CH1787 [ETC]
Telecommunication IC ; 电信IC\n
| 型号： | CH1787 |
| 厂家： | 
ETC |
| 描述： | Telecommunication IC
|
| 文件： | 总13页 (文件大小：1260K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
CH1787 Small Functional Modem
Cermetek
microelectronics
INTRODUCTION
FEATURES
The CH1787 is a small full function modem that is FCC Part
68 approved. It has been designed to be used in
applications where there is little or no controller intelligence
to command the modem. This allows the user to operate
the modem via hardware resources only, not requiring AT
Command execution for basic operation. For those
applications where there is controller intelligence, the
CH1787 operates like a standard AT Command driver
2400bps, V.22bis asychronous modem.
Supports Standards CCITT V.22bis, V.22,
Bell 212, and Bell 103
FCC Part 68 approved and DOC approvable
Does not require a microprocessor to operate
Pin activated hang-up
Pin activated answer
Manual originate and answer pins
AT Command structure available
1000 VAC isolation barrier
The CH1787 is ideal as a remote modem such as found in
alarm products and in industrial controllers. Upon some
operational event, the modem will dial a prestored telephone
number under pin activation to make a modem connection
with a host or another site. The modem can also be set to
automatically answer incoming calls or manually answer a
call, using an answering pin. A call can be ended via a
Single 5 volt operation
Low power sleep mode
Automatic adaptive and fixed compromise
equalization
Test modes and diagnostics
Size: 2.0 x 1.25 x 0.53
hang-up pin.
NVRAM allows storage of custom configurations
and telephone numbers
GENERAL DESCRIPTION OF FUNCTIONAL
BLOCKS
Figure 1 is a functional block diagram of the CH1787. Each
block will be described. The CH1787 is a highly integrated,
full function modem, comprised of a modulator/demodula-
tor, controller, and an FCC Part 68 approved telephone in-
terface, also called a Data Access Arrangement (DAA) and
NVRAM.
Operating temperature 0o-70oC
Extended temperature -40oC to 85oC order
CH1787ET
Modulation/Demodulation and Control
This Functional Block is comprised of a monolithic modem
integrated circuit, with built-in facilities to accommodate in-
tegrated AT command control and resident interfaces for
general communication and routing to the DAA.
Controller
The controller is a programed microprocessor that provides
commands to the modem in response to external pin acti-
vation. The following pins are controlled by the micropro-
cessor and are described in detail in Table 1. These pins
are operational when the modem is in use at 2400bps only.
ANS - Manual Answer Pin Input - Answer mode-
Places modem in answer mode
ORG - Manual Originate Pin Input - Originate mode -
places modem in originate mode
ORA- Automatic Dial Pin Input - Dials one of two
prestored numbers based on TST
TST - Steering Pin Input used with ORA to select the user
stored number or Cermetek test number
HNG- Hang-up Pin Input used to terminate an active
modem connected
Figure 1. CH1787 Functional Block Diagram
AAR- Automatic Answer Pin - used to place the modem
in Auto Answer Mode
See pin description Table 1 for more details.
Cermetek Microelectronics, Inc.
Document No. 603-0182 Rev. D (11/98)
1
DAA
The CH1787 is designed to meet North American telephone stan-
dards as set by FCC Part 68 and DOC. The telephone line inter-
face is designed to meet 1000VAC and 1500 volt peak surge
isolation, among other parameters. As such, it will meet U.S. and
Canadian requirements and other international requirements that
specify that level of isolation. The CH1787 comes with FCC Part
68 approval, a label is provided with the registration number and
ringer equivalent. This label should be prominently displayed.
As with most countries, except the U.S., Canada requires sub-
mission of the product containing the CH1787 for DOC approval.
This can be done by submitting the design to a test house or
consultant. Call Cermetek for a consultant list.
NVRAM
NVRAM can save up to two user-customized modem configura-
tions. The AT&Wn command will store the active modem con-
figuration in one of two NVRAM locations as selected by an n of 0
or 1. The AT&Yn command selects one of the stored modem
configurations to be automatically recalled and active upon a re-
set or power up. The ATZn command immediately recalls and
activates a stored configuration. See Tables 2 and 3 for storable
S-Registers and Commands.
Figure 2. Voice/Data Port Control
SLEEP MODE
To minimize the modem power consumption, the CH1787 includes
a power down feature called the Sleep Mode. When activated the
CH1787 will automatically enter the Sleep Mode after 0 to 255
seconds of inactivity. The time of inactivity is selected by the ATS24
command and 5 seconds is the default time. The modem returns
to normal operation when a ring signal is received or is upon an
input low signal on TXD. ATS24 = 255 disables the Sleep Mode
and is the default.
