞꢝꢊꢑꢊꢛ" ꢝꢈꢊꢉ ꢘꢈꢊ +ꢆꢛꢜꢊꢉ$ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ %ꢊꢉ$% ꢘꢈꢊ ꢃꢎꢌꢍꢎ
ꢚ(ꢘ" ꢏꢝ(ꢘꢈ (ꢘ% ꢎ5ꢄꢉ ꢞꢅꢘꢗꢅꢘ ꢘꢞ--ꢇ(ꢉ- CꢇꢞꢝDꢐ" ꢆ ꢛꢊ'ꢊ(ꢑꢊꢛ 'ꢇꢞ'3"
ꢝꢈ('ꢈ (% ꢔ/ ꢘ(ꢙꢊ% ꢘꢈꢊ ꢚꢆꢅ$ ꢛꢆꢘꢊ ꢏꢝ(ꢘꢈ ꢘꢈꢊ ꢔ/! 'ꢇꢞ'3ꢐ" ꢝ(ꢇꢇ
%ꢘꢆꢛꢘ %ꢆꢙꢗꢇ(ꢉ- ꢘꢈ(% ꢃꢎꢌꢍꢎ ꢚ(ꢘꢒ #+ ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ $ꢊꢘꢊꢛꢙ(ꢉꢊ%
ꢘꢈꢆꢘ (ꢘ% ꢍ5ꢄꢉ (ꢉꢗꢅꢘ (% %ꢘ(ꢇꢇ CꢇꢞꢝD ꢆ+ꢘꢊꢛ (ꢘ% >ꢘꢈ %ꢆꢙꢗꢇꢊ" ꢘꢈꢊꢉ
ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢈꢆꢛ$ꢝꢆꢛꢊ 'ꢞꢉ%($ꢊꢛ% ꢘꢈ(% %(-ꢉꢆꢇ ꢘꢞ ꢚꢊ ꢆ ꢑꢆꢇ($
ꢃꢎꢌꢍꢎ ꢚ(ꢘꢒ #+ ꢘꢈꢊ ꢍ5ꢄꢉ (ꢉꢗꢅꢘ (% ꢉꢞꢘ CꢇꢞꢝD ꢆꢘ ꢘꢈꢊ >ꢘꢈ
%ꢆꢙꢗꢇꢊ" ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢝ(ꢇꢇ (-ꢉꢞꢛꢊ ꢘꢈ(% $ꢞꢝꢉꢝꢆꢛ$ ꢗꢅꢇ%ꢊ ꢆ%
Cꢉꢞ(%ꢊDꢒ ꢛꢞꢙ ꢘꢈ(% >ꢘꢈ %ꢆꢙꢗꢇꢊ ꢞꢉ" ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢝ(ꢇꢇ
%ꢆꢙꢗꢇꢊ ꢊꢆ'ꢈ %ꢅ''ꢊ%%(ꢑꢊ ꢚ(ꢘ ꢆꢘ ꢞꢉꢊ ꢚ(ꢘꢜꢗꢊꢛ(ꢞ$ (ꢉꢘꢊꢛꢑꢆꢇ%
ꢏꢔ.ꢚꢆꢅ$ ꢛꢆꢘꢊꢐ ꢝ(ꢘꢈ ꢘꢈꢊ ꢔ! 'ꢇꢞ'3ꢒ ꢎꢈꢊ ꢗꢅꢛꢗꢞ%ꢊ ꢞ+ ꢘꢈ(% ꢔ/!
ꢀꢇꢞ'3 (% ꢘꢈꢊꢉ ꢘꢝꢞꢜ+ꢞꢇ$ꢒ
ꢓꢒ ꢎꢞ ꢊ%ꢘꢆꢚꢇ(%ꢈ ꢘꢈꢊ ꢗꢈꢆ%ꢊ ꢛꢊꢇꢆꢘ(ꢞꢉ%ꢈ(ꢗ ꢚꢊꢘꢝꢊꢊꢉ ꢘꢈꢊ ꢔ! ꢚ(ꢘ
%ꢆꢙꢗꢇ(ꢉ- 'ꢇꢞ'3" ꢆꢉ$ ꢘꢈꢊ (ꢉ'ꢞꢙ(ꢉ- %ꢊꢛ(ꢆꢇ $ꢆꢘꢆ %ꢘꢛꢊꢆꢙꢒ
ꢎꢈꢊ ($ꢊꢆ (% ꢘꢞ %ꢆꢙꢗꢇꢊ ꢊꢆ'ꢈ $ꢆꢘꢆ ꢚ(ꢘ (ꢉ ꢘꢈꢊ ꢙ($$ꢇꢊ ꢞ+ (ꢘ%
ꢚ(ꢘ ꢗꢊꢛ(ꢞ$ꢒ
Please note that if a 16X clock is selected for the receiver,
this over-sampling procedure occurs with each and every
start bit.
ꢎꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢝ(ꢇꢇ 'ꢞꢉꢘ(ꢉꢅꢊ ꢘꢞ %ꢆꢙꢗꢇꢊ ꢏꢆꢉ$ ꢛꢊ'ꢊ(ꢑꢊꢐ ꢊꢆ'ꢈ
ꢚ(ꢘ ꢞ+ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢘꢈꢆꢘ +ꢞꢇꢇꢞꢝ% ꢘꢈꢊ ꢃꢎꢌꢍꢎ ꢚ(ꢘ" ꢆꢘ ꢞꢉꢊꢜꢚ(ꢘ
ꢘ(ꢙꢊ (ꢉꢘꢊꢛꢑꢆꢇ%ꢒ ꢋꢗꢞꢉ ꢛꢊ'ꢊꢗꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛH% ꢁꢃ* ꢘꢈꢊ
ꢛꢊ'ꢊ(ꢑꢊꢛ ꢝ(ꢇꢇ 'ꢈꢊ'3 ꢗꢆꢛ(ꢘ& ꢏ(+ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ꢐ ꢞꢛ ꢝ(ꢇꢇ %ꢆꢙꢗꢇꢊ
+ꢞꢛ ꢘꢈꢊ ꢃꢎꢂ, ꢚ(ꢘꢒ #+ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ %ꢆꢙꢗꢇꢊ% ꢆ ꢙꢆꢛ3
'ꢞꢉ$(ꢘ(ꢞꢉ ꢆꢘ ꢘꢈ(% ꢘ(ꢙꢊ ꢆꢉ$ ꢘꢈꢊ ꢗꢆꢛ(ꢘ& 'ꢈꢊ'3 ꢏ(+ ꢆꢉ&ꢐ ꢝꢆ%
ꢑꢆꢇ($L ꢆ %ꢅ''ꢊ%%+ꢅꢇ ꢛꢊ'ꢊꢗꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (%
ꢗꢛꢊ%ꢅꢙꢊ$L ꢆꢉ$ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢝ(ꢇꢇ ꢗꢛꢊꢗꢆꢛꢊ ꢘꢞ %ꢊꢉ%ꢊ ꢆꢉ$
ꢞꢑꢊꢛ%ꢆꢙꢗꢇꢊ ꢘꢈꢊ ꢞ''ꢅꢛꢛꢊꢉ'ꢊ ꢞ+ ꢘꢈꢊ ꢃꢎꢌꢍꢎ ꢚ(ꢘ +ꢞꢛ ꢘꢈꢊ ꢉꢊ!ꢘ
'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ
ꢔꢒ ꢎꢞ ꢑꢊꢛ(+& ꢘꢈꢆꢘ ꢘꢈꢊ $ꢊꢘꢊ'ꢘꢊ$ CꢇꢞꢝD ꢇꢊꢑꢊꢇ (ꢉ ꢘꢈꢊ ꢍ5ꢄꢉ (ꢉꢗꢅꢘ
(% (ꢉ$ꢊꢊ$ ꢆ ꢃꢎꢌꢍꢎ ꢚ(ꢘꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
/ꢖ
XR88C681
Receiver Errors
ꢞꢉ'ꢊ ꢆ-ꢆ(ꢉ ꢚꢊ ꢛꢊEꢅꢊ%ꢘꢊ$ ꢏ(+ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ꢐ ꢆꢉ$ +ꢇꢆ--ꢊ$ (ꢉ
ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛꢒ
#+ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ $ꢞꢊ% ꢉꢞꢘ %ꢆꢙꢗꢇꢊ ꢆ Cꢙꢆꢛ3D" ꢆꢘ ꢘꢈꢊ ꢗꢛꢊ%ꢅꢙꢊ$
ꢘ(ꢙꢊ ꢞ+ ꢘꢈꢊ ꢃꢎꢂ, ꢚ(ꢘ" ꢆ ꢛꢆꢙ(ꢉ- 2ꢛꢛꢞꢛ ꢏ 2ꢐ (% +ꢇꢆ--ꢊ$ ꢚ&
%ꢊꢘꢘ(ꢉ-" ꢃꢍꢉN/O Jꢔꢒ #+" ꢅꢗꢞꢉ 'ꢞꢙꢗꢇꢊꢘꢊ ꢛꢊ'ꢊꢗꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ
'ꢈꢆꢛꢆ'ꢘꢊꢛ" ꢘꢈꢊ %ꢅꢚ%ꢊEꢅꢊꢉꢘ ꢗꢆꢛ(ꢘ& 'ꢈꢊ'3 (% (ꢉ'ꢞꢛꢛꢊ'ꢘ" ꢆ
,ꢆꢛ(ꢘ& 2ꢛꢛꢞꢛ ꢏ,2ꢐ (% +ꢇꢆ--ꢊ$ ꢚ& %ꢊꢘꢘ(ꢉ- ꢃꢍꢉN6O J ꢔꢒ #+ ꢘꢈꢊ
ꢍ8ꢍ ꢝꢆ% +ꢅꢇꢇ" ꢆꢉ$ ꢆꢉꢞꢘꢈꢊꢛ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢊ!(%ꢘꢊ$ (ꢉ ꢘꢈꢊ ꢍꢃꢍL
ꢆꢉ$ (+ ꢙꢞꢛꢊ $ꢆꢘꢆ ꢊꢉꢘꢊꢛ% ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢑ(ꢆ ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ-
ꢍ5ꢄꢉ ꢗ(ꢉL ꢘꢈꢊꢉ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (ꢉ ꢘꢈꢊ ꢍꢃꢍ ꢝ(ꢇꢇ ꢚꢊ
ꢞꢑꢊꢛꢝꢛ(ꢘꢘꢊꢉ" ꢆꢉ$ ꢆ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢂꢑꢊꢛꢛꢅꢉ 2ꢛꢛꢞꢛ ꢏꢂ2ꢐ 'ꢞꢉ$(ꢘ(ꢞꢉ
ꢝ(ꢇꢇ ꢚꢊ +ꢇꢆ--ꢊ$ (ꢉ ꢘꢈꢊ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ ꢏꢃꢍꢉN<O J ꢔꢐꢒ ꢎꢈ(%
ꢗꢈꢊꢉꢞꢙꢊꢉꢞꢉ ꢞꢚꢑ(ꢞꢅ%ꢇ& ꢛꢊ%ꢅꢇꢘ% (ꢉ ꢆ ꢇꢞ%% ꢞ+ $ꢆꢘꢆꢒ
ꢎꢈꢊ ꢄꢋꢌꢍꢎ 'ꢆꢉ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ -ꢊꢉꢊꢛꢆꢘꢊ ꢆꢉ #ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢍꢊEꢅꢊ%ꢘ ꢘꢞ ꢘꢈꢊ ꢀ,ꢋ (+ ꢆ ꢍ5ꢍꢄG ꢏꢍꢊ'ꢊ(ꢑꢊꢛ ꢍꢊꢆ$&ꢐ ꢞꢛ ꢆ
ꢋ99 ꢏ # ꢂ ꢅꢇꢇꢐ ꢀꢞꢉ$(ꢘ(ꢞꢉ ꢊ!(%ꢘ% +ꢞꢛ ꢊ(ꢘꢈꢊꢛ 'ꢈꢆꢉꢉꢊꢇꢒ ꢌ
ꢍ5ꢍꢄG ꢀꢞꢉ$(ꢘ(ꢞꢉ ꢊ!(%ꢘ% ꢝꢈꢊꢉ ꢆꢘ ꢇꢊꢆ%ꢘ ꢞꢉꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢞ+
$ꢆꢘꢆ ꢊ!(%ꢘ% ꢝ(ꢘꢈ(ꢉ ꢘꢈꢊ ꢍ8ꢍ" ꢆꢉ$ (% ꢅꢇꢘ(ꢙꢆꢘꢊꢇ& ꢝꢆ(ꢘ(ꢉ- ꢘꢞ ꢚꢊ
Cꢗꢞꢗꢗꢊ$D ꢆꢉ$ ꢛꢊꢆ$ ꢚ& ꢘꢈꢊ ꢀ,ꢋꢒ ꢎꢈꢊ ꢋ99 'ꢞꢉ$(ꢘ(ꢞꢉ
ꢊ!(%ꢘ% ꢝꢈꢊꢉ ꢘꢈꢊ ꢍ8ꢍ (% 'ꢞꢙꢗꢇꢊꢘꢊꢇ& +ꢅꢇꢇ ꢆꢉ$ 'ꢆꢉꢉꢞꢘ ꢆ''ꢊꢗꢘ
ꢆꢉ& ꢉꢊꢝ 'ꢈꢆꢛꢆ'ꢘꢊꢛ% +ꢛꢞꢙ ꢘꢈꢊ ꢍꢃꢍ ꢅꢉꢘ(ꢇ ꢘꢈꢊ ꢀ,ꢋ ꢈꢆ% ꢛꢊꢆ$
ꢞꢛ Cꢗꢞꢗꢗꢊ$D ꢘꢈꢊ # ꢂꢒ ꢎꢈꢊ ꢅ%ꢊꢛ 'ꢆꢉ %ꢊꢇꢊ'ꢘ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢍꢊEꢅꢊ%ꢘ ꢘꢞ ꢞ''ꢅꢛ $ꢅꢊ ꢘꢞ ꢊ(ꢘꢈꢊꢛ ꢏꢚꢅꢘ ꢉꢞꢘ ꢚꢞꢘꢈꢐ ꢘꢈꢊ ꢍ5ꢍꢄG
ꢞꢛ ꢋ99 'ꢞꢉ$(ꢘ(ꢞꢉ ꢑ(ꢆ ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇ ꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛ%ꢒ
ꢎꢈꢊ%ꢊ (ꢉꢘꢊꢛꢛꢅꢗꢘ% ꢆꢛꢊ ꢊꢉꢆꢚꢇꢊ$ ꢚ& %ꢊꢘꢘ(ꢉ- #ꢁꢍNꢔO ꢆꢉ$
#ꢁꢍN6O +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ% ꢌ ꢆꢉ$ *" ꢛꢊ%ꢗꢊ'ꢘ(ꢑꢊꢇ&ꢒ
(ꢉꢆꢇꢇ& (+ ꢘꢈꢊ ꢍ5ꢄꢉ (ꢉꢗꢅꢘ (% ꢈꢊꢇ$ ꢆꢘ ꢘꢈꢊ %ꢗꢆ'ꢊ 'ꢞꢉ$(ꢘ(ꢞꢉ +ꢞꢛ
ꢆꢉ ꢊꢉꢘ(ꢛꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢗꢊꢛ(ꢞ$" ꢆꢉ$ ꢉꢞ ꢃꢎꢂ, ꢚ(ꢘ ꢝꢆ% $ꢊꢘꢊ'ꢘꢊ$
ꢏꢃꢎꢂ, ꢚ(ꢘ %ꢆꢙꢗꢇ(ꢉ- ꢛꢊ%ꢅꢇꢘꢊ$ (ꢉ ꢆ %ꢗꢆ'ꢊꢐL ꢆ ꢍꢊ'ꢊ(ꢑꢊ$
*ꢛꢊꢆ3 ꢏꢍ*ꢐ 'ꢞꢉ$(ꢘ(ꢞꢉ (% ꢗꢛꢊ%ꢅꢙꢊ$ꢒ Bꢈꢊꢉ ꢘꢈ(% 'ꢞꢉ$(ꢘ(ꢞꢉ (%
$ꢊꢘꢊ'ꢘꢊ$ %ꢊꢑꢊꢛꢆꢇ ꢘꢈ(ꢉ-% ꢈꢆꢗꢗꢊꢉꢒ
2ꢆ'ꢈ 'ꢈꢆꢉꢉꢊꢇ (% ꢊEꢅ(ꢗꢗꢊ$ ꢝ(ꢘꢈ ꢉꢅꢙꢊꢛꢞꢅ% ꢞꢘꢈꢊꢛ ꢛꢊ-(%ꢘꢊꢛ%
ꢘꢈꢆꢘ ꢆꢛꢊ ꢅ%ꢊ$ ꢘꢞ ꢗꢛꢞꢑ($ꢊ 'ꢞꢉꢘꢛꢞꢇ ꢆꢉ$ ꢙꢞꢉ(ꢘꢞꢛ(ꢉ- ꢞ+ ꢘꢈꢊ%ꢊ
'ꢈꢆꢉꢉꢊꢇ%ꢒ ꢃꢞꢙꢊ ꢞ+ ꢘꢈꢊ%ꢊ ꢛꢊ-(%ꢘꢊꢛ% ꢝꢊꢛꢊ $(%'ꢅ%%ꢊ$ (ꢉ
ꢊꢆꢛꢇ(ꢊꢛ %ꢊ'ꢘ(ꢞꢉ% ꢞ+ ꢘꢈꢊ $ꢆꢘꢆ %ꢈꢊꢊꢘꢒ 8ꢞꢝꢊꢑꢊꢛ" ꢆ $ꢊꢘꢆ(ꢇꢊ$
$(%'ꢅ%%(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢛꢊꢙꢆ(ꢉ$ꢊꢛ ꢞ+ ꢘꢈꢊ%ꢊ ꢛꢊ-(%ꢘꢊꢛ% ꢆꢛꢊ
ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ Section G.3ꢒ
ꢔꢒ ꢎꢈꢊ Cꢍꢊ'ꢊ(ꢑꢊ$ *ꢛꢊꢆ3D 'ꢞꢉ$(ꢘ(ꢞꢉ (% +ꢇꢆ--ꢊ$ (ꢉ ꢘꢈꢊ
ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ ꢏꢃꢍꢉN>O J ꢔꢐꢒ
ꢓꢒ ꢎꢈꢊ C*ꢛꢊꢆ3D 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢇꢞꢆ$ꢊ$ (ꢉꢘꢞ ꢘꢈꢊ ꢍ8ꢍꢒ
8ꢞꢝꢊꢑꢊꢛ" ꢉꢞ +ꢅꢛꢘꢈꢊꢛ $ꢆꢘꢆ (% ꢛꢊ'ꢊ(ꢑꢊ$ ꢞꢛ ꢇꢞꢆ$ꢊ$ (ꢉꢘꢞ ꢘꢈꢊ
ꢍ8ꢍ ꢅꢉꢘ(ꢇ ꢘꢈꢊ ꢍ5ꢄꢉ (ꢉꢗꢅꢘ ꢛꢊꢘꢅꢛꢉ% ꢘꢞ ꢘꢈꢊ Cꢙꢆꢛ3D
'ꢞꢉ$(ꢘ(ꢞꢉꢒ
G.3 Mode Registers, MR1n and MR2n
1ꢒ ꢎꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- Cꢄꢊꢇꢘꢆ *ꢛꢊꢆ3D (ꢉꢘꢊꢛꢛꢅꢗꢘ (%
ꢛꢊEꢅꢊ%ꢘꢊ$ ꢏ(+ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ꢐ ꢆꢉ$ +ꢇꢆ--ꢊ$ (ꢉ ꢘꢈꢊ #ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢃꢘꢆꢘꢅ% ꢛꢊ-(%ꢘꢊꢛꢒ
ꢎꢈꢊ ꢁꢞ$ꢊ ꢍꢊ-(%ꢘꢊꢛ%" ꢆꢇꢇꢞꢝ ꢘꢈꢊ ꢅ%ꢊꢛ ꢘꢞ %ꢗꢊ'(+& ꢞ+ ꢘꢈꢊ
ꢗꢛꢞꢘꢞ'ꢞꢇ ꢗꢆꢛꢆꢙꢊꢘꢊꢛ% ꢘꢈꢆꢘ ꢈꢊ.%ꢈꢊ ꢝ(%ꢈ ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇ ꢘꢞ ꢛꢅꢉ
ꢆꢘꢒ ꢎꢈꢊ%ꢊ ꢛꢊ-(%ꢘꢊꢛ% ꢆꢇ%ꢞ ꢆꢇꢇꢞꢝ ꢘꢈꢊ ꢅ%ꢊꢛ ꢘꢞ 'ꢞꢉ+(-ꢅꢛꢊ ꢘꢈꢊ
ꢄꢋꢌꢍꢎ 'ꢈꢆꢉꢉꢊꢇ% ꢘꢞ ꢊꢉ-ꢆ-ꢊ (ꢉ ꢙꢞ$ꢊꢙ ꢈꢆꢉ$%ꢈꢆ3(ꢉ-
ꢘꢊ'ꢈꢉ(Eꢅꢊ%ꢒ ꢎꢈꢊ ꢚ(ꢘ% ꢞ+ ꢊꢆ'ꢈ ꢞ+ ꢘꢈꢊ%ꢊ ꢛꢊ-(%ꢘꢊꢛ% ꢆꢛꢊ
$(%'ꢅ%%ꢊ$ (ꢉ Table 26ꢒ
ꢂꢉ'ꢊ ꢘꢈꢊ ꢍ5ꢄꢉ (ꢉꢗꢅꢘ ꢛꢊꢘꢅꢛꢉ% ꢘꢞ ꢘꢈꢊ Cꢙꢆꢛ3D 'ꢞꢉ$(ꢘ(ꢞꢉ"
%ꢅꢚ%ꢊEꢅꢊꢉꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛ% ꢝ(ꢇꢇ ꢚꢊ ꢇꢞꢆ$ꢊ$ (ꢉꢘꢞ ꢘꢈꢊ ꢍ8ꢍ" ꢆꢉ$
ꢘꢈꢊ 'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- Cꢄꢊꢇꢘꢆ *ꢛꢊꢆ3D (ꢉꢘꢊꢛꢛꢅꢗꢘ 'ꢞꢉ$(ꢘ(ꢞꢉ ꢝ(ꢇꢇ
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Rx RTS
Control
Rx Interrupt Error Mode
Select
Parity Mode
Select
Parity
Select Number of Bits per
Character
Select
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕJꢍ!ꢍꢄG
ꢔJ ꢋ99
ꢕJꢀꢈꢆꢛꢆ'ꢘꢊꢛ
ꢔJ *ꢇꢞ'3
ꢕꢕ J B(ꢘꢈ ,ꢆꢛ(ꢘ&
ꢕꢔ J ꢞꢛ'ꢊ ,ꢆꢛ(ꢘ&
ꢔꢕ J 7ꢞ ,ꢆꢛ(ꢘ&
ꢕ J 2ꢑꢊꢉ
ꢔ J ꢂ$$
ꢕꢕ J 6
ꢕꢔ J /
ꢔꢕ J >
ꢔꢔ J =
ꢔꢔ J ꢁꢅꢇꢘ(ꢜꢄꢛꢞꢗ ꢁꢞ$ꢊ
Note: MR1n for each channel is accessed when the channel’s MR pointer points to MR1. The pointer is set to MR1n by a hardware
RESET or by a “RESET MR POINTER” command invoked via the channel’s command register. After any read or write to
MR1, the MR pointer will automatically point to MR2.
Table 26. Mode Registers - MR1A, MR1B
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
>ꢕ
XR88C681
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Channel Mode
Tx RTS
Control
CTS Enable
Tx
Bit Length
ꢕꢕ J 7ꢞꢛꢙꢆꢇ
ꢕꢔ J ꢌꢅꢘꢞ 2'ꢈꢞ
ꢔꢕ J 9ꢞ'ꢆꢇ 9ꢞꢞꢗ
ꢔꢔ J ꢍꢊꢙꢞꢘꢊ 9ꢞꢞꢗ
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J ꢕꢒ6/1
ꢔ J ꢕꢒ/ꢓ6
ꢓ J ꢕꢒ/==
1 J ꢕꢒ>6ꢕ
< J ꢕꢒ=ꢔ1
6 J ꢕꢒ=>6
/ J ꢕꢒꢖ1=
> J ꢔꢒꢕꢕꢕ
= J ꢔꢒ6/1
ꢖ J ꢔꢒ/ꢓ6
ꢌ J ꢔꢒ/==
* J ꢔꢒ>6ꢕ
ꢀ J ꢔꢒ=ꢔ1
ꢄ J ꢔꢒ=>6
2 J ꢔꢒꢖ1=
J ꢓꢒꢕꢕꢕ
Table 27. Mode Registers - MR2A, MR2B
MR1n[7] - Receiver Request to Send Control
ꢂꢍ ꢞ+ ꢘꢈꢊ %ꢘꢆꢘꢅ% +ꢞꢛ ꢆꢇꢇ 'ꢈꢆꢛꢆ'ꢘꢊꢛ% 'ꢞꢙ(ꢉ- ꢘꢞ ꢘꢈꢊ ꢘꢞꢗ ꢞ+ ꢘꢈꢊ
# ꢂ %(ꢉ'ꢊ ꢘꢈꢊ ꢇꢆ%ꢘ Cꢍ2ꢃ2ꢎ 2ꢍꢍꢂꢍ ꢃꢎꢌꢎꢋꢃD 'ꢞꢙꢙꢆꢉ$
+ꢞꢛ ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇ ꢝꢆ% (%%ꢅꢊ$ꢒ
ꢂꢛ$(ꢉꢆꢛ(ꢇ&" ꢍꢎꢃ ꢏꢍꢊEꢅꢊ%ꢘ ꢘꢞ ꢃꢊꢉ$ꢐ (% ꢆ%%ꢊꢛꢘꢊ$ ꢞꢛ ꢉꢊ-ꢆꢘꢊ$
ꢚ& (ꢉꢑꢞ3(ꢉ- ꢘꢈꢊ Cꢃ2ꢎ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃ ꢀꢂꢁꢁꢌ7ꢄD
ꢞꢛ Cꢀ92ꢌꢍ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃ ꢀꢂꢁꢁꢌ7ꢄD (ꢉ ꢘꢈꢊ
ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ ꢙꢆꢉꢉꢊꢛꢒ 8ꢞꢝꢊꢑꢊꢛ" (+ ꢁꢍꢔꢉN>O J ꢔ (% %ꢊꢘ" ꢘꢈꢊꢉ
ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢝ(ꢇꢇ ꢈꢆꢑꢊ 'ꢞꢉꢘꢛꢞꢇ ꢞꢑꢊꢛ ꢘꢈꢊ ꢉꢊ-ꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ
ꢜꢍꢎꢃꢉ ꢞꢅꢘꢗꢅꢘꢒ ꢃꢗꢊ'(+('ꢆꢇꢇ&" %ꢊꢘꢘ(ꢉ- ꢘꢈ(% ꢚ(ꢘ ꢝ(ꢇꢇ ꢆꢇꢇꢞꢝ ꢘꢈꢊ
ꢍꢊ'ꢊ(ꢑꢊꢛ ꢘꢞ ꢉꢊ-ꢆꢘꢊ ꢜꢍꢎꢃꢉ (+ (ꢘ% ꢍ8ꢍ (% +ꢅꢇꢇꢒ ꢎꢈ(% C+ꢇꢞꢝ
'ꢞꢉꢘꢛꢞꢇD ꢘꢊ'ꢈꢉ(Eꢅꢊ (% ꢅ%ꢊ+ꢅꢇ (ꢉ ꢗꢛꢊꢑꢊꢉꢘ(ꢉ- ꢍꢊ'ꢊ(ꢑꢊꢛ
ꢂꢑꢊꢛꢛꢅꢉ 2ꢛꢛꢞꢛ%ꢒ
MR1n[4:3] - Parity Mode Select
#+ Cꢝ(ꢘꢈ ꢗꢆꢛ(ꢘ&D ꢞꢛ C+ꢞꢛ'ꢊ ꢗꢆꢛ(ꢘ&D ꢞꢗꢊꢛꢆꢘ(ꢞꢉ (% ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$" ꢆ
ꢗꢆꢛ(ꢘ& ꢚ(ꢘ (% ꢆ$$ꢊ$ ꢘꢞ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ 'ꢈꢆꢛꢆ'ꢘꢊꢛ% ꢆꢉ$ ꢘꢈꢊ
ꢛꢊ'ꢊ(ꢑꢊꢛ ꢗꢊꢛ+ꢞꢛꢙ% ꢆ ꢗꢆꢛ(ꢘ& 'ꢈꢊ'3 ꢞꢉ ꢛꢊ'ꢊ(ꢑꢊ$ 'ꢈꢆꢛꢆ'ꢘꢊꢛ%ꢒ
ꢃꢊꢊ Section H.2 +ꢞꢛ $ꢊ%'ꢛ(ꢗꢘ(ꢞꢉ ꢞ+ ꢁꢅꢇꢘ(ꢜꢄꢛꢞꢗ ꢁꢞ$ꢊ
ꢂꢗꢊꢛꢆꢘ(ꢞꢉꢒ
Figure 42 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ $(ꢆ-ꢛꢆꢙ ꢝꢈ('ꢈ (ꢇꢇꢅ%ꢘꢛꢆꢘꢊ% ꢈꢞꢝ ꢆ
ꢍꢊ'ꢊ(ꢑꢊꢛꢜꢀꢞꢉꢘꢛꢞꢇꢇꢊ$ ꢍꢊEꢅꢊ%ꢘꢜꢘꢞꢜꢃꢊꢉ$ 'ꢞꢉ+(-ꢅꢛꢆꢘ(ꢞꢉ
ꢝꢞꢅꢇ$ +ꢅꢉ'ꢘ(ꢞꢉꢒ
MR1n[2] - Parity Type Select
ꢎꢈ(% ꢚ(ꢘ %ꢊꢇꢊ'ꢘ% ꢂꢄꢄ ꢞꢛ 2;27 ꢗꢆꢛ(ꢘ& (+ CB#ꢎ8 ,ꢌꢍ#ꢎG
ꢁꢂꢄ2D (% ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢆꢉ$ ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ +ꢞꢛ'ꢊ$ ꢗꢆꢛ(ꢘ&
ꢚ(ꢘ (+ ꢘꢈꢊ C ꢂꢍꢀ2 ,ꢌꢍ#ꢎGD ꢙꢞ$ꢊ (% ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ꢒ #ꢉ ꢘꢈꢊ
ꢁꢅꢇꢘ(ꢜꢄꢛꢞꢗ ꢙꢞ$ꢊ (ꢘ %ꢊꢇꢊ'ꢘ% ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ ꢘꢈꢊ ꢌ.ꢄ +ꢇꢆ- ꢚ(ꢘꢒ
ꢎꢈ(% ꢚ(ꢘ ꢈꢆ% ꢉꢞ ꢊ++ꢊ'ꢘ (+ C7ꢂ ,ꢌꢍ#ꢎGD (% %ꢊꢇꢊ'ꢘꢊ$ (ꢉ
ꢁꢍꢔꢉN<41Oꢒ
MR1n[6] - Receiver Interrupt Select
ꢎꢈ(% ꢚ(ꢘ %ꢊꢇꢊ'ꢘ% ꢊ(ꢘꢈꢊꢛ ꢘꢈꢊ ꢍ5ꢍꢄG %ꢘꢆꢘꢅ% ꢚ(ꢘ ꢞꢛ ꢘꢈꢊ ꢋ99
%ꢘꢆꢘꢅ% ꢚ(ꢘ ꢞ+ ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇ ꢘꢞ ꢚꢊ ꢅ%ꢊ$ ꢆ% ꢘꢈꢊ 'ꢛ(ꢘꢊꢛ(ꢆ +ꢞꢛ
-ꢊꢉꢊꢛꢆꢘ(ꢉ- ꢆꢉ #ꢉꢘꢊꢛꢛꢅꢗꢘ ꢍꢊEꢅꢊ%ꢘ ꢘꢞ ꢘꢈꢊ ꢀ,ꢋ" #ꢃꢍNꢔO +ꢞꢛ
ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢆꢉ$ #ꢃꢍN6O +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ *ꢒ
MR1n[1:0] - Bits per Character Select
ꢃꢊꢇꢊ'ꢘ% ꢘꢈꢊ ꢉꢅꢙꢚꢊꢛ ꢞ+ ꢚ(ꢘ% ꢘꢞ ꢚꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ ꢆꢉ$ ꢛꢊ'ꢊ(ꢑꢊ$
(ꢉ ꢘꢈꢊ $ꢆꢘꢆ +(ꢊꢇ$ ꢞ+ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ ꢎꢈ(% $ꢞꢊ% ꢉꢞꢘ (ꢉ'ꢇꢅ$ꢊ
ꢃꢎꢌꢍꢎ" ,ꢌꢍ#ꢎG" ꢆꢉ$ ꢃꢎꢂ, ꢚ(ꢘ%ꢒ
MR1n[5] - Error Mode Select
ꢎꢈ(% ꢚ(ꢘ 'ꢞꢉꢘꢛꢞꢇ% ꢘꢈꢊ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢘꢈꢛꢊꢊ # ꢂ %ꢘꢆꢘꢅ% ꢚ(ꢘ%
ꢏ,2" 2" ꢍꢊ'ꢊ(ꢑꢊ$ *ꢛꢊꢆ3ꢐ +ꢞꢛ ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇꢒ #+ ꢘꢈ(% ꢚ(ꢘ (% %ꢊꢘ
ꢘꢞ CꢕD" ꢘꢈ(% ꢗꢆꢛꢘ('ꢅꢇꢆꢛ 'ꢈꢆꢉꢉꢊꢇ ꢝ(ꢇꢇ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈꢊ
Cꢀꢈꢆꢛꢆ'ꢘꢊꢛD 2ꢛꢛꢞꢛ ꢁꢞ$ꢊꢒ #+ ꢘꢈ(% ꢚ(ꢘ% (% %ꢊꢘ ꢘꢞ CꢔD" ꢘꢈ(%
ꢗꢆꢛꢘ('ꢅꢇꢆꢛ 'ꢈꢆꢉꢉꢊꢇ ꢝ(ꢇꢇ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈꢊ C*ꢇꢞ'3D 2ꢛꢛꢞꢛ ꢁꢞ$ꢊꢒ
Mode Register 2 (Channels A and B)
ꢁꢍꢓꢉ +ꢞꢛ ꢊꢆ'ꢈ ꢀꢈꢆꢉꢉꢊꢇ (% ꢆ''ꢊ%%ꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇH%
ꢁꢍ ,ꢞ(ꢉꢘꢊꢛ ꢗꢞ(ꢉꢘ% ꢘꢞ ꢁꢍꢓꢉ" ꢝꢈ('ꢈ ꢞ''ꢅꢛ% ꢆ+ꢘꢊꢛ ꢆꢉ&
ꢆ''ꢊ%% ꢘꢞ ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇH% ꢁꢍꢔ ꢍꢊ-(%ꢘꢊꢛꢒ ꢃꢅꢚ%ꢊEꢅꢊꢉꢘ
Cꢛꢊꢆ$%D ꢞꢛ Cꢝꢛ(ꢘꢊ%D ꢘꢞ ꢁꢍꢓꢉ $ꢞꢊ% ꢉꢞꢘ 'ꢈꢆꢉ-ꢊ ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ%
ꢞ+ ꢘꢈꢊ ꢁꢍ ꢗꢞ(ꢉꢘꢊꢛꢒ
#ꢉ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢙꢞ$ꢊ ꢘꢈꢊ%ꢊ %ꢘꢆꢘꢅ% ꢚ(ꢘ% ꢆꢗꢗꢇ& ꢞꢉꢇ& ꢘꢞ ꢘꢈꢊ
'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢘꢈꢆꢘ (% 'ꢅꢛꢛꢊꢉꢘꢇ& ꢆꢘ ꢘꢈꢊ ꢘꢞꢗ ꢞ+ ꢘꢈꢊ # ꢂꢒ #ꢉ ꢘꢈꢊ
ꢚꢇꢞ'3 ꢙꢞ$ꢊ" ꢘꢈꢊ%ꢊ ꢚ(ꢘ% ꢛꢊꢗꢛꢊ%ꢊꢉꢘ ꢘꢈꢊ 'ꢅꢙꢅꢇꢆꢘ(ꢑꢊ ꢇꢞ-('ꢆꢇ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
>ꢔ
XR88C681
MR2n[7:6] - Channel Mode Select
ꢁ ꢃꢊꢘꢘ(ꢉ- ꢁꢍꢓꢉN>4/O J ꢕꢔ ꢗꢇꢆ'ꢊ% ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇ (ꢉ ꢘꢈꢊ ꢌꢅꢘꢞꢜ
ꢙꢆꢘ(' 2'ꢈꢞ ꢁꢞ$ꢊ" ꢝꢈ('ꢈ ꢆꢅꢘꢞꢙꢆꢘ('ꢆꢇꢇ& ꢛꢊꢜꢘꢛꢆꢉ%ꢙ(ꢘ%
ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊ$ $ꢆꢘꢆꢒ Figure 39 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ $(ꢆ-ꢛꢆꢙ $ꢊꢜ
ꢗ('ꢘ(ꢉ- ꢌꢅꢘꢞꢙꢆꢘ(' 2'ꢈꢞ ꢁꢞ$ꢊ ꢂꢗꢊꢛꢆꢘ(ꢞꢉꢒ ꢎꢈꢊ +ꢞꢇꢇꢞꢝꢜ
(ꢉ- 'ꢞꢉ$(ꢘ(ꢞꢉ% ꢆꢗꢗꢇ& ꢝꢈ(ꢇꢊ (ꢉ ꢘꢈ(% ꢙꢞ$ꢊꢒ
2ꢆ'ꢈ ꢀꢈꢆꢉꢉꢊꢇ 'ꢆꢉ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢞꢉꢊ ꢞ+ +ꢞꢅꢛ ꢙꢞ$ꢊ%ꢒ
ꢁ ꢃꢊꢘꢘ(ꢉ- ꢁꢍꢓꢉN>4/O J ꢕꢕ 'ꢞꢉ+(-ꢅꢛꢊ% ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇ ꢘꢞ ꢞꢗꢜ
ꢊꢛꢆꢘꢊ (ꢉ ꢘꢈꢊ 7ꢞꢛꢙꢆꢇ ꢁꢞ$ꢊꢒ #ꢉ ꢘꢈ(% ꢙꢞ$ꢊ" ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ
ꢆꢉ$ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ$ꢊꢗꢊꢉ$ꢊꢉꢘꢇ&ꢒ Figure 38
ꢗꢛꢊ%ꢊꢉꢘ% ꢆ $(ꢆ-ꢛꢆꢙ $ꢊꢗ('ꢘ(ꢉ- 7ꢞꢛꢙꢆꢇ ꢁꢞ$ꢊ ꢂꢗꢊꢛꢆꢜ
ꢘ(ꢞꢉꢒ
ꢍ5ꢀꢉ
ꢎ5ꢀꢉ
ꢍ5ꢄꢉ
ꢎ5ꢄꢉ
ꢂꢅꢘ-ꢞ(ꢉ- ꢃꢊꢛ(ꢆꢇ
ꢄꢆꢘꢆ
#ꢉ'ꢞꢙ(ꢉ-
ꢍꢊ'ꢊ(ꢑꢊ ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛ
ꢃꢊꢛ(ꢆꢇ ꢄꢆꢘꢆ
ꢎꢛꢆꢉ%ꢙ(ꢘ ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛ
ꢎꢛꢆꢉ%ꢙ(ꢘ 8ꢞꢇ$(ꢉ-
ꢍꢊ-(%ꢘꢊꢛ
ꢍꢊ'ꢊ(ꢑꢊ 8ꢞꢇ$(ꢉ-
ꢍꢊ-(%ꢘꢊꢛ
=
=
ꢛꢞꢙ ꢄꢆꢘꢆ *ꢅ%ꢒ
ꢏ,ꢆꢛꢆꢇꢇꢊꢇ $ꢆꢘꢆ +ꢛꢞꢙ ꢘꢈꢊ ꢀ,ꢋꢐ
ꢎꢞ ꢄꢆꢘꢆ *ꢅ%
ꢏꢎꢞ ꢚꢊ ꢛꢊꢆ$ ꢚ& ꢘꢈꢊ ꢀ,ꢋꢐ
Figure 38. A Block Diagram Depicting Normal Mode Operation.