NVRAM can save up to four telephone numbers with up to 36
digits or modifiers in each telephone number. The AT&Zn=s com-
mand will store s, the telephone number dial string. The ATDTS=n
command will cause the modem to dial one of the four stored
telephone numbers. The NVRAM storage location for the four
telephone numbers is selected by an n of 0, 1, 2, or 3. Location 1
is used for the ORA stored number and Cermetek number.
_____
Supported Features
AT Command Set
A SLEEP output signal is available to control power to external
devices. In Figure 5, a FET controlled by the SLEEP signal turns off
the external speaker amplifier when the modem enters the Sleep
Mode. In the sleep mode, power is reduced by 50% of normal
operating power.
A 40-character command line is supported. The command line
starts with AT and may contain standard or enhanced commands.
See
Cermetek
detailed
command
summary-
www.cermetek.com.
Serial Host Interface
The serial interface is V.24 (EIA-232-D) compatible interface. See
pin description.
Transmission Speed
The transmission rate of the host computer must be 300, 1200, or
2400 bps. The modem will connect at the selected speed or will
fall back to the speed set by the remote or answering modems
serial interface (the DTE transmission speed). That determines
the originate speed. The modem can be either originating (calling
modem) or answering (remote modem). The following table
shows the speeds:
Speaker Interface
The SPK output reflects the receiver analog input and provides a
signal that can be used to monitor call progress. The SPK signal
can drive a 300 Ω load directly. The SPK signal is usually input to
an audio power amplifier and the amplifier drives a speaker coil.
Figure 5 shows how to drive an 8 Ω speaker.
Originate Mode
Answer Mode
300
1200
300
300
300
300
1200
1200
1200
1200
2400*
1200
1200
2400
The speaker can be turned on and off with the ATMn command.
The speaker volume can be adjusted by the ATLn command,
where n is 0, 1, 2, or 3.
2400
*Pin activated operation at 2400bps only. Other speeds may be
used with AT Command operation.
Phone Control
The CH1787 contains a pin called Voice/Data (V/D). This pin
toggles high when the modem goes off hook and can be used to
activate a relay which can switch a telephone on or off the Tip and
Ring Telco lines. This allows the telephone to be disconnected
when a data call is in progress, preventing the data from being
disturbed by an inadvertent telephone pick-up. See Figure 2.
Speed and Parity Selection
Before a call, the modem adjusts to the host speed (2400, 1200, or
300 bps) and parity (odd, even, mark, space, or none) via a host-
initiated training sequence. This also selects the speed of the
data for originate calls. The modem automatically adapts to the
callers speed on answer calls.
The modem matches the hosts parity when it returns status mes-
sages to the host. During a data connection, however, the modem
passes parity through without interpretation or alteration.
Cermetek Microelectronics, Inc.
Document No. 603-0182 Rev. D (11/98)
2
POWER SUPPLY
MECHANICAL RELAY ONLY.
ZERO IMPEDANCE SWITCH MAY REPLACE
THE RELAY AND TRANSISTOR CIRCUIT.
A
The modem module is a complex sub-system that may be treated
as any other component. Special attention should be paid to the
power supply connections. The modem decodes analog signals
from the telephone line that are in the millivolt range. Al though the
modem is designed to withstand significantly induced power sup-
ply noise, there is a limit. Steps must be taken to guarantee that
power supply noise on all supply lines, including ground, does not
exceed 50 mV peak to peak. Any frequency between 20 kHz and
150 kHz must be less than 50 mV peak. If necessary, use dedi-
cated power and ground planes. Failure to provide such operating
conditions could cause the modem to malfunction.
ENABLE RXA
4.7K
+5V
2N2222
1N914
+15V
1
2
RING
TIP
20K
CH1787
34
33
32
3
AAR
GND
VCC
B
4
A
499
1
+
20K
7
2
RXA
DTR
-
8
9
31
30
29
RXD
HNG
CON
TL064
2.2uF
nonpolar
ANS
0.1uF
0.1uF
10 V/D
RST
82K
0.1uF
11
28
27
26
20K
TST
SPKR
NC
12RI
13CTS
63.4K
14
15
16
NC 25
DSR
DRA
TXD
24
23
22
NC
DAG
HS
VOICE OR DTMF
SIGNAL
20K
17DIR
A1
54K
DCD 21
GND 20
18IRQ
19SLEEP
6
5
The CH1787requires a single +5V ±5% supply. It is recommended
that by-pass capacitors be placed on the power supply as close to
the modems supply input as practical. It is recommended that a
10 µF Electrolytic capacitor in parallel with a 0.01µF ceramic
capacitor be used.