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
>ꢓ
XR88C681
ꢍ5ꢀꢉ
ꢎ5ꢀꢉ
ꢍ5ꢄꢉ
ꢎ5ꢄꢉ ꢂꢅꢘ-ꢞ(ꢉ- ꢃꢊꢛ(ꢆꢇ
#ꢉ'ꢞꢙ(ꢉ-
ꢎꢛꢆꢉ%ꢙ(ꢘ ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛ
ꢍꢊ'ꢊ(ꢑꢊ ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛ
ꢄꢆꢘꢆ
ꢃꢊꢛ(ꢆꢇ ꢄꢆꢘꢆ
ꢎꢛꢆꢉ%ꢙ(ꢘ 8ꢞꢇ$(ꢉ-
ꢍꢊ-(%ꢘꢊꢛ
ꢍꢊ'ꢊ(ꢑꢊ 8ꢞꢇ$(ꢉ-
ꢍꢊ-(%ꢘꢊꢛ
=
ꢀ,ꢋ ꢈꢆ% ꢉꢞ ꢆ''ꢊ%% ꢘꢞ
ꢘꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ
ꢎꢞ ꢄꢆꢘꢆ *ꢅ%
ꢏꢎꢞ ꢚꢊ ꢛꢊꢆ$ ꢚ& ꢘꢈꢊ ꢀ,ꢋꢐ
Figure 39. A Block Diagram Depict Automatic Echo Mode
#ꢉ ꢘꢈ(% ꢙꢞ$ꢊ4
ꢔꢒ ꢍꢊ'ꢊ(ꢑꢊ$ $ꢆꢘꢆ (% ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ ꢞꢉ ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇH% ꢎ5ꢄ
ꢞꢅꢘꢗꢅꢘꢒ
/ꢒ ꢌ ꢛꢊ'ꢊ(ꢑꢊ$ ꢚꢛꢊꢆ3 (% ꢊ'ꢈꢞꢊ$ ꢆ% ꢛꢊ'ꢊ(ꢑꢊ$ ꢅꢉꢘ(ꢇ ꢘꢈꢊ ꢉꢊ!ꢘ
ꢑꢆꢇ($ %ꢘꢆꢛꢘ ꢚ(ꢘ (% $ꢊꢘꢊ'ꢘꢊ$ꢒ
>ꢒ ꢀ,ꢋ ꢘꢞ ꢛꢊ'ꢊ(ꢑꢊꢛ 'ꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉ% ꢞꢗꢊꢛꢆꢘꢊ% ꢉꢞꢛꢙꢆꢇꢇ&"
ꢚꢅꢘ ꢘꢈꢊ ꢀ,ꢋ ꢘꢞ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢇ(ꢉ3 (% $(%ꢆꢚꢇꢊ$ꢒ
ꢓꢒ ꢎꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢙꢅ%ꢘ ꢚꢊ ꢊꢉꢆꢚꢇꢊ$ ꢚꢅꢘ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢉꢊꢊ$
ꢉꢞꢘ ꢚꢊ ꢊꢉꢆꢚꢇꢊ$ꢒ
2ꢆ'ꢈ ꢄꢋꢌꢍꢎ 'ꢈꢆꢉꢉꢊꢇ 'ꢆꢉ ꢚꢊ 'ꢞꢉ+(-ꢅꢛꢊ$ (ꢉꢘꢞ ꢞꢉꢊ ꢞ+ ꢘꢝꢞ
$(ꢆ-ꢉꢞ%ꢘ(' ꢙꢞ$ꢊ%ꢒ
1ꢒ ꢎꢈꢊ 'ꢈꢆꢉꢉꢊꢇH% ꢎ5ꢍꢄG ꢆꢉ$ ꢎ52ꢁꢎ %ꢘꢆꢘꢅ% ꢚ(ꢘ% ꢆꢛꢊ
(ꢉꢆ'ꢘ(ꢑꢊꢒ
Local Loopback Mode
<ꢒ ꢎꢈꢊ ꢛꢊ'ꢊ(ꢑꢊ$ ꢗꢆꢛ(ꢘ& (% 'ꢈꢊ'3ꢊ$ ꢚꢅꢘ (% ꢉꢞꢘ -ꢊꢉꢊꢛꢆꢘꢊ$ +ꢞꢛ
ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉꢒ ꢎꢈꢅ%" ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ ꢗꢆꢛ(ꢘ& (% ꢆ% ꢛꢊ'ꢊ(ꢑꢊ$ꢒ
ꢎꢈ(% ꢙꢞ$ꢊ (% %ꢊꢇꢊ'ꢘꢊ$ ꢚ& %ꢊꢘꢘ(ꢉ- ꢁꢍꢓꢉN>4/O J ꢔꢕꢒ
Figure 40 (% ꢆ $(ꢆ-ꢛꢆꢙ $ꢊꢗ('ꢘ(ꢉ- 9ꢞ'ꢆꢇ 9ꢞꢞꢗꢚꢆ'3 ꢁꢞ$ꢊ
ꢞꢗꢊꢛꢆꢘ(ꢞꢉꢒ
6ꢒ ꢀꢈꢆꢛꢆ'ꢘꢊꢛ +ꢛꢆꢙ(ꢉ- (% 'ꢈꢊ'3ꢊ$ ꢚꢅꢘ ꢘꢈꢊ %ꢘꢞꢗ ꢚ(ꢘ% ꢆꢛꢊ
ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ ꢆ% ꢛꢊ'ꢊ(ꢑꢊ$ꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
>1
XR88C681
;
ꢀꢀ
ꢎ5ꢀꢉ
ꢍꢊ'ꢊ(ꢑꢊ ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛ
ꢎꢛꢆꢉ%ꢙ(ꢘ ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛ
ꢍ5ꢄꢉ
ꢎ5ꢄꢉ
ꢎꢛꢆꢉ%ꢙ(ꢘ 8ꢞꢇ$(ꢉ-
ꢍꢊ-(%ꢘꢊꢛ
ꢍꢊ'ꢊ(ꢑꢊ 8ꢞꢇ$(ꢉ-
ꢍꢊ-(%ꢘꢊꢛ
=
=
ꢎꢞ ꢄꢆꢘꢆ *ꢅ%
ꢏꢎꢞ ꢚꢊ ꢛꢊꢆ$ ꢚ& ꢘꢈꢊ ꢀ,ꢋꢐ
ꢛꢞꢙ ꢄꢆꢘꢆ *ꢅ%ꢒ
ꢏ,ꢆꢛꢆꢇꢇꢊꢇ ꢄꢆꢘꢆ +ꢛꢞꢙ ꢀ,ꢋꢐ
Figure 40. A Block Diagram depicting Local Loopback Mode Operation
#ꢉ ꢘꢈ(% ꢙꢞ$ꢊ4
ꢔꢒ ꢎꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢞꢅꢘꢗꢅꢘ (% (ꢉꢘꢊꢛꢉꢆꢇꢇ& 'ꢞꢉꢉꢊ'ꢘꢊ$ ꢘꢞ ꢘꢈꢊ
ꢛꢊ'ꢊ(ꢑꢊꢛ (ꢉꢗꢅꢘꢒ
Remote Loopback Mode.
ꢎꢈ(% ꢙꢞ$ꢊ (% %ꢊꢇꢊ'ꢘꢊ$ ꢚ& %ꢊꢘꢘ(ꢉ- ꢁꢍꢓꢉN>4/O J ꢔꢔꢒ
ꢓꢒ ꢎꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘ 'ꢇꢞ'3 (% ꢅ%ꢊ$ +ꢞꢛ ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛꢒ
1ꢒ ꢎꢈꢊ 'ꢈꢆꢉꢉꢊꢇH% ꢎ5ꢄꢉ ꢞꢅꢘꢗꢅꢘ (% ꢈꢊꢇ$ ꢙꢆꢛ3(ꢉ- ꢏꢈ(-ꢈꢐꢒ
<ꢒ ꢎꢈꢊ 'ꢈꢆꢉꢉꢊꢇH% ꢍ5ꢄꢉ (ꢉꢗꢅꢘ (% (-ꢉꢞꢛꢊ$ꢒ
Figure 41 ꢗꢛꢊ%ꢊꢉꢘ%
ꢆ $(ꢆ-ꢛꢆꢙ $ꢊꢗ('ꢘ(ꢉ- ꢍꢊꢙꢞꢘꢊ
9ꢞꢞꢗꢚꢆ'3 ꢁꢞ$ꢊ ꢞꢗꢊꢛꢆꢘ(ꢞꢉꢒ
6ꢒ ꢎꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% ꢊꢉꢆꢚꢇꢊ$" ꢚꢅꢘ ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊ$ ꢉꢊꢊ$ ꢉꢞꢘ
ꢚꢊ ꢊꢉꢆꢚꢇꢊ$ꢒ
/ꢒ ꢀ,ꢋ ꢘꢞ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢆꢉ$ ꢛꢊ'ꢊ(ꢑꢊꢛ 'ꢞꢙꢙꢅꢉ('ꢆꢘ(ꢞꢉ%
'ꢞꢉꢘ(ꢉꢅꢊ ꢉꢞꢛꢙꢆꢇꢇ&ꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
><
XR88C681
ꢍ5ꢀꢉ
ꢎ5ꢀꢉ
ꢎ5ꢄꢉ
ꢍ5ꢄꢉ
#ꢉ'ꢞꢙ(ꢉ-
ꢂꢅꢘ-ꢞ(ꢉ-
ꢍꢊ'ꢊ(ꢑꢊ ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛ
ꢎꢛꢆꢉ%ꢙ(ꢘ ꢃꢈ(+ꢘ ꢍꢊ-(%ꢘꢊꢛ
ꢃꢊꢛ(ꢆꢇ ꢄꢆꢘꢆ
ꢃꢊꢛ(ꢆꢇ ꢄꢆꢘꢆ
ꢎꢛꢆꢉ%ꢙ(ꢘ 8ꢞꢇ$(ꢉ-
ꢍꢊ-(%ꢘꢊꢛ
ꢍꢊ'ꢊ(ꢑꢊ 8ꢞꢇ$(ꢉ-
ꢍꢊ-(%ꢘꢊꢛ
Note: The CPU has no access to the Serial Data during Remote Loopback Mode.
Figure 41. A Block Diagram Depicting Remote Loopback Mode
#ꢉ ꢘꢈ(% ꢙꢞ$ꢊ4
ꢔꢒ ꢍꢊ'ꢊ(ꢑꢊ$ $ꢆꢘꢆ (% ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ ꢞꢉ ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇH% ꢎ5ꢄꢉ
ꢞꢅꢘꢗꢅꢘ
ꢘ(ꢙꢊ ꢆ+ꢘꢊꢛ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ% (ꢉ ꢘꢈꢊ ꢎꢃꢍ ꢆꢉ$ ꢎ8ꢍ ꢈꢆꢑꢊ ꢚꢊꢊꢉ
ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ ꢆꢉ$ ꢆꢛꢊ ꢉꢞꢝ ꢊꢙꢗꢘ&ꢒ
ꢓꢒ ꢍꢊ'ꢊ(ꢑꢊ$ $ꢆꢘꢆ (% ꢉꢞꢘ %ꢊꢉꢘ ꢘꢞ ꢘꢈꢊ ꢀ,ꢋ ꢆꢉ$ ꢘꢈꢊ ꢊꢛꢛꢞꢛ
%ꢘꢆꢘꢅ% 'ꢞꢉ$(ꢘ(ꢞꢉ% ꢆꢛꢊ ꢉꢞꢘ 'ꢈꢊ'3ꢊ$ꢒ
Figure 44 ꢗꢛꢊ%ꢊꢉꢘ%
ꢆ
$(ꢆ-ꢛꢆꢙ (ꢇꢇꢅ%ꢘꢛꢆꢘꢊ ꢈꢞꢝ
ꢆ
ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛꢜꢀꢞꢉꢘꢛꢞꢇꢇꢊ$ ꢍꢊEꢅꢊ%ꢘꢜꢘꢞꢜꢃꢊꢉ$ 'ꢞꢉ+(-ꢅꢛꢆꢘ(ꢞꢉ
ꢝꢞꢅꢇ$ +ꢅꢉ'ꢘ(ꢞꢉꢒ
1ꢒ ,ꢆꢛ(ꢘ& ꢆꢉ$ +ꢛꢆꢙ(ꢉ- ꢏ%ꢘꢞꢗ ꢚ(ꢘ%ꢐ ꢆꢛꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ ꢆ%
ꢛꢊ'ꢊ(ꢑꢊ$ꢒ
MR2n[4] - Clear to Send Control
<ꢒ ꢎꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢙꢅ%ꢘ ꢚꢊ ꢊꢉꢆꢚꢇꢊ$ꢒ
#+ ꢘꢈ(% ꢚ(ꢘ (% ꢆ ꢕ" ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇ% ꢜꢀꢎꢃꢉ (ꢉꢗꢅꢘ ꢏ#,ꢕ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ
ꢌ" ꢞꢛ #,ꢔ +ꢞꢛ ꢀꢈꢆꢉꢉꢊꢇ *ꢐ ꢈꢆ% ꢉꢞ ꢊ++ꢊ'ꢘ ꢞꢉ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛꢒ #+
ꢘꢈꢊ ꢚ(ꢘ (% ꢆ CꢔD" ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢝ(ꢇꢇ 'ꢈꢊ'3 ꢘꢈꢊ %ꢘꢆꢘꢊ ꢞ+ (ꢘ%
ꢜꢀꢎꢃꢉ (ꢉꢗꢅꢘ ꢊꢆ'ꢈ ꢘ(ꢙꢊ (% (ꢘ ꢛꢊꢆ$& ꢘꢞ %ꢊꢉ$ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ #+
ꢜꢀꢎꢃꢉ (% ꢇꢞꢝ ꢏꢞꢛ CꢘꢛꢅꢊDꢐ" ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ꢒ #+
ꢜꢀꢎꢃꢉ (% ꢈ(-ꢈ ꢏꢞꢛ ꢉꢊ-ꢆꢘꢊ$ꢐ" ꢎ5ꢄꢉ ꢛꢊꢙꢆ(ꢉ% (ꢉ ꢘꢈꢊ ꢙꢆꢛ3(ꢉ-
%ꢘꢆꢘꢊ ꢆꢉ$ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢉꢊ!ꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (%
$ꢊꢇꢆ&ꢊ$ ꢅꢉꢘ(ꢇ ꢜꢀꢎꢃꢉ -ꢞꢊ% ꢇꢞꢝꢒ ꢀꢈꢆꢉ-ꢊ% (ꢉ ꢘꢈꢊ ꢜꢀꢎꢃꢉ
(ꢉꢗꢅꢘ ꢝꢈ(ꢇꢊ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢚꢊ(ꢉ- %ꢊꢛ(ꢆꢇ(Iꢊ$ $ꢞ ꢉꢞꢘ ꢆ++ꢊ'ꢘ
ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉ ꢞ+ ꢘꢈꢆꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ ꢎꢈ(% ꢗꢈꢊꢉꢞꢙꢊꢉꢞꢉ (%
+ꢅꢛꢘꢈꢊꢛ (ꢇꢇꢅ%ꢘꢛꢆꢘꢊ$ (ꢉ Figure 42 ꢆꢉ$ Figure 44ꢒ
6ꢒ ꢎꢈꢊ ꢛꢊ'ꢊ(ꢑꢊ$ ꢚꢛꢊꢆ3 (% ꢊ'ꢈꢞꢊ$ ꢆ% ꢛꢊ'ꢊ(ꢑꢊ$ ꢅꢉꢘ(ꢇ ꢘꢈꢊ
ꢉꢊ!ꢘ ꢑꢆꢇ($ %ꢘꢆꢛꢘ ꢚ(ꢘ (% $ꢊꢘꢊ'ꢘꢊ$ꢒ
MR2n[5] - Transmitter Request-to-Send Control
ꢂꢛ$(ꢉꢆꢛ(ꢇ&" ꢘꢈꢊ ꢍꢎꢃ ꢏꢍꢊEꢅꢊ%ꢘ ꢘꢞ ꢃꢊꢉ$ꢐ ꢞꢅꢘꢗꢅꢘ (% ꢆ%%ꢊꢛꢘꢊ$
ꢞꢛ ꢉꢊ-ꢆꢘꢊ$ ꢚ& (ꢉꢑꢞ3(ꢉ- ꢘꢈꢊ Cꢃ2ꢎ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃ
ꢀꢂꢁꢁꢌ7ꢄD ꢞꢛ Cꢀ92ꢌꢍ ꢂꢋꢎ,ꢋꢎ ,ꢂꢍꢎ *#ꢎꢃ
ꢀꢂꢁꢁꢌ7ꢄD (ꢉ ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ ꢙꢆꢉꢉꢊꢛ" ꢚ& ꢘꢈꢊ %&%ꢘꢊꢙ
%ꢞ+ꢘꢝꢆꢛꢊꢒ 8ꢞꢝꢊꢑꢊꢛ" %ꢊꢘꢘ(ꢉ- ꢁꢍꢓꢉN6O J ꢔ ꢆꢇꢇꢞꢝ% ꢘꢈꢊ
ꢀꢈꢆꢉꢉꢊꢇ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢘꢞ ꢉꢊ-ꢆꢘꢊ ꢍꢎꢃ ꢆꢅꢘꢞꢙꢆꢘ('ꢆꢇꢇ&" ꢞꢉꢊ ꢚ(ꢘ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
>6
XR88C681
MR2n[3:0] - Stop Bit Length
G.4 Status Register, SRn
ꢎꢈ(% ꢚ(ꢘ +(ꢊꢇ$ ꢗꢛꢞ-ꢛꢆꢙ% ꢘꢈꢊ $ꢅꢛꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ %ꢘꢞꢗ ꢚ(ꢘ%
ꢆꢗꢗꢊꢉ$ꢊ$ ꢘꢞ ꢊꢆ'ꢈ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ 'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ ꢃꢘꢞꢗ ꢚ(ꢘ
$ꢅꢛꢆꢘ(ꢞꢉ ꢞ+ ꢖ.ꢔ/ ꢘꢞ ꢔ ꢚ(ꢘ ꢘ(ꢙꢊ ꢆꢉ$ ꢔ ꢖ.ꢔ/ ꢘꢞ ꢓ ꢚ(ꢘ ꢘ(ꢙꢊ%" (ꢉ
(ꢉ'ꢛꢊꢙꢊꢉꢘ% ꢞ+ ꢔ.ꢔ/ ꢚ(ꢘ% 'ꢆꢉ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ +ꢞꢛ 'ꢈꢆꢛꢆ'ꢘꢊꢛ
ꢇꢊꢉ-ꢘꢈ% ꢞ+ /" > ꢆꢉ$ = ꢚ(ꢘ%ꢒ ꢞꢛ ꢆ 6 ꢚ(ꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛ" ꢘꢈꢊ %ꢘꢞꢗ ꢚ(ꢘ
$ꢅꢛꢆꢘ(ꢞꢉ 'ꢆꢉ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ +ꢛꢞꢙ ꢔꢜꢔ.ꢔ/ ꢘꢞ ꢓ ꢚ(ꢘ ꢘ(ꢙꢊ%ꢒ
ꢎꢈꢊ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ ꢗꢛꢞꢑ($ꢊ% ꢘꢈꢊ ꢅ%ꢊꢛ ꢝ(ꢘꢈ %ꢘꢆꢘꢅ% ꢞꢉ ꢘꢈꢊ
ꢍ8ꢍ ꢆꢉ$ ꢎ8ꢍ ꢏꢍꢊ'ꢊ(ꢑꢊꢛ ꢆꢉ$ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ # ꢂ%"
ꢛꢊ%ꢗꢊ'ꢘ(ꢑꢊꢇ&ꢐL ꢆꢉ$ %ꢊꢛꢑꢊ% ꢘꢞ ꢗꢛꢞꢑ($ꢊ ꢘꢈꢊ ꢀ,ꢋ ꢝ(ꢘꢈ ꢆ
ꢙꢊꢆ%ꢅꢛꢊ ꢞ+ ꢘꢈꢊ Eꢅꢆꢇ(ꢘ& ꢞ+ ꢘꢈꢊ ꢛꢊ'ꢊꢗꢘ(ꢞꢉ ꢞ+ $ꢆꢘꢆ ꢚ& ꢘꢈꢊ
ꢛꢊ'ꢊ(ꢑꢊꢛꢒ # ꢂ ꢃꢘꢆꢘꢅ% (ꢉ$('ꢆꢘꢞꢛ% ꢆꢛꢊ ꢅ%ꢊ+ꢅꢇ (ꢉ ꢗꢞꢇꢇꢊ$
%&%ꢘꢊꢙ% ꢆꢉ$ ꢆꢇꢇꢞꢝ% ꢘꢈꢊ ꢀ,ꢋ ꢘꢞ 'ꢈꢊ'3 ꢆꢉ$ %ꢊꢊ (+ ꢘꢈꢊ
ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% ꢊꢙꢗꢘ& ꢆꢉ$.ꢞꢛ (% ꢛꢊꢆ$& +ꢞꢛ $ꢆꢘꢆ +ꢛꢞꢙ ꢘꢈꢊ
ꢀ,ꢋꢒ ꢎꢈꢊ # ꢂ ꢃꢘꢆꢘꢅ% (ꢉ$('ꢆꢘꢞꢛ% ꢆꢇ%ꢞ (ꢉ$('ꢆꢘꢊ ꢝꢈꢊꢘꢈꢊꢛ ꢞꢛ
ꢉꢞꢘ ꢘꢈꢊ ꢍ8ꢍ ꢈꢆ% ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ" ꢝꢈ('ꢈ (% ꢝꢆ(ꢘ(ꢉ- ꢘꢞ ꢚꢊ ꢛꢊꢆ$
ꢚ& ꢘꢈꢊ ꢀ,ꢋ" ꢞꢛ (% +ꢅꢇꢇ ꢆꢉ$ (ꢉ'ꢆꢗꢆꢚꢇꢊ ꢞ+ ꢛꢊ'ꢊ(ꢑ(ꢉ- ꢆꢉ& ꢙꢞꢛꢊ
'ꢈꢆꢛꢆ'ꢘꢊꢛ% ꢝ(ꢘꢈꢞꢅꢘ ꢆꢉ ꢞꢑꢊꢛꢛꢅꢉꢒ ꢎꢈꢊ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢆꢉ$
ꢍꢊ'ꢊ(ꢑꢊꢛ # ꢂ %ꢘꢆꢘꢅ% (ꢉ$('ꢆꢘꢞꢛ% ꢆꢛꢊ ꢇꢞ'ꢆꢘꢊ$ (ꢉ ꢘꢈꢊ ꢇꢞꢝꢊꢛ
ꢉ(ꢚꢚꢇꢊ ꢞ+ ꢘꢈꢊ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛꢒ
#+ ꢆꢉ ꢊ!ꢘꢊꢛꢉꢆꢇ ꢔ! 'ꢇꢞ'3 (% ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ +ꢞꢛ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ
'ꢇꢞ'3 ꢏꢎ5ꢀꢉꢐ" ꢁꢍꢓꢉN1O J ꢕ %ꢊꢇꢊ'ꢘ% ꢆ %ꢘꢞꢗ ꢚ(ꢘ $ꢅꢛꢆꢘ(ꢞꢉ ꢞ+
ꢞꢉꢊ ꢚ(ꢘ ꢘ(ꢙꢊ ꢆꢉ$ ꢁꢍꢓꢉN1O J ꢔ %ꢊꢇꢊ'ꢘ% ꢆ $ꢅꢛꢆꢘ(ꢞꢉ ꢞ+ ꢘꢝꢞ ꢚ(ꢘ
ꢘ(ꢙꢊ% +ꢞꢛ ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉꢒ
ꢎꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢞꢉꢇ& 'ꢈꢊ'3% +ꢞꢛ ꢙꢆꢛ3 'ꢞꢉ$(ꢘ(ꢞꢉ ꢆꢘ ꢘꢈꢊ 'ꢊꢉꢘꢊꢛ
ꢞ+ ꢘꢈꢊ +(ꢛ%ꢘ %ꢘꢞꢗ ꢚ(ꢘ ꢏꢘꢈꢆꢘ (%" ꢞꢉꢊ ꢚ(ꢘ ꢘ(ꢙꢊ ꢆ+ꢘꢊꢛ ꢘꢈꢊ ꢇꢆ%ꢘ $ꢆꢘꢆ ꢞꢛ
ꢗꢆꢛ(ꢘ& ꢚ(ꢘ (% %ꢆꢙꢗꢇꢊ$ꢐ ꢛꢊ-ꢆꢛ$ꢇꢊ%% ꢞ+ ꢘꢈꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$
ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ %ꢘꢞꢗ ꢚ(ꢘ ꢇꢊꢉ-ꢘꢈꢒ #+ ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊꢛ $ꢞꢊ% ꢉꢞꢘ %ꢆꢙꢗꢇꢊ
ꢆ Cꢙꢆꢛ3D ꢆ C ꢛꢆꢙꢊ 2ꢛꢛꢞꢛD ꢏ 2ꢐ (% +ꢇꢆ--ꢊ$ (ꢉ ꢘꢈꢊ ꢃꢘꢆꢘꢅ%
ꢍꢊ-(%ꢘꢊꢛꢒ
ꢎꢈꢊ ꢅꢗꢗꢊꢛ ꢉ(ꢚꢚꢇꢊ ꢞ+ ꢘꢈꢊ ꢃꢘꢆꢘꢅ% ꢍꢊ-(%ꢘꢊꢛ ꢆꢇꢊꢛꢘ% ꢘꢈꢊ ꢅ%ꢊꢛ ꢞ+
ꢆꢉ& $ꢆꢘꢆ ꢛꢊ'ꢊꢗꢘ(ꢞꢉ ꢊꢛꢛꢞꢛ%ꢒ ꢎꢈꢊ ꢚ(ꢘꢜ+ꢞꢛꢙꢆꢘ ꢞ+ ꢘꢈꢊ ꢃꢘꢆꢘꢅ%
ꢍꢊ-(%ꢘꢊꢛ ꢆꢉ$ ꢆ $(%'ꢅ%%(ꢞꢉ ꢞ+ ꢊꢆ'ꢈ ꢚ(ꢘ +ꢞꢇꢇꢞꢝ%4
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Received
Break
Framing Error Parity Error
Overrun
Error
TXEMT
TXRDY
FFULL
RXRDY
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
Table 28. Status Register - SRA, SRB
SRn[7] Received Break
(ꢉꢗꢅꢘ (% ꢚꢛꢞꢅ-ꢈꢘ ꢘꢞ ꢆ ꢇꢞ-(' Cꢈ(-ꢈD ꢇꢊꢑꢊꢇ" (ꢉ ꢘꢈꢊ ꢉꢊ!ꢘ
'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ
ꢎꢈ(% ꢚ(ꢘ (ꢉ$('ꢆꢘꢊ% ꢘꢈꢆꢘ ꢆꢉ ꢆꢇꢇ Iꢊꢛꢞ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢞ+ ꢘꢈꢊ
ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢇꢊꢉ-ꢘꢈ ꢝꢆ% ꢛꢊ'ꢊ(ꢑꢊ$ ꢝ(ꢘꢈꢞꢅꢘ ꢆ
%ꢘꢞꢗ ꢚ(ꢘꢒ ꢂꢉꢇ& ꢆ %(ꢉ-ꢇꢊ # ꢂ ꢗꢞ%(ꢘ(ꢞꢉ (% ꢞ''ꢅꢗ(ꢊ$ ꢝꢈꢊꢉ ꢆ
ꢚꢛꢊꢆ3 (% ꢛꢊ'ꢊ(ꢑꢊ$ꢒ ꢌ$$(ꢘ(ꢞꢉꢆꢇ ꢘꢛꢆꢉ%+ꢊꢛ% (ꢉꢘꢞ ꢘꢈꢊ # ꢂ ꢆꢛꢊ
(ꢉꢈ(ꢚ(ꢘꢊ$ ꢅꢉꢘ(ꢇ ꢘꢈꢊ ꢍ5ꢄ ꢇ(ꢉꢊ ꢛꢊꢘꢅꢛꢉ% ꢘꢞ ꢘꢈꢊ ꢙꢆꢛ3(ꢉ- %ꢘꢆꢘꢊ +ꢞꢛ
ꢆꢘ ꢇꢊꢆ%ꢘ ꢈꢆꢇ+ ꢆ ꢚ(ꢘ ꢘ(ꢙꢊꢒ ꢎꢈ(% (% $ꢊ+(ꢉꢊ$ ꢆ% ꢘꢝꢞ %ꢅ''ꢊ%%(ꢑꢊ
ꢊ$-ꢊ% ꢞ+ ꢘꢈꢊ (ꢉꢘꢊꢛꢉꢆꢇ ꢞꢛ ꢊ!ꢘꢊꢛꢉꢆꢇ ꢔ! 'ꢇꢞ'3ꢒ
#+ ꢘꢈꢊ C2ꢛꢛꢞꢛD ꢁꢞ$ꢊ ꢈꢆ% ꢚꢊꢊꢉ %ꢊꢘ ꢘꢞ C*ꢇꢞ'3D ꢙꢞ$ꢊ" ꢘꢈꢊꢉ ꢘꢈ(%
ꢚ(ꢘ" ꢞꢉ'ꢊ %ꢊꢘ ꢝ(ꢇꢇ ꢛꢊꢙꢆ(ꢉ ꢆ%%ꢊꢛꢘꢊ$ ꢅꢉꢘ(ꢇ ꢘꢈꢊ Cꢍ2ꢃ2ꢎ
2ꢍꢍꢂꢍ ꢃꢎꢌꢎꢋꢃD 'ꢞꢙꢙꢆꢉ$ ꢈꢆ% ꢚꢊꢊꢉ (ꢉꢑꢞ3ꢊ$ ꢏꢗꢇꢊꢆ%ꢊ
%ꢊꢊ Table 3ꢐꢒ Please note that if the Error Mode is “Block”
this bit, in the Status Register will remain set, for all
subsequent characters, independent of the condition of
these received characters, until the “RESET ERROR
STATUS” command has been invoked.