-
+
7
0.1uF
11
28K
A2
TL064
0.1uF
WARNING: The CH1787 has been FCC Part 68 approved as a
data modem. Utilization of the Voice/Tone Port requires further
registration. FCC will require that the system, including the CH1787
and the handset or DTMF transceiver, adhere to Part 68 rules.
ADJUST A2 FOR THE DESIRED LEVEL OF AXT VOICE TO BE ECHOED TO AXR.
DECREASE RECEIVE GAIN SIGNAL. AXR. BY DECREASING VALUE OF A1.
Figure 3. Voice/Tone Injection
Power-up Reset
After applying power to the modem, an internally generated reset
pulse is created. The user can also reset the modem externally by
applying the high-going reset pulse to RST for at least 10ms after
the +5V power supply has stabilized. Delay sending commands
to CH1787 for 100-200ms.
MODEM CONTROL
The CH1787 modem may be controlled by sending serial ASCII
command sequences. The commands are sent to the modem
serially on TXD. After execution of the command, the modem re-
turns a serial status message on RXD, to indicate the completion
status of the command.
Training the Modem
The modem must be trained to match the hosts speed and parity
so that it is able to recognize serial asynchronous commands
sent to it by the host UART. The host must retrain the modem each
time a reset signal is applied on RST or after a RESET serial
command. The modem is trained by sending it the following three-
character sequence.
Initializing the Modem
Before commands may be sent to the modem, the modem must
be initialized. This consists of two events: 1) after power-up, a
hardware reset pulse must be applied to the modem, and 2) the
modem must be trained to the hosts speed (2400, 1200, 300bps)
and parity (odd, even, mark, space or none).
+V
cc
+V
cc
+V
cc
22K
3
8
RI
+
1
FROM 1787
PIN 12
LM393
4.7K
2
4
5
6
+
7
+
LM393
10K
10K
4.7uF
.1uF
ISOLATED
ENVELOPE
RING DETECT
Figure 4. CH1787 Application Diagram of Test Circuit
Cermetek Microelectronics, Inc.
Document No. 603-0182 Rev. D (11/98)
3
Table 1. CH1787 Pin Descriptions
PIN
NAME
RING
TIP
I/O
I/O
I/O
O
FUNCTION
1
2
7
8
Directly connects to the telephone line's Ring lead through a user supplied RJ-11C jack.
Directly connects to the telephone line's Tip lead through a user supplied RJ-11C jack.
ANALOG VOICE INJECTED. Transit and receive signal. Let float if not used.
RXA
____
DTR
DATA TERMINAL READY input. ActiveLOW. Switching off DTR can either return modem to command
state, disconnect phone call, or reset modem. DTR should be set LOW when not used.
I
Answer input has two modes of operation depending on its state during reset. 1. When ANS is low
during reset the CH1787 will go off hook in the answer mode, sending answer tone continuously
waiting for an originating tone. This mode of operation is used on a dedicated non dial-up telephone
line (leased line). 2. When ANS is high during reset, the modem will initiate an answer tone whenever
ANS Pin goes low during normal operations. The modem will send the answer tone for 30 seconds
and then stop. If ANS is still low at the completion of the 30 seconds, the modem will attempt another
answer tone sequence as long as ANS is low. Used to manually answer an incoming call.
___
ANS
9
I
VOICE/DATA output is used to switch between telephone and modem line use. When low the modem
is in the control mode and a voice circuit can be switched out, RXA, TXA when high the modem is in
the data mode and the input should be RXD/TXD.
__
V/D
10
11
O
I
RESET input (active high). This input must be asserted HIGH for at least 10 ms to reset the modem.
RESET is then returned LOW for normal operation. If no system reset is available, let this pin float to
enable internal reset.
RST1
__
RI
RING INDICATION: This signal follows the frequency of the ringing signal normally about 20 to 40 Hz
for 2 seconds off for for 4 seconds.
12
13
14
O
-
N/C
No Connection.
___
DSR
DATA SET READY output. LOW indicates handshaking with a remote modem is in progress, and/ or
the data carrier of a remote modem is detected.
O
ORA is an input that is active low. When LOW it will dial one of two stored telephone numbers
depending on the state of the TST pin. The numbers are stored in NVRAM. One is a user defined
number that is loaded in by the user one time with the AT&ZO=(phone number) command. The other
number is a prestored number that is located at Cermetek(408____________) and is in a permanent
loop back answering on the second ring. CH1787 will attempt to connect with the stored number up to
15 tries at 60 second intervals to obtain a successful connection as long as ORA is low. The state of
DCD indicating carrier designates a successful connection. If ORA goes high, further attempts to
connect will be terminated. If after disconnecting from a valid connection, ORA still low the modem will
be unresponsive until ORA is placed high then low. The FCC requireds that automatic dialing attempts
do not exceed 15 to the same number. TST low dial the user stored number.