Bꢈꢊꢉ ꢘꢈ(% ꢚ(ꢘ (% %ꢊꢘ" ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇH% Cꢀ8ꢌ702 #7 *ꢍ2ꢌ:
ꢃꢎꢌꢎꢋꢃD ꢚ(ꢘ (ꢉ ꢘꢈꢊ #ꢃꢍ (% %ꢊꢘꢒ ꢎꢈꢊ ꢚ(ꢘ (ꢉ ꢘꢈꢊ #ꢃꢍ (% ꢆꢇ%ꢞ %ꢊꢘ
ꢝꢈꢊꢉ ꢘꢈꢊ ꢊꢉ$ ꢞ+ ꢘꢈꢊ ꢚꢛꢊꢆ3 'ꢞꢉ$(ꢘ(ꢞꢉ" ꢆ% $ꢊ+(ꢉꢊ$ ꢆꢚꢞꢑꢊ" (%
$ꢊꢘꢊ'ꢘꢊ$ꢒ
SRn[6] Framing Error
ꢞꢇꢇꢞꢝ(ꢉ- ꢛꢊ'ꢊꢗꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢚ(ꢘ%" ꢆꢉ$ ꢆꢉ&
ꢆ%%ꢞ'(ꢆꢘꢊ$ ꢗꢆꢛ(ꢘ& ꢚ(ꢘ" ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢝ(ꢇꢇ 'ꢈꢊ'3 +ꢞꢛ ꢆ Cꢙꢆꢛ3D
'ꢞꢉ$(ꢘ(ꢞꢉ ꢞꢉꢊ ꢚ(ꢘꢜꢘ(ꢙꢊ +ꢞꢇꢇꢞꢝ(ꢉ- ꢘꢈꢊ ꢇꢆ%ꢘ $ꢆꢘꢆ ꢞꢛ ꢗꢆꢛ(ꢘ& ꢚ(ꢘꢒ
ꢎꢈ(% Cꢙꢆꢛ3D 'ꢞꢉ$(ꢘ(ꢞꢉ (% ꢘꢈꢊ ꢃꢎꢂ, ꢚ(ꢘꢒ #+ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ
$ꢞꢊ% ꢉꢞꢘ $ꢊꢘꢊ'ꢘ ꢆ Cꢙꢆꢛ3D ꢆꢘ ꢘꢈ(% ꢘ(ꢙꢊ" ꢘꢈꢊ ꢚ(ꢘ (% ꢘꢞ--ꢇꢊ$
Cꢈ(-ꢈD +ꢇꢆ--(ꢉ- ꢘꢈꢊ ꢞ''ꢅꢛꢛꢊꢉ'ꢊ ꢞ+ ꢆ ꢛꢆꢙꢊ 2ꢛꢛꢞꢛ ꢏ 2ꢐꢒ
ꢎꢈꢊ 'ꢈ(ꢗH% ꢚꢛꢊꢆ3 $ꢊꢘꢊ'ꢘ ꢇꢞ-(' 'ꢆꢉ $ꢊꢘꢊ'ꢘ ꢚꢛꢊꢆ3% ꢘꢈꢆꢘ ꢚꢊ-(ꢉ
(ꢉ ꢘꢈꢊ ꢙ($$ꢇꢊ ꢞ+ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ 8ꢞꢝꢊꢑꢊꢛ" ꢘꢈꢊ ꢚꢛꢊꢆ3 ꢙꢅ%ꢘ
ꢗꢊꢛ%(%ꢘ ꢅꢉꢘ(ꢇ ꢘꢈꢊ ꢊꢉ$ ꢞ+ ꢘꢈꢊ ꢉꢊ!ꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢘ(ꢙꢊ (ꢉ ꢞꢛ$ꢊꢛ +ꢞꢛ (ꢘ
ꢘꢞ ꢚꢊ $ꢊꢘꢊ'ꢘꢊ$ꢒ
#+ ꢘꢈꢊ 2ꢛꢛꢞꢛ ꢁꢞ$ꢊ" ꢞ+ ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇ" ꢈꢆ% ꢚꢊꢊꢉ %ꢊꢘ ꢘꢞ
Cꢀꢈꢆꢛꢆ'ꢘꢊꢛD ꢁꢞ$ꢊ" ꢘꢈ(% ꢚ(ꢘ ꢞꢉꢇ& ꢆꢗꢗꢇ(ꢊ% ꢘꢞ ꢘꢈꢊ ꢀꢈꢆꢛꢆ'ꢘꢊꢛ ꢆꢘ
ꢘꢈꢊ ꢘꢞꢗ ꢞ+ ꢘꢈꢊ ꢍ8ꢍꢒ ꢎꢈ(% ꢚ(ꢘ ꢝ(ꢇꢇ ꢚꢊ 'ꢇꢊꢆꢛꢊ$ (+ ꢘꢈꢊ ꢍ5ꢄꢉ
#+ ꢘꢈꢊ 2ꢛꢛꢞꢛ ꢁꢞ$ꢊ ꢈꢆ% ꢚꢊꢊꢉ %ꢊꢘ ꢘꢞ Cꢀꢈꢆꢛꢆ'ꢘꢊꢛD ꢁꢞ$ꢊ" ꢘꢈ(%
ꢚ(ꢘ ꢞꢉꢇ& ꢆꢗꢗꢇ(ꢊ% ꢘꢞ ꢘꢈꢊ ꢀꢈꢆꢛꢆ'ꢘꢊꢛ ꢆꢘ ꢘꢈꢊ ꢘꢞꢗ ꢞ+ ꢘꢈꢊ ꢍ8ꢍꢒ #+
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
>/
XR88C681
ꢘꢈ(% ꢚ(ꢘ (% %ꢊꢘ +ꢞꢛ ꢆ -(ꢑꢊꢉ 'ꢈꢆꢛꢆ'ꢘꢊꢛ" (ꢘ ꢝ(ꢇꢇ ꢚꢊ 'ꢇꢊꢆꢛꢊ$ (+ ꢘꢈꢊ
ꢃꢎꢂ, ꢚ(ꢘ (% ꢗꢛꢞꢗꢊꢛꢇ& $ꢊꢘꢊ'ꢘꢊ$ (ꢉ ꢘꢈꢊ ꢉꢊ!ꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ
SRn[3] Transmitter Empty (TXEMT)
ꢎꢈ(% ꢚ(ꢘ (% %ꢊꢘ ꢝꢈꢊꢉ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢅꢉ$ꢊꢛꢛꢅꢉ%ꢒ #ꢘ (% %ꢊꢘ
ꢆ+ꢘꢊꢛ ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢇꢆ%ꢘ %ꢘꢞꢗ ꢚ(ꢘ ꢞ+ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢆꢉ$ (+
ꢘꢈꢊꢛꢊ (% ꢉꢞ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (ꢉ ꢘꢈꢊ ꢎ8ꢍ ꢞꢛ ꢎꢃꢍ ꢆꢝꢆ(ꢘ(ꢉ-
ꢘꢛꢆꢉ%ꢙ(%%(ꢞꢉꢒ ꢎꢈ(% ꢚ(ꢘ (% 'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (%
$(%ꢆꢚꢇꢊ$" ꢞꢛ ꢝꢈꢊꢉ ꢘꢈꢊ ꢀ,ꢋ ꢝꢛ(ꢘꢊ% ꢆ ꢉꢊꢝ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢘꢞ ꢘꢈꢊ
ꢎ8ꢍꢒ
#+ ꢘꢈꢊ C2ꢛꢛꢞꢛD ꢁꢞ$ꢊ ꢈꢆ% ꢚꢊꢊꢉ %ꢊꢘ ꢘꢞ C*ꢇꢞ'3D ꢙꢞ$ꢊ" ꢘꢈꢊꢉ ꢘꢈ(%
ꢚ(ꢘ" ꢞꢉ'ꢊ %ꢊꢘ ꢝ(ꢇꢇ ꢛꢊꢙꢆ(ꢉ ꢆ%%ꢊꢛꢘꢊ$ ꢅꢉꢘ(ꢇ ꢘꢈꢊ Cꢍ2ꢃ2ꢎ
2ꢍꢍꢂꢍ ꢃꢎꢌꢎꢋꢃD 'ꢞꢙꢙꢆꢉ$ ꢈꢆ% ꢚꢊꢊꢉ (ꢉꢑꢞ3ꢊ$ ꢏꢗꢇꢊꢆ%ꢊ
%ꢊꢊ Table 3ꢐꢒ Please note that if the Error Mode is “Block”
this bit, in the Status Register will remain set, for all
subsequent characters, independent of the condition of
these received characters, until the “RESET ERROR
STATUS” command has been invoked.
SRn[2] Transmitter Ready (TXRDY)
ꢎꢈ(% ꢚ(ꢘ" ꢝꢈꢊꢉ %ꢊꢘ" (ꢉ$('ꢆꢘꢊ% ꢘꢈꢆꢘ ꢘꢈꢊ ꢎ8ꢍ (% ꢊꢙꢗꢘ& ꢆꢉ$
ꢛꢊꢆ$& ꢘꢞ ꢆ''ꢊꢗꢘ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ +ꢛꢞꢙ ꢘꢈꢊ ꢀ,ꢋꢒ ꢎꢈꢊ ꢚ(ꢘ (%
'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ ꢀ,ꢋ ꢝꢛ(ꢘꢊ% ꢆ ꢉꢊꢝ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢘꢞ ꢘꢈꢊ ꢎ8ꢍ"
ꢆꢉ$ (% %ꢊꢘ ꢝꢈꢊꢉ ꢘꢈꢆꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢘꢛꢆꢉ%+ꢊꢛꢛꢊ$ ꢘꢞ ꢘꢈꢊ ꢎꢃꢍꢒ
ꢎ5ꢍꢄG (% %ꢊꢘ ꢝꢈꢊꢉ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% (ꢉ(ꢘ(ꢆꢇꢇ& ꢊꢉꢆꢚꢇꢊ$ ꢆꢉ$
(% ꢛꢊ%ꢊꢘ ꢝꢈꢊꢉ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% $(%ꢆꢚꢇꢊ$ꢒ ꢀꢈꢆꢛꢆ'ꢘꢊꢛ%
ꢇꢞꢆ$ꢊ$ (ꢉꢘꢞ ꢘꢈꢊ ꢎ8ꢍ ꢝꢈ(ꢇꢊ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ (% $(%ꢆꢚꢇꢊ$ ꢝ(ꢇꢇ
ꢉꢞꢘ ꢚꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ꢒ
SRn[5] Parity Error
ꢎꢈ(% ꢚ(ꢘ (% %ꢊꢘ ꢝꢈꢊꢉ ꢘꢈꢊ CB#ꢎ8 ,ꢌꢍ#ꢎGD ꢞꢛ C ꢂꢍꢀ2
,ꢌꢍ#ꢎGD ꢙꢞ$ꢊ% ꢆꢛꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢆꢉ$ (+ ꢘꢈꢊ
'ꢞꢛꢛꢊ%ꢗꢞꢉ$(ꢉ- 'ꢈꢆꢛꢆ'ꢘꢊꢛ (ꢉ ꢘꢈꢊ $ꢆꢘꢆ # ꢂ ꢝꢆ% ꢛꢊ'ꢊ(ꢑꢊ$
ꢝ(ꢘꢈ (ꢉ'ꢞꢛꢛꢊ'ꢘ ꢗꢆꢛ(ꢘ&ꢒ
#+ ꢘꢈꢊ 2ꢛꢛꢞꢛ ꢁꢞ$ꢊ ꢈꢆ% ꢚꢊꢊꢉ %ꢊꢘ ꢘꢞ Cꢀꢈꢆꢛꢆ'ꢘꢊꢛD ꢁꢞ$ꢊ" ꢘꢈ(%
ꢚ(ꢘ ꢞꢉꢇ& ꢆꢗꢗꢇ(ꢊ% ꢘꢞ ꢘꢈꢊ ꢀꢈꢆꢛꢆ'ꢘꢊꢛ ꢆꢘ ꢘꢈꢊ ꢘꢞꢗ ꢞ+ ꢘꢈꢊ ꢍ8ꢍꢒ #+
ꢘꢈ(% ꢚ(ꢘ (% %ꢊꢘ +ꢞꢛ ꢆ -(ꢑꢊꢉ 'ꢈꢆꢛꢆ'ꢘꢊꢛ" (ꢘ ꢝ(ꢇꢇ ꢚꢊ 'ꢇꢊꢆꢛꢊ$ (+ ꢘꢈꢊ
ꢛꢊ'ꢊ(ꢑꢊ$ ꢗꢆꢛ(ꢘ& (% 'ꢞꢛꢛꢊ'ꢘ (ꢉ ꢘꢈꢊ ꢉꢊ!ꢘ 'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ
SRn[1] FIFO Full (FFULL)
ꢎꢈ(% ꢚ(ꢘ (% %ꢊꢘ ꢝꢈꢊꢉ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢘꢛꢆꢉ%+ꢊꢛꢛꢊ$ +ꢛꢞꢙ ꢘꢈꢊ
ꢍꢃꢍ ꢘꢞ ꢘꢈꢊ ꢍ8ꢍ ꢆꢉ$ ꢘꢈꢊ ꢘꢛꢆꢉ%+ꢊꢛ 'ꢆꢅ%ꢊ% (ꢘ ꢘꢞ ꢚꢊ'ꢞꢙꢊ +ꢅꢇꢇ"
(ꢒꢊꢒ" ꢆꢇꢇ ꢘꢈꢛꢊꢊ # ꢂ ꢗꢞ%(ꢘ(ꢞꢉ% ꢆꢛꢊ ꢞ''ꢅꢗ(ꢊ$ꢒ #ꢘ (% ꢛꢊ%ꢊꢘ ꢝꢈꢊꢉ
ꢘꢈꢊ ꢀ,ꢋ ꢛꢊꢆ$% ꢘꢈꢊ ꢍ8ꢍꢒ #+ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢝꢆ(ꢘ(ꢉ- (ꢉ ꢘꢈꢊ
ꢍꢃꢍ ꢚꢊ'ꢆꢅ%ꢊ ꢘꢈꢊ # ꢂ (% +ꢅꢇꢇ" ꢋ99 ꢝ(ꢇꢇ ꢉꢞꢘ ꢚꢊ ꢛꢊ%ꢊꢘ
ꢝꢈꢊꢉ ꢘꢈꢊ ꢀ,ꢋ ꢛꢊꢆ$% ꢘꢈꢊ ꢍ8ꢍꢒ
#+ ꢘꢈꢊ C2ꢛꢛꢞꢛD ꢁꢞ$ꢊ ꢈꢆ% ꢚꢊꢊꢉ %ꢊꢘ ꢘꢞ C*ꢇꢞ'3D ꢙꢞ$ꢊ" ꢘꢈꢊꢉ ꢘꢈ(%
ꢚ(ꢘ" ꢞꢉ'ꢊ %ꢊꢘ ꢝ(ꢇꢇ ꢛꢊꢙꢆ(ꢉ ꢆ%%ꢊꢛꢘꢊ$ ꢅꢉꢘ(ꢇ ꢘꢈꢊ Cꢍ2ꢃ2ꢎ
2ꢍꢍꢂꢍ ꢃꢎꢌꢎꢋꢃD 'ꢞꢙꢙꢆꢉ$ ꢈꢆ% ꢚꢊꢊꢉ (ꢉꢑꢞ3ꢊ$ ꢏꢗꢇꢊꢆ%ꢊ
%ꢊꢊ Table 3ꢐꢒ Please note that if the Error Mode is “Block”
this bit, in the Status Register will remain set, for all
subsequent characters, independent of the condition of
these received characters, until the “RESET ERROR
STATUS” command has been invoked.
SRn[0] Receiver Ready (RXRDY)
ꢎꢈ(% ꢚ(ꢘ (ꢉ$('ꢆꢘꢊ% ꢘꢈꢆꢘ ꢆꢘ ꢇꢊꢆ%ꢘ ꢞꢉꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢈꢆ% ꢚꢊꢊꢉ
ꢛꢊ'ꢊ(ꢑꢊ$ ꢆꢉ$ (% ꢝꢆ(ꢘ(ꢉ- (ꢉ ꢘꢈꢊ # ꢂ ꢘꢞ ꢚꢊ ꢛꢊꢆ$ ꢚ& ꢘꢈꢊ ꢀ,ꢋꢒ
#ꢘ (% %ꢊꢘ ꢝꢈꢊꢉ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛ (% ꢘꢛꢆꢉ%+ꢊꢛꢛꢊ$ +ꢛꢞꢙ ꢘꢈꢊ ꢍꢃꢍ ꢘꢞ
ꢘꢈꢊ ꢍ8ꢍ ꢆꢉ$ (% 'ꢇꢊꢆꢛꢊ$ ꢝ(ꢘꢈ ꢘꢈꢊ ꢀ,ꢋ ꢛꢊꢆ$% ꢘꢈꢊ ꢇꢆ%ꢘ
'ꢈꢆꢛꢆ'ꢘꢊꢛ 'ꢅꢛꢛꢊꢉꢘꢇ& %ꢘꢞꢛꢊ$ (ꢉ ꢘꢈꢊ # ꢂꢒ
SRn[4] Overrun Error
Please note that some of the conditions that are flagged
by the Status Register can also be programmed to
generate an Interrupt Request to the CPU. 8ꢞꢝꢊꢑꢊꢛ"
ꢘꢈꢊꢛꢊ ꢆꢛꢊ %ꢞꢙꢊ 'ꢞꢉ$(ꢘ(ꢞꢉ% ꢘꢈꢆꢘ ꢆꢛꢊ +ꢇꢆ--ꢊ$ ꢚ& ꢘꢈꢊ ꢃꢘꢆꢘꢅ%
ꢍꢊ-(%ꢘꢊꢛ ꢘꢈꢆꢘ 'ꢆꢉꢉꢞꢘ ꢚꢊ ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢘꢞ -ꢊꢉꢊꢛꢆꢘꢊ ꢆꢉ
#ꢉꢘꢊꢛꢛꢅꢗꢘꢒ ꢎꢈꢊ%ꢊ 'ꢞꢉ$(ꢘ(ꢞꢉ% ꢆꢛꢊ ꢇ(%ꢘꢊ$ ꢈꢊꢛꢊ4
#+ %ꢊꢘ" ꢘꢈ(% ꢚ(ꢘ (ꢉ$('ꢆꢘꢊ% ꢘꢈꢆꢘ ꢞꢉꢊ ꢞꢛ ꢙꢞꢛꢊ 'ꢈꢆꢛꢆ'ꢘꢊꢛ% (ꢉ ꢘꢈꢊ
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Please note that unlike the Status Register bits for FE
(Framing Error), PE (Parity Error) and RB (Received
Break), the OE (Overrun Error) indicator is always flagged
on a “Block” Error Mode basisꢒ ꢎꢈꢊ ꢂ2 'ꢞꢉ$(ꢘ(ꢞꢉ (% ꢉꢊꢑꢊꢛ
+ꢇꢆ--ꢊ$ ꢞꢉ ꢆ 'ꢈꢆꢛꢆ'ꢘꢊꢛꢜꢘꢞꢜ'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢚꢆ%(%" ꢆꢉ$ ꢞꢉꢇ&
'ꢇꢊꢆꢛꢊ$ ꢝꢈꢊꢉ ꢘꢈꢊ Cꢍ2ꢃ2ꢎ 2ꢍꢍꢂꢍ ꢃꢎꢌꢎꢋꢃD 'ꢞꢙꢙꢆꢉ$ (%
(ꢉꢑꢞ3ꢊ$ꢒ
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ꢁ ꢃꢍꢉN<O ꢜ ꢂꢑꢊꢛꢛꢅꢉ 2ꢛꢛꢞꢛ
ꢎꢈꢊꢛꢊ+ꢞꢛꢊ" (+ %&%ꢘꢊꢙ ꢇꢊꢑꢊꢇ ꢊꢛꢛꢞꢛꢜ'ꢈꢊ'3(ꢉ- (% ꢉꢞꢘ ꢊꢙꢗꢇꢞ&ꢊ$"
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ꢍꢊꢑꢒ ꢓꢒꢔꢕ
>>
XR88C681
H. SPECIAL MODES OF OPERATION
H.1 RTS/CTS Handshaking
H.1.1 Receiver-Controlled RTS/CTS Handshaking
#ꢉ ꢘꢈ(% ꢙꢞ$ꢊ" ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢈꢆ% ꢘꢈꢊ ꢆꢚ(ꢇ(ꢘ& ꢘꢞ ꢆꢅꢘꢞꢙꢆꢘ('ꢆꢇꢇ&
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ꢗꢛꢊ%ꢊꢉꢘ% ꢆ $(ꢆ-ꢛꢆꢙ ꢞ+ ꢆꢉ ꢊ!ꢆꢙꢗꢇꢊ (ꢇꢇꢅ%ꢘꢛꢆꢘ(ꢉ- ꢘꢈꢊ
Figure 42
ꢞꢗꢊꢛꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛꢜꢀꢞꢉꢘꢛꢞꢇꢇꢊ$ ꢍꢎꢃ 'ꢞꢉ+(-ꢅꢛꢆꢘ(ꢞꢉꢒ
ꢁ ꢍꢊ'ꢊ(ꢑꢊꢛꢜꢀꢞꢉꢘꢛꢞꢇꢇꢊ$ ꢍꢎꢃ.ꢀꢎꢃ 8ꢆꢉ$%ꢈꢆ3(ꢉ-
ꢁ ꢎꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛꢜꢀꢞꢉꢘꢛꢞꢇꢇꢊ$ ꢍꢎꢃ.ꢀꢎꢃ 8ꢆꢉ$%ꢈꢆ3(ꢉ-
ꢍꢊ'ꢊ(ꢑ(ꢉ- ꢄꢊꢑ('ꢊ
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ꢍꢎꢃꢌ
ꢏꢂ,ꢕꢐ
ꢀꢎꢃ*
ꢏ#,ꢔꢐ
ꢍ5ꢄꢌ
ꢎ5ꢄ*
ꢎ5ꢄꢌ
ꢍ5ꢄ*
ꢀꢎꢃꢌ
ꢏ#,ꢕꢐ
ꢍꢎꢃ*
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ꢋ99ꢌ
ꢏꢂ,<ꢐ
ꢎꢞ ꢀ,ꢋ
ꢋ99ꢌ
ꢍꢎꢃꢌ
ꢍ5ꢄꢌ
Figure 42. Block Diagram and Timing Sequence of Two DUARTs Connected
in the Receiver-RTS Controlled Configuration
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
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XR88C681
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Figure 43. A Flow Diagram Depicting an Algorithm That Could be Used to Apply
the Receiver-Controlled RTS/CTS Handshaking Mode
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ꢜꢀꢎꢃꢌ #7,ꢋꢎ #ꢃ 720ꢌꢎ2ꢄꢒ
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#%
ꢎ5ꢍꢄG
7ꢊ-ꢆꢘꢊ$T
7ꢞ
Gꢊ%
Figure 45. A Flow Diagram depicting an Algorithm that could be used to Realize the
Transmitter-Controlled RTS/CTS Handshaking Mode
H.2 Multi-drop (8051 9 bit) Mode
H.2.1 Concept of Multi-Drop Mode
2ꢆ'ꢈ %ꢊꢛ(ꢆꢇ 'ꢈꢆꢉꢉꢊꢇ ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ 'ꢆꢉ ꢚꢊ 'ꢞꢉ+(-ꢅꢛꢊ$ ꢘꢞ
ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢆ ꢝꢆ3ꢊ ꢅꢗ ꢙꢞ$ꢊ ꢅ%ꢊ+ꢅꢇ +ꢞꢛ ꢙꢅꢇꢘ(ꢜ$ꢛꢞꢗ ꢞꢛ
ꢙꢅꢇꢘ(ꢗꢛꢞ'ꢊ%%ꢞꢛ ꢆꢗꢗꢇ('ꢆꢘ(ꢞꢉ%ꢒ ꢎꢈ(% %ꢊ'ꢘ(ꢞꢉ ꢝ(ꢇꢇ +(ꢛ%ꢘ ꢗꢛꢊ%ꢊꢉꢘ
ꢘꢈꢊ 'ꢞꢉ'ꢊꢗꢘ ꢞ+ ꢘꢈꢊ ꢁꢅꢇꢘ(ꢜꢄꢛꢞꢗ ꢁꢞ$ꢊꢒ ꢌ+ꢘꢊꢛꢝꢆꢛ$%" ꢘꢈꢊ
+ꢅꢉ'ꢘ(ꢞꢉ ꢆꢉ$ ꢗꢛꢞ'ꢊ$ꢅꢛꢊ ꢞ+ ꢞꢗꢊꢛꢆꢘ(ꢉ- ꢘꢈꢊ ꢄꢋꢌꢍꢎ (ꢉ ꢘꢈꢊ
ꢁꢅꢇꢘ(ꢜꢄꢛꢞꢗ ꢙꢞ$ꢊ (% $(%'ꢅ%%ꢊ$ (ꢉ Section H.2.1ꢒ
ꢎꢈ(% ꢙꢞ$ꢊ (% 'ꢞꢙꢗꢆꢘ(ꢚꢇꢊ ꢝ(ꢘꢈ ꢘꢈꢊ %ꢊꢛ(ꢆꢇ C7(ꢉꢊ ꢚ(ꢘ ꢁꢞ$ꢊD ꢞ+
=ꢕ6ꢔ +ꢆꢙ(ꢇ& ꢙ('ꢛꢞ'ꢞꢙꢗꢅꢘꢊꢛ%ꢒ #ꢉ ꢘꢈ(% ꢙꢞ$ꢊ ꢞ+ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ ꢆ
Cꢙꢆ%ꢘꢊꢛ %ꢘꢆꢘ(ꢞꢉD" 'ꢞꢉꢉꢊ'ꢘꢊ$ ꢘꢞ ꢆ ꢙꢆ!(ꢙꢅꢙ ꢞ+ ꢓ6/ %ꢇꢆꢑꢊ
%ꢘꢆꢘ(ꢞꢉ (% ꢗꢞ%%(ꢚꢇꢊ" ꢆ% $ꢊꢗ('ꢘꢊ$ (ꢉ Figure 46ꢒ
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
=1
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ꢎ5ꢄꢉ
ꢍ5ꢄꢉ
ꢍ5ꢄꢉ
ꢍ5ꢄꢉ
ꢍ5ꢄꢉ
ꢈ
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ꢕꢔꢈ
ꢕꢓꢈ
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Figure 46. An Illustration Depicting the Concept of Multi-Drop Mode
9ꢃ*
ꢁꢃ* ꢌ.ꢄ
= *(ꢘ ꢀꢈꢆꢛꢆ'ꢘꢊꢛ
ꢌ$$ꢛꢊ%%.ꢄꢆꢘꢆ *(ꢘ
Figure 47. Bit Format of Character Data Being Transmitted in the Multi-Drop Mode
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$ꢆꢘꢆ ꢘꢞ ꢞꢉꢊ ꢞ+ %ꢊꢑꢊꢛꢆꢇ %ꢇꢆꢑꢊ%" (ꢘ +(ꢛ%ꢘ %ꢊꢉ$% ꢞꢅꢘ ꢆꢉ ꢌ$$ꢛꢊ%%
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$(++ꢊꢛ% +ꢛꢞꢙ ꢆ $ꢆꢘꢆ ꢚ&ꢘꢊ (ꢉ ꢘꢈꢆꢘ ꢘꢈꢊ ꢉ(ꢉꢘꢈ ꢚ(ꢘ (% ꢆ CꢔD (ꢉ ꢆꢉ
ꢌ$$ꢛꢊ%% *&ꢘꢊ ꢆꢉ$ ꢆ CꢕD (ꢉ ꢆ ꢄꢆꢘꢆ *&ꢘꢊꢒ
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ꢆꢉ Cꢌ$$ꢛꢊ%%.ꢄꢆꢘꢆD ꢚ(ꢘ +ꢇꢆ- ꢆꢗꢗꢊꢉ$ꢊ$ ꢘꢞ ꢘꢈꢊ ꢊꢉ$ ꢞ+ ꢘꢈꢊ
'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ ꢎꢈ(% ꢘ&ꢗ('ꢆꢇꢇ& ꢛꢊ%ꢅꢇꢘ% (ꢉ ꢉ(ꢉꢊ ꢚ(ꢘ% ꢞ+ ꢚꢊ(ꢉ-
ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊ$ +ꢞꢛ ꢊꢑꢊꢛ& 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢚ&ꢘꢊ" ꢆ% ꢗꢛꢊ%ꢊꢉꢘꢊ$ (ꢉ
Figure 47ꢒ
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ꢞ+ ꢘꢈꢊ ꢆ$$ꢛꢊ%%ꢊ$ %ꢇꢆꢑꢊ ꢝ(ꢇꢇ ꢚꢊ ꢊꢉꢆꢚꢇꢊ$ ꢆꢉ$ ꢝ(ꢇꢇ ꢗꢛꢊꢗꢆꢛꢊ +ꢞꢛ
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Transmitter Operation During Multi-Drop Mode
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H.2.2 DUART Multi-Drop Operation
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ꢃꢎꢌꢍꢎ
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,ꢂ#7ꢎ2ꢍD 'ꢞꢙꢙꢆꢉ$ꢒ
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7ꢞ
Figure 48. A Flow Diargam Depicting a Procedure That Can Be Used to
Transmit Characters in the Multi-Drop Mode
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
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Receiver Operation During Multi-Drop Mode
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%ꢈꢞꢅꢇ$ ꢘꢈꢊꢉ ꢛꢊꢆ$ ꢘꢈꢊ ꢛꢊ'ꢊ(ꢑꢊ$ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢆꢉ$ $ꢊꢘꢊꢛꢙ(ꢉꢊ (+
ꢘꢈꢊ ꢆ$$ꢛꢊ%% ꢘꢈꢆꢘ (ꢘ ꢛꢊꢗꢛꢊ%ꢊꢉꢘ% ꢙꢆꢘ'ꢈꢊ% ꢘꢈꢆꢘ ꢞ+ ꢘꢈꢊ ꢀ,ꢋꢒ #+
ꢘꢈꢊ ꢌ$$ꢛꢊ%%ꢊ% $ꢞ ꢙꢆꢘ'ꢈ" ꢏ(ꢉ$('ꢆꢘ(ꢉ- ꢘꢈꢆꢘ (ꢘ (% ꢘꢈꢊ ꢎꢆꢛ-ꢊꢘ
ꢃꢇꢆꢑꢊꢐ" ꢘꢈꢊꢉ ꢘꢈꢊ ꢀ,ꢋ %ꢈꢞꢅꢇ$ ꢊꢉꢆꢚꢇꢊ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ" (ꢉ
ꢗꢛꢊꢗꢆꢛꢆꢘ(ꢞꢉ +ꢞꢛ ꢘꢈꢊ %ꢅꢚ%ꢊEꢅꢊꢉꢘ ꢚꢇꢞ'3% ꢞ+ $ꢆꢘꢆꢒ
ꢂꢉ'ꢊ ꢘꢈꢊ Cꢎꢆꢛ-ꢊꢘ ꢀ,ꢋD $ꢊꢘꢊ'ꢘ% ꢆ ꢉꢊꢝ ꢆ$$ꢛꢊ%% 'ꢈꢆꢛꢆ'ꢘꢊꢛ"
ꢃꢍꢉN6O JCꢔD" (ꢘ %ꢈꢞꢅꢇ$ 'ꢞꢙꢗꢆꢛꢊ ꢘꢈ(% ꢆ$$ꢛꢊ%% ꢝ(ꢘꢈ (ꢘ% ꢞꢝꢉꢒ
#+ ꢘꢈꢊ ꢆ$$ꢛꢊ%%ꢊ% $ꢞ ꢉꢞꢘ ꢙꢆꢘ'ꢈ" ꢘꢈꢊꢉ ꢘꢈ(% ꢀ,ꢋ (% ꢉꢞꢘ ꢘꢈꢊ
(ꢉꢘꢊꢉ$ꢊ$ ꢛꢊ'(ꢗ(ꢊꢉꢘ ꢞ+ ꢘꢈꢊ ꢉꢊ!ꢘ ꢚꢇꢞ'3 ꢞ+ $ꢆꢘꢆ" ꢆꢉ$ ꢉꢞꢝ
%ꢈꢞꢅꢇ$ $(%ꢆꢚꢇꢊ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛꢒ Figure 49 ꢗꢛꢊ%ꢊꢉꢘ% ꢆ +ꢇꢞꢝ
$(ꢆ-ꢛꢆꢙ $ꢊꢗ('ꢘ(ꢉ-
ꢆ ꢛꢊ'ꢞꢙꢙꢊꢉ$ꢊ$ ꢗꢛꢞ'ꢊ$ꢅꢛꢊ +ꢞꢛ
ꢈꢆꢉ$ꢇ(ꢉ- ꢛꢊ'ꢊ(ꢑꢊ$ 'ꢈꢆꢛꢆ'ꢘꢊꢛ% ꢝꢈ(ꢇꢊ (ꢉ ꢘꢈꢊ ꢁꢅꢇꢘ(ꢜꢄꢛꢞꢗ
ꢁꢞ$ꢊꢒ
ꢂꢉ'ꢊ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢈꢆ% ꢚꢊꢊꢉ ꢊꢉꢆꢚꢇꢊ$ ꢘꢈꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ ꢃꢊꢛ(ꢆꢇ
ꢄꢆꢘꢆ ꢝ(ꢇꢇ ꢚꢊ ꢗꢛꢞ'ꢊ%%ꢊ$ ꢆ% (ꢉ 7ꢞꢛꢙꢆꢇ ꢂꢗꢊꢛꢆꢘ(ꢞꢉꢒ ꢎꢈꢊ
ꢃꢎꢌꢍꢎ
ꢄꢞꢊ%
7ꢞ
7ꢊꢝꢇ& ꢍꢊ'ꢊ(ꢑꢊ$
ꢌ$$ꢛꢊ%% ꢙꢆꢘ'ꢈ
ꢀ,ꢋ ꢌ$$ꢛꢊ%%
T
ꢍꢊMꢊ'ꢘ ꢀꢈꢆꢛꢆ'ꢘꢊꢛ
ꢍꢊ'ꢊ(ꢑꢊꢛ (% ꢄ(%ꢆꢚꢇꢊ$
ꢍꢊ'ꢊ(ꢑꢊꢛ ꢛꢊꢙꢆ(ꢉ% ꢄ(%ꢆꢚꢇꢊ$
ꢀꢈꢆꢉꢉꢊꢇ (% ꢀꢞꢙꢙꢆꢉ$ꢊ$
(ꢉꢘꢞ ꢁꢅꢇꢘ(ꢜꢄꢛꢞꢗ ꢁꢞ$ꢊꢒ
ꢁꢍꢔꢉN<41O J Nꢔ" ꢔO
Gꢊ%
2ꢉꢆꢚꢇꢊ ꢍꢊ'ꢊ(ꢑꢊꢛ
ꢏBꢛ(ꢘꢊ !ꢓꢈ ꢘꢞ ꢘꢈꢊ
ꢌꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ ꢀꢈꢆꢉꢉꢊꢇ
ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛꢐ
8ꢆ%
ꢍ5ꢍꢄG #ꢉ$('ꢆꢘꢞꢛ
ꢚꢊꢊꢉ ꢆ%%ꢊꢛꢘꢊ$
T
7ꢞ
ꢍꢊꢆ$ (ꢉ ꢄꢆꢘꢆ ꢀꢈꢆꢛꢆ'ꢘꢊꢛ
+ꢛꢞꢙ ꢍ8ꢍꢒ
Gꢊ%
ꢀꢈꢊ'3 ꢃꢍꢉN6O
ꢍꢊꢆ$ (ꢉ ꢌ$$ꢛꢊ%%
ꢀꢈꢆꢛꢆ'ꢘꢊꢛ +ꢛꢞꢙ ꢍ8ꢍꢉ
#% ꢘꢈꢊ
7ꢊꢝ ꢀꢈꢆꢛꢆ'ꢘꢊꢛ ꢆ
ꢄꢆꢘꢆ ꢀꢈꢆꢛꢆ'ꢘꢊꢛ
ꢃꢍꢉN6O J ꢔT
Gꢊ%
7ꢞ
Figure 49. A Flow Diagram Depicting a Procedure That Can Be Used to Receive
Characters in the Multi-Drop Mode.