____
ORA
15
I
____
TXD
TRANSMIT DATA. Serial receive data input. Marking, or a binary 1 condition is transmitted when a
HIGH is asserted.
16
17
I
DIR is an output that indicates when TXD data may be sent to the modem and when RXD data is
valid from the modem. The user should monitor this pin or gate it as shown in Figure 4 to prevent data
from being erronously interpreted by the user's host processer. DIR tells when the TXD and RXD lines
are used for internal CH1787 connection. When DIR is high, valid data is on RXD and TXD. When
DIR is low the user may ignore RXD data and should not place any data on TXD since it will be
ignored by the CH1787.
DIR
IRQ
O
18
19
-
4.7KW resistor to 5V
SLEEP output. A LOW indicates modem is in low power idle mode. Used to control power to other
devices. See Figure 5. Register S24 is the sleep timer register. When the modem is inactive for a
period of time specified by S24, the CH1787 will periodically power down by about 50% of its normal
operating power. I/O lines will become undefined. The default for the CH1787 is that sleep mode is
inhibited. This is done by loading 255 into S24.
_____
SLEEP
O
Note: (1) If VCC has a slow power up ramp time, the internal reset may be ineffective.
Cermetek Microelectronics, Inc.
Document No. 603-0182 Rev. D (11/98)
4
PIN
NAME
I/O
FUNCTION
GROUND.
20
21
22
GND
I
____
DCD
DATA CARRIER DETECT output. LOW indicates a data carrier from a remote modem is detected.
DCD follows carrier is the default.
O
O
__
HS
SPEED INDICATION. High speed select output. A LOW on this pin indicates the modem is
operating at 2400bps.
Originate input (active LOW) places to modem off hook in the originating mode without dialing. Used
to make a connection on dedicated leased lines between two points. The remote modem must be in
answering mode.
____
ORG
23
I
24
25
NC
NC
-
-
No Connection
No connection.
26
27
NC
-
No connection.
SPK
O
SPEAKER - Audio Output. See Figure 5.
___
TST
Test pin input used in conjunction with ORA to steer the dialing between a user stored number and a
pre-stored Cermetek test number. See ORA description.
28
I
____
CON
Connect output indicates a valid 2400bps connection. Can be used in place of DCD and HS to start
the communications. Can be used to indicate the start of an exchange of data.
29
30
31
O
I
____
HNG
The hang-up input pin (active LOW), forces the modem to disconnect. The HNG pin is only functional
when DCD is active (low).
____
RXD
RECEIVE DATA. Serial receive data output. Received MARKING or a binary 1 condition is indicated
by a HIGH.
O
32
33
VCC
GND
I
I
5 Volts + 5% Note: Noise should be less than 50MV.
GROUND.
AAR pin is an input (active LOW). When asserted low then high, CH1787 will auto answer during a
Ring cycle. AAR can be tied low primarily to enable Auto Answer on the first RING. AAR will not
override an AT auto answer condition e.g., S0 > 1.
____
AAR
34
I
Spare pins are available for custom functions. Contact Cermetek with your requirements.
Cermetek Microelectronics, Inc.
Document No. 603-0182 Rev. D (11/98)
5
Modem States
AT[CR]
The modem can be in either a command state or a data mode
state. When the modem is idle, it is in the command state. When
a data call is in progress, it is in the data mode state. The modem
does not recognize commands when in the data state. To recog-
nize commands, the computer must send an escape sequence
to the modem that forces it out of the data mode and into the
command mode.
Where: A and T must be upper case or lower case
[CR] repesents carriage return
The modem will respond with one of the following status mes-
sages, depending on whether it is optioned for abbreviated or
English status messages.
0[CR]
[CR][LF][OK][CR][LF]
(Abbreviated form)
(English form)
The escape sequence consists of a guard time (a period where
no characters are sent to the modem) followed by 3 escape char-
acters, followed by a guard time again. At powerup, the guard
time is set to 1 second minimum, and the escape character is set
as +. These two parameters can be modified via registers S2
and S12.
Where: [CR] represents carriage return (ASCII 13)
[LF] represents line feed (ASCII 13)
The modem may be retrained any time while it is idle.
Another attention sequence A/ is much like the AT sequence
except it repeats the previously entered command specified with
an AT prefix. When given, it must also be in upper case ASCII.
No carriage return is needed.
The modem will stay off-hook with its carrier on after the escape
sequence is received. It returns an OK status message when it is
ready to accept commands. You may re-enter the data mode by
issuing the ONLINE command ATO [enter].
THE COMMAND FORMAT
Typical commands consist of three elements: the attention se-
quence, the commands themselves, and a terminating carriage
return.