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
=/
XR88C681
H.3 Standby Mode
ꢁ ꢀꢆꢉꢉꢞꢘ ꢞꢗꢊꢛꢆꢘꢊ (ꢉ ꢘꢈꢊ ?ꢜꢁꢞ$ꢊ
ꢎꢈ(% (% $ꢅꢊ ꢘꢞ ꢇꢆ'3 ꢞ+ ꢘꢈꢊ ꢜ#ꢌꢀ:" #2#" ꢆꢉ$ #2ꢂ ꢗ(ꢉ%
ꢎꢈꢊ ꢄꢋꢌꢍꢎ ꢙꢆ& ꢚꢊ ꢗꢇꢆ'ꢊ$ (ꢉ ꢆ %ꢘꢆꢉ$ꢚ& ꢙꢞ$ꢊ ꢘꢞ
'ꢞꢉ%ꢊꢛꢑꢊ ꢗꢞꢝꢊꢛ ꢝꢈꢊꢉ (ꢘ% ꢞꢗꢊꢛꢆꢘ(ꢞꢉ (% ꢉꢞꢘ ꢛꢊEꢅ(ꢛꢊ$ꢒ ꢋꢗꢞꢉ
ꢛꢊ%ꢊꢘ" ꢘꢈꢊ ꢄꢋꢌꢍꢎ ꢝ(ꢇꢇ ꢚꢊ (ꢉ ꢘꢈꢊ Cꢌꢀꢎ#;2 ꢂ,2ꢍꢌꢎ#ꢂ7D
ꢙꢞ$ꢊꢒ ꢌ Cꢃ2ꢎ ꢃꢎꢌ7ꢄ*G ꢁꢂꢄ2D 'ꢞꢙꢙꢆꢉ$ (%%ꢅꢊ$ ꢑ(ꢆ
ꢘꢈꢊ 'ꢈꢆꢉꢉꢊꢇ ꢌ ꢀꢞꢙꢙꢆꢉ$ ꢍꢊ-(%ꢘꢊꢛ $(%ꢆꢚꢇꢊ% ꢆꢇꢇ 'ꢇꢞ'3% ꢞꢉ
ꢘꢈꢊ $ꢊꢑ('ꢊ ꢊ!'ꢊꢗꢘ +ꢞꢛ ꢘꢈꢊ 'ꢛ&%ꢘꢆꢇ ꢞ%'(ꢇꢇꢆꢘꢞꢛ" ꢝꢈ('ꢈ
%(-ꢉ(+('ꢆꢉꢘꢇ& ꢛꢊ$ꢅ'ꢊ% ꢘꢈꢊ ꢞꢗꢊꢛꢆꢘ(ꢉ- 'ꢅꢛꢛꢊꢉꢘꢒ #ꢉ ꢘꢈ(% ꢙꢞ$ꢊ
ꢘꢈꢆꢘ ꢞꢉꢇ& +ꢅꢉ'ꢘ(ꢞꢉ% ꢝꢈ('ꢈ ꢝ(ꢇꢇ ꢞꢗꢊꢛꢆꢘꢊ 'ꢞꢛꢛꢊ'ꢘꢇ& ꢆꢛꢊ ꢛꢊꢆ$(ꢉ-
ꢘꢈꢊ (ꢉꢗꢅꢘ ꢗꢞꢛꢘ" ꢝꢛ(ꢘ(ꢉ- ꢘꢈꢊ ꢞꢅꢘꢗꢅꢘ ꢗꢞꢛꢘ ꢆꢉ$ ꢘꢈꢊ Cꢃ2ꢎ
ꢌꢀꢎ#;2 ꢁꢂꢄ2D 'ꢞꢙꢙꢆꢉ$ꢒ ꢎꢈꢊ ꢇꢆꢘꢘꢊꢛ" ꢆꢇ%ꢞ (ꢉꢑꢞ3ꢊ$ ꢑ(ꢆ
ꢘꢈꢊ ꢀꢈꢆꢉꢉꢊꢇ ꢌ ꢀꢞꢙꢙꢆꢉ$ ꢛꢊ-(%ꢘꢊꢛ" ꢛꢊ%ꢘꢞꢛꢊ% ꢘꢈꢊ $ꢊꢑ('ꢊ ꢘꢞ
ꢉꢞꢛꢙꢆꢇ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ ꢝ(ꢘꢈ(ꢉ ꢓ6• %ꢒ ꢍꢊ%ꢊꢘꢘ(ꢉ- ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ%
ꢆꢉ$ ꢛꢊ'ꢊ(ꢑꢊꢛ% ꢆꢉ$ ꢝꢛ(ꢘ(ꢉ- ꢕꢕꢈ (ꢉꢘꢞ ꢘꢈꢊ #ꢁꢍ ꢏ#ꢉꢘꢊꢛꢛꢅꢗꢘ ꢁꢆ%3
ꢍꢊ-(%ꢘꢊꢛꢐ ꢚꢊ+ꢞꢛꢊ -ꢞ(ꢉ- (ꢉꢘꢞ ꢘꢈꢊ ꢃꢘꢆꢉ$ꢚ& ꢙꢞ$ꢊ (%
ꢛꢊ'ꢞꢙꢙꢊꢉ$ꢊ$ ꢘꢞ ꢗꢛꢊꢑꢊꢉꢘ ꢆꢉ& %ꢗꢅꢛ(ꢞꢅ% (ꢉꢘꢊꢛꢛꢅꢗꢘ% +ꢛꢞꢙ
ꢚꢊ(ꢉ- -ꢊꢉꢊꢛꢆꢘꢊ$ꢒ ꢎꢈꢊ 'ꢈ(ꢗ %ꢈꢞꢅꢇ$ ꢚꢊ ꢛꢊꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢆ+ꢘꢊꢛ
ꢘꢈꢊ Cꢃ2ꢎ ꢌꢀꢎ#;2 ꢁꢂꢄ2D 'ꢞꢙꢙꢆꢉ$ %(ꢉ'ꢊ ꢛꢊ-(%ꢘꢊꢛ
'ꢞꢉꢘꢊꢉꢘ% ꢆꢛꢊ ꢉꢞꢘ -ꢅꢆꢛꢆꢉꢘꢊꢊ$ ꢘꢞ ꢛꢊꢙꢆ(ꢉ %ꢘꢆꢚꢇꢊ $ꢅꢛ(ꢉ- ꢘꢈꢊ
%ꢘꢆꢉ$ꢚ& ꢙꢞ$ꢊꢒ ꢌ'ꢘ(ꢑꢊ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ 'ꢆꢉ ꢆꢇ%ꢞ ꢚꢊ ꢛꢊ%ꢘꢞꢛꢊ$ ꢑ(ꢆ
ꢈꢆꢛ$ꢝꢆꢛꢊ ꢛꢊ%ꢊꢘꢒ
ꢁ ꢀꢆꢉꢉꢞꢘ ꢗꢊꢛ+ꢞꢛꢙ ꢙꢞ$ꢊꢙ %ꢈꢆ3(ꢉ- +ꢅꢉ'ꢘ(ꢞꢉ%
ꢎꢈ(% (% $ꢅꢊ ꢘꢞ ꢘꢈꢊ ꢇꢆ'3 ꢞ+ ꢆꢉ& ꢀꢎꢃ ꢗ(ꢉ%
J. PROGRAMMING
ꢂꢗꢊꢛꢆꢘ(ꢞꢉ ꢞ+ ꢘꢈꢊ ꢄꢋꢌꢍꢎ (% ꢗꢛꢞ-ꢛꢆꢙꢙꢊ$ ꢚ& ꢝꢛ(ꢘ(ꢉ- 'ꢞꢉꢘꢛꢞꢇ
ꢝꢞꢛ$% (ꢉꢘꢞ ꢘꢈꢊ ꢆꢗꢗꢛꢞꢗꢛ(ꢆꢘꢊ ꢛꢊ-(%ꢘꢊꢛ%" ꢝꢈ(ꢇꢊ ꢞꢗꢊꢛꢆꢘ(ꢞꢉꢆꢇ
+ꢊꢊ$ꢚꢆ'3 (% ꢗꢛꢞꢑ($ꢊ$ ꢚ& %ꢘꢆꢘꢅ% ꢛꢊ-(%ꢘꢊꢛ% ꢝꢈ('ꢈ 'ꢆꢉ ꢚꢊ ꢛꢊꢆ$
ꢚ& ꢘꢈꢊ ꢀ,ꢋꢒ ꢍꢊ-(%ꢘꢊꢛ ꢆ$$ꢛꢊ%%(ꢉ- (% %ꢈꢞꢝꢉ (ꢉ ꢒ
ꢌ ꢈꢆꢛ$ꢝꢆꢛꢊ ꢛꢊ%ꢊꢘ 'ꢇꢊꢆꢛ% ꢘꢈꢊ 'ꢞꢉꢘꢊꢉꢘ% ꢞ+ ꢘꢈꢊ ꢃꢍꢉ" #ꢁꢍ"
#ꢃꢍ" ꢂ,ꢍ" ꢆꢉ$ ꢂ,ꢀꢍ ꢛꢊ-(%ꢘꢊꢛ% ꢆꢉ$ (ꢉ(ꢘ(ꢆꢇ(Iꢊ% ꢘꢈꢊ #;ꢍ ꢘꢞ
ꢕ ꢒ ꢄꢅꢛ(ꢉ- ꢞꢗꢊꢛꢆꢘ(ꢞꢉ" 'ꢆꢛꢊ %ꢈꢞꢅꢇ$ ꢚꢊ ꢊ!ꢊꢛ'(%ꢊ$ (+ ꢘꢈꢊ
ꢔ/
'ꢞꢉꢘꢊꢉꢘ% ꢞ+ 'ꢞꢉꢘꢛꢞꢇ ꢛꢊ-(%ꢘꢊꢛ% ꢆꢛꢊ ꢘꢞ ꢚꢊ 'ꢈꢆꢉ-ꢊ$" %(ꢉ'ꢊ
'ꢊꢛꢘꢆ(ꢉ 'ꢈꢆꢉ-ꢊ% ꢙꢆ& ꢛꢊ%ꢅꢇꢘ (ꢉ (ꢙꢗꢛꢞꢗꢊꢛ ꢞꢗꢊꢛꢆꢘ(ꢞꢉꢒ
ꢞꢛ 2!ꢆꢙꢗꢇꢊ4
ꢀꢈꢆꢉ-(ꢉ- ꢘꢈꢊ ꢉꢅꢙꢚꢊꢛ ꢞ+ ꢚ(ꢘ% ꢗꢊꢛ 'ꢈꢆꢛꢆ'ꢘꢊꢛ ꢝꢈ(ꢇꢊ $ꢆꢘꢆ (%
ꢚꢊ(ꢉ- ꢛꢊ'ꢊ(ꢑꢊ$ ꢙꢆ& ꢛꢊ%ꢅꢇꢘ (ꢉ ꢛꢊ'ꢊꢗꢘ(ꢞꢉ ꢞ+ ꢊꢛꢛꢞꢉꢊꢞꢅ%
'ꢈꢆꢛꢆ'ꢘꢊꢛꢒ #ꢉ -ꢊꢉꢊꢛꢆꢇ" 'ꢈꢆꢉ-ꢊ% ꢘꢞ ꢛꢊ-(%ꢘꢊꢛ% ꢝꢈ('ꢈ 'ꢞꢉꢘꢛꢞꢇ
ꢛꢊ'ꢊ(ꢑꢊꢛ ꢞꢛ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢞꢗꢊꢛꢆꢘ(ꢞꢉ %ꢈꢞꢅꢇ$ ꢚꢊ ꢙꢆ$ꢊ ꢞꢉꢇ&
ꢝꢈ(ꢇꢊ ꢘꢈꢊ ꢘꢛꢆꢉ%ꢙ(ꢘꢘꢊꢛ ꢞꢛ ꢛꢊ'ꢊ(ꢑꢊꢛ ꢆꢛꢊ $(%ꢆꢚꢇꢊ$" ꢆꢉ$ 'ꢊꢛꢘꢆ(ꢉ
'ꢈꢆꢉ-ꢊ% ꢘꢞ ꢘꢈꢊ ꢌꢀꢍ %ꢈꢞꢅꢇ$ ꢚꢊ ꢙꢆ$ꢊ ꢞꢉꢇ& ꢝꢈꢊꢉ ꢘꢈꢊ ꢀ.ꢎ (%
%ꢘꢞꢗꢗꢊ$ꢒ
I. COMMENTS ABOUT THE XR88C681 IN 28 PIN
DIP PACKAGE
ꢁꢅ'ꢈ ꢞ+ ꢘꢈ(% $ꢆꢘꢆ %ꢈꢊꢊꢘ $(%'ꢅ%%ꢊ$ +ꢊꢆꢘꢅꢛꢊ% ꢝꢈ('ꢈ ꢆꢛꢊ
ꢆꢑꢆ(ꢇꢆꢚꢇꢊ ꢘꢞ ꢘꢈꢊ ꢄꢋꢌꢍꢎ% ꢝꢈ('ꢈ ꢆꢛꢊ ꢗꢆ'3ꢆ-ꢊ$ (ꢉ ꢘꢈꢊ <ꢕ ꢗ(ꢉ
ꢄ#, ꢞꢛ ꢘꢈꢊ << ꢗ(ꢉ ,9ꢀꢀꢒ 8ꢞꢝꢊꢑꢊꢛ" ꢚꢊ'ꢆꢅ%ꢊ ꢞ+ ꢘꢈꢊ
ꢛꢊ$ꢅ'ꢊ$ ꢉꢅꢙꢚꢊꢛ ꢞ+ ꢗ(ꢉ% ꢘꢈꢊ ꢄꢋꢌꢍꢎ% (ꢉ ꢘꢈꢊ ꢓ= ꢗ(ꢉ
ꢗꢆ'3ꢆ-ꢊ $ꢞ ꢉꢞꢘ ꢈꢆꢑꢊ ꢘꢈꢊ +ꢞꢇꢇꢞꢝ(ꢉ- +ꢊꢆꢘꢅꢛꢊ%ꢒ
ꢁꢞ$ꢊ" 'ꢞꢙꢙꢆꢉ$" 'ꢇꢞ'3 %ꢊꢇꢊ'ꢘ" ꢆꢉ$ %ꢘꢆꢘꢅ% ꢛꢊ-(%ꢘꢊꢛ% ꢆꢛꢊ
$ꢅꢗꢇ('ꢆꢘꢊ$ +ꢞꢛ ꢊꢆ'ꢈ 'ꢈꢆꢉꢉꢊꢇ ꢘꢞ ꢗꢛꢞꢑ($ꢊ ꢘꢞꢘꢆꢇ (ꢉ$ꢊꢗꢊꢉ$ꢊꢉꢘ
ꢞꢗꢊꢛꢆꢘ(ꢞꢉꢒ Table 29 ꢘꢈꢛꢞꢅ-ꢈ Table 41 %ꢅꢙꢙꢆꢛ(Iꢊ% ꢘꢈꢊ ꢚ(ꢘ
ꢆ%%(-ꢉꢙꢊꢉꢘ% +ꢞꢛ ꢊꢆ'ꢈ ꢛꢊ-(%ꢘꢊꢛꢒ
REGISTER SUMMARY
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Rx RTS
Control
Rx Int Select Error Mode
Parity Mode
Select
Parity
Select
Number of Bits/Char.
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕJꢍ5ꢍꢄG
ꢔJ ꢋ99
ꢕJ ꢀꢈꢆꢛꢒ
ꢔJ *ꢇꢞ'3
ꢕꢕ J B(ꢘꢈ ,ꢆꢛ(ꢘ&
ꢕ J 2ꢑꢊꢉ
ꢔ J ꢂ$$
ꢕꢕ J 6
ꢕꢔ J /
ꢔꢕ J >
ꢔꢔ J =
ꢕꢔ J ꢞꢛ'ꢊ ,ꢆꢛ(ꢘ&
ꢔꢕ J 7ꢞ ,ꢆꢛ(ꢘ&
ꢔꢔ J ꢁꢅꢇꢘ(ꢜꢄꢛꢞꢗ ꢁꢞ$ꢊ
Table 29. Mode Registers 1: MR1A, MR1B
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
=>
XR88C681
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Channel Mode
Tx RTS
Control
CTS Enable
Tx
Stop Bit Length
ꢕꢕ J 7ꢞꢛꢙꢆꢇ
ꢕꢔ J ꢌꢅꢘꢞ 2'ꢈꢞ
ꢔꢕ J 9ꢞ'ꢆꢇ 9ꢞꢞꢗ
ꢔꢔ J ꢍꢊꢙꢞꢘꢊ 9ꢞꢞꢗ
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕꢈ J ꢕꢒ6/1
ꢔꢈ J ꢕꢒ/ꢓ6
ꢓꢈ J ꢕꢒ/==
1ꢈ J ꢕꢒ>6ꢕ
<ꢈ J ꢕꢒ=ꢔ1
6ꢈ J ꢕꢒ=>6
/ꢈ J ꢕꢒꢖ1=
>ꢈ J ꢔꢒꢕꢕꢕ
=ꢈ J ꢔꢒ6/1
ꢖꢈ J ꢔꢒ/ꢓ6
ꢌꢈ J ꢔꢒ/==
*ꢈ J ꢔꢒ>6ꢕ
ꢀꢈ J ꢔꢒ=ꢔ1
ꢄꢈ J ꢔꢒ=>6
2ꢈ J ꢔꢒꢖ1=
ꢈ J ꢓꢒꢕꢕꢕ
Table 30. Mode Register 2: MR2A, MR2B
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Receiver Clock Select
Transmitter Clock Select
ꢃꢊꢊ Table 9
ꢃꢊꢊ Table 9
Table 31. Clock Select Registers: CSRA, CSRB
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Miscellaneous Commands
Enable/Disable Tx
Enable/Disable Rx
ꢃꢊꢊ ꢎꢊ!ꢘ (ꢉ Section B.2ꢒ
ꢕꢕ J 7ꢞ ꢀꢈꢆꢉ-ꢊ
ꢕꢔ J 2ꢉꢆꢚꢇꢊ ꢎ!
ꢔꢕ J ꢄ(%ꢆꢚꢇꢊ ꢎ!
ꢔꢔ J 7ꢞꢘ ꢌꢇꢇꢞꢝꢊ$
ꢏꢄꢞ 7ꢞꢘ ꢋ%ꢊꢐ
ꢕꢕ J 7ꢞ ꢀꢈꢆꢉ-ꢊ
ꢕꢔ J 2ꢉꢆꢚꢇꢊ ꢎ!
ꢔꢕ J ꢄ(%ꢆꢚꢇꢊ ꢎ!
ꢔꢔ J 7ꢞꢘ ꢌꢇꢇꢞꢝꢊ$
ꢏꢄꢞ 7ꢞꢘ ꢋ%ꢊꢐ
Table 32. Command Registers: CRA, CRB
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Received
Break
Framing
Error
Parity Error
Overrun
Error
TXEMT
TXRDY
FFULL
RXRDY
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
Table 33. Status Registers: SRA, SRB
Bit 7
OP7
Bit 6
OP6
Bit 5
OP5
Bit 4
OP4
Bit 3
Bit 2
Bit 1
Bit 0
OP3
OP2
ꢕJꢂ,ꢍN>O
ꢔJꢎ5ꢍꢄG*
ꢕJꢂ,ꢍN/O
ꢔJꢎ5ꢍꢄGꢌ
ꢕJꢂ,ꢍN6O
ꢔJꢍ5ꢍꢄG.
ꢋ99*
ꢕJꢂ,ꢍN<O
ꢔJꢍ5ꢍꢄG.