AT [commands] [CR]
where: [CR] represents carriage return (ASCII 13)
When entering commands to the modem, the backspace charac-
ter-control-H (ASCII 8)-can be used to edit mistakes. AT and A/
may not be edited however. Multiple commands may be placed
in the command line. A command line may be as long as 40
characters, excluding AT. The command below instructs the mo-
dem to configure itself to not echo characters in the command
mode (E0) and then go to the answer mode.
ATE0A[CR]
AT COMMAND DATA RATE
With the serial interface, the rate is speed sensed for parity and
format.
AT COMMAND SET
The command is divided into three types: basic commands, dial
modifiers and ampersand commands as listed in Table 2.
THE STATUS MESSAGES
The modem responds with a status message after each com-
mand is executed. This status message may either be a single
digit followed by a carriage return or a carriage return and line feed
with a message in English, followed by a carriage return and line
feed.
Dial Modifiers
Function
Pulse Dial
P
R
T
Originate Call in Answer Mode
Touch Tone Dial
The basic status code subsets are enabled with the Xn com-
mand. Where n=0,1,2,3,4 the status codes can be in message
form or result codes selected for the five Xn commands.
X0 - Result Codes 0, 1, 2, 3, 4
X1 - Result Codes 0, 1, 2, 3, 4, 5, 10
X2 - Result Codes 0, 1, 2, 3, 4, 5, 6, 10
W
;
@
!
Wait for Dial Tone
Return to Idle State
Wait for Quiet Answer Command
Flash Hook
Pause
Dial Digits/Characters
,
0-9
A,B,C,D
X3 - Result Codes 0, 1, 2, 3, 4, 5, 7, 10
X4 - Result Codes 0, 1, 2, 3, 4, 5, 6, 7, 10 (factory default)
Cermetek Microelectronics, Inc.
Document No. 603-0182 Rev. D (11/98)
6
Table 2
Register
S0*
S1
S2
S3
S4
S5
S6
Ch1787 Register Summary
Function
Ring to Answer On
Ampersand Commands
Function
*&Dn
&F
*&Gn
*&Pn
*&Sn
&Tn
&V
*&Wn
*Yn
Data Terminal Ready Option
Load Factory Defaults
Guard Tone Option
Make to Break Ratio Selection
Data Set Ready Option
Test Command Option
View Active Configuration
Store active profile
Ring Count
Escape Code Character
Carriage Return Character
Line Feed Character
Back Space Character
Wait For Dial Tone
Wait Time for Data Carrier
Pause Time for Comma
Carrier Detect Response Time
Lost Carrier to Hang-up Delay
DTMF Dialing Speed
Escape Code Guard Time
Bit Mapped Options Register
Modem Test Options
S7
S8
S9
Recall active profile
*&Zn
*&Cn
Store telephone numbers
Not supported
S10
S11
S12
S14*
S16
S18*
S21*
S22*
S23*
S24
S25*
S27*
S28*
Percent Commands
Function
Test Timer
Bit Mapped Options Register
Bit Mapped Options Register
Bit Mapped Options Register
Sleep Mode Inactivity Time
Delay to DTR
%Dn
%J
DTMFAttenuation
Load Secondary Factory Defaults
Bit Mapped Options Register
Bit Mapped Options Register
NOTE: A detailed definition of all commands and registers is available from
Cermetek Microelectronics, Inc.
*= Commands that can be stored in NVRAM.
*=S-Registers stored in NVRAM upon receipt of &W command
AT COMMAND APPLICATIONS
Pause ,
Table 3
Ch1787 AT Command Set Summary
When placing a call from an office with a telephone connected to a
PBX, it may be necessary to dial an access code (usually the digit
9) to get an outside line. Inserting a comma in the telephone
number commands the modem to pause for a specific length of
time. A factory default pause time is 2 seconds.
Basic Commands Function
AT
Attention Code
A
Answer command
A/
*Bn
D
Repeat Last Command
Communications Standard Option
Dial Command
Example: Dial 9, pause, dial number.
Enter AT DT9, 1234567
*E
Off-Line Character Echo Option
Switch Hook Control Option
Speaker Volume Option
Speaker Control Option
On-Line Command
Hn
*Ln
*Mn
On
P
Multiple commas may be used for a greater delay time.
TOUCH TONE AND PULSE DIALING T and P
The modem can use DTMF (touch-tones) or dial pulses when
dialing a telephone number. If the dial command does not specify
which type to use, the modern defaults to the type last specified.
The power-on default value is P.
Pulse Dial
*Qn
Sn
Sn=
Sn?
*Vn
*Xn
+++
,
Result Code Display Option
Select an S Register
Write to an S Register
Read an S Register
Result Code Form Option
Result Code Set/Call Progress Option
Escape Code Sequence
Pause
Example: Pulse dial 9, pause, touch-tone dial number.
Enter: AT DP9, T1234567
Originate a Call in Answer Mode R
?
Returns Last Addressed S Register
Long Space Disconnect Option
On Line Echo character Option
Reset
The D command forces the modem into originate mode. To call
an originate-only modem, dial the number and set the modem
to answer mode via the R (reverse originate). Enter the R
command at the end of the telephone number.
*Yn
Fn
Z
Redial Last Number A/
Use A/, the repeat command, to redial the last telephone
number dialed when a busy signal is received.
Cermetek Microelectronics, Inc.
Document No. 603-0182 Rev. D (11/98)
7
Return to Command State ;
The Serial Interface Lines
The modem can be forced to reenter the command state after
dialing (without hanging up) by ending the dial command with a
semicolon. This is useful when using the modem as an auto
dialer.
The module supports a full RS-232C/V.24 serial interface. Signal
levels are TTL rather than RS-232C level compatible, which al-
lows you to directly connect the modem to your hosts UART with-
out level translating circuitry. A complete description of each signal
follows under Pin Description.
Example: Touch-tone dial 9, pause, dial number, return for
command.
Enter: AT DT9, 1234567;
Two of these lines are all that are required for proper modem
operation: TXD, RXD and DTR. The modem is controlled by send-
ing it serial commands over TXD and can be monitored by serial
status messages returned on RXD.
Result: OK
Automatic Answering
All other serial interface lines may be utilized for the convenience
of your application but are not required by the modem. Unused
outputs (from modem) should be left unconnected. Unused in-
puts should be tied to the proper logic level. See pin description.
The S0 register controls the number of rings that must occur
before the modem answers a call. The register may range in
value from 0-255
S0
S1
S2
S3
DO NOT ANSWER TELEPHONE
ANSWER ON RING 1
ANSWER ON RING 2
ANSWER ON RING 3
S0=255 ANSWER ON RING 255
When S0 is set to 0, the modem will not auto-answer.
Example: Assign the value 6 to S0 to set the modem to answer
on the sixth ring.
Enter:AT S0=6
Result: OK
DIAL A NUMBER D
The Dial command takes the form Dn, where n is a string of char-
acters. In the simplest form, n will be only the digits of the phone
number to be dialed.
Figure 5. Speaker Control Circuit--optional to allow for call
progress monitoring.
Example: Dial number.
Phone Line Connection Guidelines
1) The mounting of the CH1787 in the final assembly must be
made so that it is isolated from exposure to any hazardous
voltages within the assembly. Adequate separation and re-
straint of cables and cords must be provided.
Enter: AT D1234567
In response to this command, the modem dials the telephone
number 123-4567 and then waits for carrier from a distant mo-
dem. If no carrier is detected within a given time (the default time
is 30 seconds), the modem automatically releases the line and
sends a NO CARRIER result code. If carrier is detected, the mo-
dem gives a CONNECT result code and goes on-line, permitting
communication with the distant modem.
2) The circuitry from the CH1787 to the telephone line interface
must be provided in wiring that carries no other circuitry than
that specifically allowed in the rules (such as A and A1 leads).
3) Connection to phone line should be made through an RJ-11
jack.
4) Traces from the modems RING and TIP pins to the RJ-11
jack must exceed 0.1 inch spacing to one another and 0.2
inch spacing to all other traces. The traces should have a
nominal width of 0.020 inches or greater.
The Dial Command may also be issued without a telephone num-
ber. ATD causes the modem to pick up the telephone line without
dialing a number.
5) The RING and TIP traces should be as short as possible and
oriented to prevent coupling other high speed or high frequency
signals onto the host circuit card.
6) No additional circuitry other than that shown in the following
Figure may be connected between the modem module and
the RJ-11 jack.
CONNECTING TO THE HOST UART
Since a modem communicates data serially and most host prod-
ucts handle data in a parallel format, a UART is needed to make
parallel-to-serial and serial-to-parallel translations.
7) The CH1787, the RJ-11 jack, the interfacing circuitry and traces
in between, must be mounted on a circuit board with a 94 V-0
flammability rating.
Cermetek Microelectronics, Inc.
Document No. 603-0182 Rev. D (11/98)
8
8) The supplied FCC registration label must be applied visibly
on the outside of the host product.
9) The host products User Manual must provide the user with
instructions for connection and use as recommended in Sec-
tion FCC Registration.
Changes in Attestation Procedure for Plugs and Jacks
(Name of applicant) attests that the network interface plugs or
jacks used on this equipment comply with and will continue to
comply with the mechanical requirements specified in Part 68,
Sub-part F, specifically the dimensions, tolerances and metallic
plating requirements. The compliance of these connectors will be
assured by purchase specifications and incoming inspection.