ꢋ99ꢌ
ꢕꢕ J ꢂ,ꢍN1O
ꢕꢔ J ꢀ.ꢎ Sꢔ ꢂꢅꢘꢗꢅꢘ
ꢔꢕ J ꢎ5ꢀ* ꢏꢔ5ꢐ
ꢔꢔ J ꢍ5ꢀ* ꢏꢔ5ꢐ
ꢕꢕ J ꢂ,ꢍNꢓO
ꢕꢔ J ꢎ5ꢀꢌ ꢏꢔ/5ꢐ
ꢔꢕ J ꢎ5ꢀꢌ ꢏꢔ5ꢐ
ꢔꢔ J ꢍ5ꢀꢌ ꢏꢔ5ꢐ
Table 34. Output Port Configuration Register: OPCR
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
==
XR88C681
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
BRG Set
Select
Counter/Timer #1 Mode and Source
Delta IP3
Interrupt
Delta IP2
Interrupt
Delta IP1
Interrupt
Delta IP0
Interrupt
ꢕ J ꢃꢊꢘꢔ
ꢔ J ꢃꢊꢘꢓ
ꢃꢊꢊ Table 7
ꢕ J ꢂ
ꢔ J ꢂ7
ꢕ J ꢂ
ꢔ J ꢂ7
ꢕ J ꢂ
ꢔ J ꢂ7
ꢕ J ꢂ
ꢔ J ꢂ7
Table 35. Auxiliary Control Register: ACR
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
IP3
Bit 2
IP2
Bit 1
IP1
Bit 0
IP0
Delta IP3
Delta IP2
Delta IP1
Delta IP0
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 9ꢞꢝ
ꢔ J 8(-ꢈ
ꢕ J 9ꢞꢝ
ꢔ J 8(-ꢈ
ꢕ J 9ꢞꢝ
ꢔ J 8(-ꢈ
ꢕ J 9ꢞꢝ
ꢔ J 8(-ꢈ
Table 36. Input Port Configuration Register , IPCR
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Input Port
Change
Delta Break
B
RXRDY/
FFULLB
TXRDYB
Counter #1
Ready
Delta Break
A
RXRDY/
FFULLA
TXRDYA
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
ꢕ J 7ꢞ
ꢔ J Gꢊ%
Table 37. Interrupt Status Register, ISR
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Input Port
Change
Delta Break
B
RXRDY/
FFULLB
TXRDYB
Counter #1
Ready
Delta Break
A
RXRDY/
FFULLA
TXRDYA
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
ꢕ J ꢂ++
ꢔ J ꢂꢉ
Table 38. Interrupt Mask Register, IMR
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
ꢀ.ꢎꢏꢔ6ꢐ
ꢀ.ꢎꢏꢔ<ꢐ
ꢀ.ꢎꢏꢔ1ꢐ
ꢀ.ꢎꢏꢔꢓꢐ
ꢀ.ꢎꢏꢔꢔꢐ
ꢀ.ꢎꢏꢔꢕꢐ
ꢀ.ꢎꢏꢖꢐ
ꢀ.ꢎꢏ=ꢐ
Table 39. Counter/Timer Upper Byte Register, CTUR
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
ꢀ.ꢎꢏ>ꢐ
ꢀ.ꢎꢏ/ꢐ
ꢀ.ꢎꢏ6ꢐ
ꢀ.ꢎꢏ<ꢐ
ꢀ.ꢎꢏ1ꢐ
ꢀ.ꢎꢏꢓꢐ
ꢀ.ꢎꢏꢔꢐ
ꢀ.ꢎꢏꢕꢐ
Table 40. Counter/Timer Lower Byte Register, CTLR
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
#;ꢍꢏ>ꢐ
#;ꢍꢏ/ꢐ
#;ꢍꢏ6ꢐ
#;ꢍꢏ<ꢐ
#;ꢍꢏ1ꢐ
#;ꢍꢏꢓꢐ
#;ꢍꢏꢔꢐ
#;ꢍꢏꢕꢐ
Table 41. Interrupt Vector Register: IVR
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
=ꢖ
XR88C681
K. TIMING DIAGRAMS
ꢓꢒꢕ;
ꢕꢒ=;
ꢓꢒꢕ;
ꢕꢒ=;
<ꢒꢕ;
ꢎꢊ%ꢘ 9ꢊꢑꢊꢇ%
Figure 50. Input and Output Levels for Timing Measurements
Note: AC testing inputs are driven at 0.4V for a logic “0” and 2.4V for a logic “1” except for -40 to 85(C and -55 to 125(C, logic “1” shall
be 2.6V. Timing measurements are made at 0.8V for a logic “0” and 2.0V for a logic “1”.
ꢍ2ꢃ2ꢎ
ꢘ
ꢍ2ꢃ
Figure 51. Reset Timing
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢖꢕ
XR88C681
ꢌꢕ ꢜ ꢌ1
ꢘ
ꢘ
ꢌꢃ
ꢌ8
ꢜꢀꢃ
ꢜꢍꢄ
ꢘ
ꢀ8
ꢘ
ꢀꢃ
ꢘ
ꢍBꢄ
ꢘ
ꢍB
ꢘ
ꢘ
ꢄ
ꢄꢄ
ꢄꢕ ꢜ ꢄ>
ꢏꢍꢊꢆ$ꢐ
7ꢂꢎ
;ꢌ9#ꢄ
9ꢂꢌꢎ
;ꢌ9#ꢄ
9ꢂꢌꢎ
ꢘ
ꢍBꢄ
ꢜBꢍ
ꢘ
ꢄꢃ
ꢘ
ꢄ8
ꢄꢕ ꢜ ꢄ>
ꢏBꢛ(ꢘꢊꢐ
;ꢌ9#ꢄ
Figure 52. XR88C681 Read and Write Cycle Timing
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢖꢔ
XR88C681
ꢜ#7ꢎꢍ
ꢜ#ꢌꢀ:
ꢘ
#ꢌ8
ꢘ
#ꢌꢃ
ꢘ
ꢍB
ꢜꢍꢄ
ꢘ
2#ꢃ
ꢘ
ꢘ
ꢄ
ꢄꢄ
ꢄꢕ ꢜ ꢄ>
7ꢂꢎ
;ꢌ9#ꢄ
9ꢂꢌꢎ
;2ꢀꢎꢂꢍ
9ꢂꢌꢎ
#2#
ꢘ
ꢘ
ꢄ#ꢂ
2ꢂꢄ
#2ꢂ
ꢘ
ꢄ#ꢂ
ꢍ2ꢃ2ꢎ #ꢋꢃ
ꢀꢂꢁꢁꢌ7ꢄ
Figure 53. XR88C681 Z Mode Interrupt Cycle Timing
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢖꢓ
XR88C681
ꢜꢍꢄ ꢞꢛ
ꢜꢀꢃ
ꢘ
ꢘ
,8
,ꢃ
#,ꢕ ꢜ #,/
ꢜBꢍ ꢞꢛ
ꢜꢀꢃ
ꢂ,ꢕ ꢜ ꢂ,>
72B ꢄꢌꢎꢌ
ꢂ9ꢄ ꢄꢌꢎꢌ
ꢘ
,ꢄ
Figure 54. Port Timing
ꢜꢍꢄ ꢞꢛ
ꢜꢀꢃ ꢞꢛ
ꢜBꢍ
ꢘ
#ꢍ
#ꢉꢘꢊꢛꢛꢅꢗꢘ
ꢂꢅꢘꢗꢅꢘ
Figure 55. Interrupt Timing
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢖ1
XR88C681
ꢀꢔ4 ꢔꢕꢗ A ꢏꢃꢘꢛꢆ& Q 6ꢗ ꢐ
ꢀꢓ4 ꢔꢕꢗ A ꢏꢃꢘꢛꢆ& Q 6ꢗ ꢐ
ꢍꢔ4 ꢔꢕꢕꢞꢈꢙ
ꢀꢔ4 ꢔꢕ ꢜ ꢔ6ꢗ A ꢏꢃꢘꢛꢆ& Q 6ꢗ ꢐ
ꢀꢓ4 ꢕ ꢜ 6ꢗ A ꢏꢃꢘꢛꢆ& Q 6ꢗ ꢐ
ꢍꢓ4 ꢔꢕꢕꢞꢈꢙ
ꢍꢔ
5ꢔ
5ꢔ
ꢀꢔ
ꢀꢓ
ꢀꢔ
ꢀꢓ
XR88C681
XR88C681
ꢍꢓ
5ꢓ
5ꢓ
1ꢒ/=/<ꢁ8I
1ꢒ/=/<ꢁ8I
,ꢆꢛꢆꢇꢇꢊꢇ ꢍꢊ%ꢞꢉꢆꢉꢘ ꢀꢛ&%ꢘꢆꢇ
,ꢆꢛꢆꢇꢇꢊꢇ ꢍꢊ%ꢞꢉꢆꢉꢘ ꢀꢛ&%ꢘꢆꢇ
ꢘ
ꢘ
ꢀ9:
ꢀꢎꢀ
5ꢔ.ꢀ9:
ꢀ.ꢎ ꢀ9:
ꢍ5ꢀ
ꢘ
ꢍꢎ5
ꢎ5ꢀ
ꢘ
ꢘ
ꢀ9:
ꢀꢎꢀ
ꢘ
ꢍꢎ5
Figure 56. Clock Timing
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢖ<
XR88C681
ꢔ *(ꢘ ꢎ(ꢙꢊ
ꢏꢔ ꢞꢛ ꢔ/ ꢀꢇꢞ'3%ꢐ
ꢎ5ꢀ
ꢏ#ꢉꢗꢅꢘꢐ
ꢘ
ꢎ5ꢄ
ꢎ5ꢄ
ꢘ
ꢎꢀꢃ
ꢎ5ꢀ
ꢏꢔ5 ꢂꢅꢘꢗꢅꢘꢐ
Figure 57. Transmitter Timing
ꢍ5ꢀ
ꢔ5 #ꢉꢗꢅꢘꢐ
ꢘ
ꢘ
ꢍ58
ꢍ5ꢃ
ꢍ5ꢄ
Figure 58. Receiver Timing
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢖ6
XR88C681
44 LEAD PLASTIC LEADED CHIP CARRIER
(PLCC)
Rev. 1.00
C
D
ꢃꢊꢆꢘ(ꢉ- ,ꢇꢆꢉꢊ
D
ꢔ
45ꢀ x H1
A
2
45ꢀ x H2
ꢓ
ꢔ <<
B
1
B
D
D
1
D
2
D
3
e
R
D
3
A
1
A
INCHES
MIN MAX
MILLIMETERS
SYMBOL
MIN
MAX
ꢌ
ꢕꢒꢔ/6
ꢕꢒꢕꢖꢕ
ꢕꢒꢕꢓꢕ
ꢕꢒꢕꢔ1
ꢕꢒꢕꢓ/
ꢕꢒꢕꢕ=
ꢕꢒ/=6
ꢕꢒ/6ꢕ
ꢕꢒ6ꢖꢕ
ꢕꢒꢔ=ꢕ
ꢕꢒꢔꢓꢕ
UUUꢒ
<ꢒꢔꢖ
ꢓꢒꢓꢖ
<ꢒ6>
1ꢒꢕ6
ꢌ
ꢌ
*
*
ꢔ
ꢓ
ꢕꢒ6ꢔ
UUU
ꢕꢒꢕꢓꢔ
ꢕꢒꢕ1ꢓ
ꢕꢒꢕꢔ1
ꢕꢒ/ꢖ6
ꢕꢒ/6/
ꢕꢒ/1ꢕ
ꢕꢒ11
ꢕꢒ61
ꢕꢒ//
ꢕꢒ=ꢔ
ꢔ
ꢀ
ꢄ
ꢄ
ꢄ
ꢄ
ꢊ
ꢕꢒꢔꢖ
ꢕꢒ1ꢓ
ꢔ>ꢒ<ꢕ
ꢔ/ꢒ6ꢔ
ꢔ<ꢒꢖꢖ
ꢔ>ꢒ/6
ꢔ/ꢒ//
ꢔ/ꢒꢕꢕ
ꢔ
ꢓ
1
ꢕꢒ6ꢕꢕ ꢘ&ꢗꢒ
ꢕꢒꢕ6ꢕ *ꢃꢀ
ꢔꢓꢒ>ꢕ ꢘ&ꢗꢒ
ꢔꢒꢓ> *ꢃꢀ
8ꢔ
8ꢓ
ꢍ
ꢕꢒꢕ<ꢓ
ꢕꢒꢕ6/
ꢕꢒꢕ<=
ꢕꢒꢕ<6
ꢔꢒꢕ>
ꢔꢒ<ꢓ
ꢔꢒꢓꢓ
ꢔꢒꢔ<
ꢕꢒꢕ<ꢓ
ꢕꢒꢕꢓ6
ꢔꢒꢕ>
ꢕꢒ/<
Note: The control dimension is the inch column
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢖ/
XR88C681
40 LEAD CERAMIC DUAL-IN-LINE
(600 MIL CDIP)
Rev. 1.00
<ꢕ
ꢓꢔ
ꢔ
ꢓꢕ
E
E
1
D
A
1
Base
A
Plane
Seating
Plane
L
c
e
ꢁ
B
B
1
INCHES
MILLIMETERS
SYMBOL
MIN
MAX
MIN
MAX
ꢌ
ꢕꢒꢔꢕꢕ
ꢕꢒꢕꢔ6
ꢕꢒꢕꢔ<
ꢕꢒꢕ<6
ꢕꢒꢕꢕ=
ꢔꢒꢖꢖꢕ
ꢕꢒ66ꢕ
ꢕꢒꢓꢓ6
ꢕꢒꢕ>6
ꢕꢒꢕꢓ/
ꢕꢒꢕ/6
ꢕꢒꢕꢔ=
ꢓꢒꢕꢖꢕ
ꢕꢒ/ꢔꢕ
ꢓꢒ6<
ꢕꢒ1=
6ꢒ>ꢓ
ꢔꢒꢖꢔ
ꢌ
*
*
'
ꢔ
ꢕꢒ1/
ꢕꢒ//
ꢔꢒꢔ<
ꢔꢒ/6
ꢔ
ꢕꢒꢓꢕ
ꢕꢒ</
ꢄ
6ꢕꢒ66
ꢔ1ꢒꢖ>
61ꢒꢕꢖ
ꢔ6ꢒ<ꢖ
2
2
ꢊ
ꢔ
ꢕꢒ/ꢕꢕ *ꢃꢀ
ꢕꢒꢔꢕꢕ *ꢃꢀ
ꢔ6ꢒꢓ< *ꢃꢀ
ꢓꢒ6< *ꢃꢀ
9
ꢕꢒꢔꢓ6
ꢕꢀ
ꢕꢒꢓꢕꢕ
1ꢒꢔ=
ꢕꢀ
6ꢒꢕ=
ꢁ
ꢔ6ꢀ
ꢔ6ꢀ
Note: The control dimension is the inch column
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢖ>
XR88C681
40 LEAD PLASTIC DUAL-IN-LINE
(600 MIL PDIP)
Rev. 1.00
<ꢕ
ꢔ
ꢓꢔ
E
1
ꢓꢕ
E
D
A
A
2
A
L
Seating
Plane
1
C
ꢁ
B
B
1
e
e
e
A
B
INCHES
MILLIMETERS
SYMBOL
MIN
MAX
MIN
MAX
ꢌ
ꢕꢒꢔ/ꢕ
ꢕꢒꢕꢔ6
ꢕꢒꢔꢓ6
ꢕꢒꢕꢔ<
ꢕꢒꢕ1ꢕ
ꢕꢒꢕꢕ=
ꢔꢒꢖ=ꢕ
ꢕꢒ/ꢕꢕ
ꢕꢒ<=6
ꢕꢒꢓ6ꢕ
ꢕꢒꢕ>ꢕ
ꢕꢒꢔꢖ6
ꢕꢒꢕꢓ<
ꢕꢒꢕ>ꢕ
ꢕꢒꢕꢔ<
ꢓꢒꢕꢖ6
ꢕꢒ/ꢓ6
ꢕꢒ6=ꢕ
<ꢒꢕ/
ꢕꢒ1=
/ꢒ16
ꢔꢒ>=
ꢌ
ꢌ
*
*
ꢔ
ꢓ
1ꢒꢔ=
<ꢒꢖ6
ꢕꢒ1/
ꢕꢒ6/
ꢕꢒ>/
ꢔꢒ>=
ꢔ
ꢀ
ꢄ
2
ꢕꢒꢓꢕ
ꢕꢒ1=
6ꢕꢒꢓꢖ
ꢔ6ꢒꢓ<
ꢔꢓꢒ1ꢓ
61ꢒꢓꢔ
ꢔ6ꢒ==
ꢔ<ꢒ>1
2
ꢊ
ꢔ
ꢕꢒꢔꢕꢕ *ꢃꢀ
ꢕꢒ/ꢕꢕ *ꢃꢀ
ꢓꢒ6< *ꢃꢀ
ꢔ6ꢒꢓ< *ꢃꢀ
ꢊ
ꢌ
ꢊ
*
9
ꢕꢒ/ꢕꢕ
ꢕꢒ>ꢕꢕ
ꢕꢒꢓꢕꢕ
ꢔ6ꢒꢓ<
ꢔ>ꢒ>=
6ꢒꢕ=
ꢕꢒꢔꢔ6
ꢓꢒꢖꢓ
ꢁ
ꢕꢀ
ꢔ6ꢀ
ꢕꢀ
ꢔ6ꢀ
Note: The control dimension is the inch column
ꢍꢊꢑꢒ ꢓꢒꢔꢕ
ꢖ=
XR88C681
7ꢂꢎ#ꢀ2
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ꢀꢞꢗ&ꢛ(-ꢈꢘ ꢔꢖꢖꢖ 25ꢌꢍ ꢀꢞꢛꢗꢞꢛꢆꢘ(ꢞꢉ
ꢄꢆꢘꢆ%ꢈꢊꢊꢘ ꢃꢊꢗꢘꢊꢙꢚꢊꢛ ꢔꢖꢖꢖ
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ꢍꢊꢑꢒ ꢓꢒꢔꢕ
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相关型号：
XR88C681CJ-F
Serial I/O Controller, 2 Channel(s), 0.125MBps, CMOS, PQCC44, ROHS COMPLIANT, PLASTIC, LCC-44
EXAR
XR88C681CJTR-F
Serial I/O Controller, 2 Channel(s), 0.125MBps, CMOS, PQCC44, ROHS COMPLIANT, PLASTIC, LCC-44
EXAR
XR88C681CP/28-F
Serial I/O Controller, 2 Channel(s), 0.125MBps, CMOS, PDIP28, 0.600 INCH, GREEN, PLASTIC, DIP-28
EXAR
XR88C681CP/40-F
Serial I/O Controller, 2 Channel(s), 0.125MBps, CMOS, PDIP40, 0.600 INCH, ROHS COMPLIANT, PLASTIC, DIP-40
EXAR
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