Documentation of such specifications and/or inspections will be
provided by the FCC within 30 days of their request for the same.
MOUNTING THE MODEM
The modem contains static-sensitive devices and should only be
handled by personnel and in areas that are properly protected
against static discharge.
There are two mounting techniques that are recommended for
physically connecting the modem to your circuit card; 1) sockets,
and 2) direct soldering.
FOR YOUR USERS MANUAL
The Part 68 rules require the following or the equivalent informa-
tion be provided to the end user of equipment containing a DAA:
The modem may be wave soldered on a circuit card. This part is
hermetically sealed for normal wave soldering process.
Type of Service: The (insert your product name) is designed to be
used on standard device telephone lines. It connects to the tele-
phone line by means of a standard jack called the USOC RJ-11C
(or USOC FJ45S). Connection to telephone-company-provided
coin service (central office implemented systems) is prohibited.
Connection to party lines service is subject to state tariffs.
The socketing approach to mounting eliminates cleaning and
desoldering concerns. When the socket is used, it must make a
solid connection to all modem pins. Failure to do so will cause
unreliable modem operation. Also, steps should be taken to as-
sure that the module remains tightly seated in the socket after the
host product is shipped.
Telephone Company Procedures: The goal of the telephone com-
pany is to provide you with the best service it can. In order to do
this, it may occasionally be necessary for them to make changes
in their equipment, operations or procedures. If these changes
might affect your service or the operation of your equipment, the
telephone company will give you notice, in writing, to allow you to
make any changes necessary to maintain uninterrupted service.
FCC REGISTRATION
The CH1787 is registered with the FCC (Federal Communica-
tions Commission) under Part 68. To maintain the validity of the
registration, you must serve notice to the end user of the product
that contains the modem of several restrictions the FCC places on
the modem and its use. The following notice is recommended
and should be included in the host products USER MANUAL.
Also, the FCC requires that Cermetek make all repairs to the mo-
dem. If repair is necessary after the modem is installed in your
product and has been delivered to your customer, the modem
must be returned to you where it can be removed from the host
product and then forwarded to Cermetek for repair.
Cermetek Microelectronics, Inc.
Document No. 603-0182 Rev. D (11/98)
9
Table 4. CH1787 System Data Mode Compatibility Specifications
Parameter
Specification
Parameter
Specification
2400, 1200, 600 bps character
asynchronous. 0-300 bps asynchronous
Receive Carrier Frequencies Originate +7Hz 2400Hz +7Hz
Asynchronous
V.22 bis, V.22, 212A
Answer
1200Hz +7Hz
Answer 'space' 2025Hz +7Hz
Answer 'mark' 2225Hz +7Hz
Original 'space' 1070Hz +7Hz
Original 'mark' 1370Hz +7Hz
TxD may differ +1%, -25% from modem
output. Offsets will be corrected by
adding/deleting stop bits.
Asynchronous
Speed Range
Bell 103
Asynchronous
Format
Receiver
Sensitivity
OFF to ON threshold-43 dam
ON to OFF threshold-48 dam
8, 9, 10 bits, including start, stop, parity
Two-wire full duplex over public switched
network. On-chip hybrid and billing delay
timers.
Telephone Line
Interface
V.22 bis, 16 point QAM at 600 baud. V.22
and 2212A, 4 point, DPSK at 600 baud.
103 binary phase coherent FSK.
2 dB minimum
Modulation
Hysteresis
Alternate 'ones' and 'zeros' and error
detector, to be used along with most
loopbacks. A number indicating the bit
errors detected is sent to DTE.
Fixed compromise equalization,
transmit.
Adaptive equalizer for PSK/QAM,
receive.
Self Test
Pattern Generator
Line Equalization
Local analog loopback.
Local digital loopback.
Remote digital loopback.
Request remote digital loopback.
Local interface loopback modem with
self test.
Transmit Carrier
Frequencies
V.22 bis V.22,
212A
Originate 1200Hz+.01%
Diagonostics
Available
Answer
2400Hz+.01%
With speaker or quiet screen
messages
Call Progress
Tones Detected
(no dial tone, busy, ring-back, modem
answer tone and voice).
Originate 'space' 1070Hz+.01%
Originate 'mark'
Answer 'space'
Answer 'mark'
1270Hz+.01%
2025Hz+.01%
2225Hz+.01%
Bell 103 mode
Computer Interface
IBM PC/XT/AT bus compatible with an
8250/16450/16550A UART as a serial
controller.
Cermetek Microelectronics, Inc.
Document No. 603-0182 Rev. D (11/98)
10
Table 5. CH1787 Electrical Specifications
Ta=25OC
Sym bol
Vcc
C haracteristic
M in. Typ. M ax. U nits
Supply voltage
Supply C urrent
4.75
5.0
5.25
V
O ffhook operating current
O n hook operating current
Powerdown operating current
50
40
16
75
m A
m A
m A
I
cc
O utputLow Voltage
0.3
0.3
0.4
V
V
V
V
(I =0.4m A)C O N
O L
VO L
(I =5.0m A)D IR
O L
(I =1.6m A)SLEEP,D SR,D C D ,HS,RXD
O L
0.26
(I =4m A)V/D
O L
O utputHigh Voltage
(I =-0.2m A)C O N,D IR
4.45
2.4
4.18
V
V
V
O H
VO H
(I =-100uA)SLEEP,D SR,D C D ,HS,RXD
O H
(I =-4m A)V/D
O H
InputLow Voltage
VIL
TST,O RG,O RA,HNG,AAR,ANS
D TR,TXD
0.95
0.8
V
V
InputHigh Voltage
VIH
TST,O RG,O RA,HNG,AAR,ANS
D TR,TXD
3.3
2.4
V
V
VT+
VT-
Positive Hysteresis Threshold forResetpin
Negative Hysteresis Threshold forResetpin
2.7
1.6
V
V
Auto answer disabled
Command echo ON
All result codes enabled extended
Wait for dial tone before dialing 2 seconds
Detects busy signal
Full word result codes
Pulse dial make/break ratio = 39/61
DSR enabled
Modem enabled DTR
In certain circumstances, it may be necessary for the telephone
company to request information from you concerning the equip-
ment, which you have connected to your telephone line. Upon
request of the telephone company, provide the FCC registration
number and the ringer equivalence number (REN); both of these
items are listed on the equipment label. The sum of II of the RENs
on your telephone lines should be less than five in order to assure
proper service from the telephone company. In some cases, a
sum of five may not be useable on a given line.
DCD enabled
Speaker enabled but off when receiving carrier
Speaker volume set to medium
Local modem will grant RDL request from remote modem
Guard tones disabled
Minimum DTR pulse width = 0.1 seconds
Ring count 01 (CH1786)
Escape code character = 43
Carriage return character = 13
Line feed character = 10
Back space character = 08
If Problems Arise: If any of your telephone equipment is not oper-
ating properly, you should immediately remove it from your tele-
phone line, as it may cause harm to the telephone network. If the
Telephone Company notes a problem, they may temporarily dis-
continue service. When practical, they will notify you in advance of
this disconnection. If advance notice is not feasible, you will be
notified as soon as possible. When you are notified, you will be
given the opportunity to correct the problem and informed of your
right to file a complaint with the FCC. Contact your telephone
company if you have any questions about your phone line.
Duration of wait for dial tone = 02 seconds
Duration of wait for carrier after dialing = 30 seconds
Duration of deal pulse (comma) = 02 seconds
Carrier detect response time = 0.1 seconds
Escape code guard time = 1 second
Length of use after comma = 2.0 seconds
Last carrier to hang up delay = 0.1 seconds
DTMF interdigit delay = 0.1 seconds
DTMF Attenuation = -4dB
In the event repairs are ever needed on the (insert your product
name), they should be performed by (insert your company name)
or an authorized representative of (insert your company name).
For information contact: (insert your company address).
DEFAULT STATUS, PERFORMANCE, AND SPECS
Default Configuration Profile
Async mode selected
2400bps
Bell 212A operation at 1200bps
Even parity
Sleep mode inactivity time = 5 seconds
Long space disconnect disabled
Cermetek Microelectronics, Inc.
Document No. 603-0182 Rev. D (11/98)
11
Table 6. CH1787 Electrical Specifications
Table 7. Other Performance Specifications
Cermetek Microelectronics, Inc.
Document No. 603-0182 Rev. D (11/98)
12
Table 8. Temperature Options
Operating Temperature
Model
0oC to +70oC
CH1787
CH1787ET
-40oC to +85oC
Figure 7. CH1787 Physical Dimensions and Pin Functions
ermetek
C
microelectronics
.
.
406 TASMAN DRIVE SUNNYVALE, CALIFORNIA 94089 TEL: (408) 752-5000 FAX: (408) 752-5004
E-mail: cermstaf@cermetek.com
website: www.cermetek.com
Cermetek reserves the right to make changes in specifications at any time and without notice. The information furnished by
Cermetek in this publication is believed to be accurate and reliable. However, no responsibility is assumed by Cermetek for its use,
or for any infringements of patents or other rights of third parties resulting from its use. No license is granted under any patents or
patent rights of Cermetek.
1998 Cermetek Microelectronics
Cermetek Microelectronics, Inc.
Printed in U.S.A.
Document No. 603-0182 Rev. D (11/98) 13
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