PAK-I_技术文档

PAK-I Data Sheet

AWC

310 Ivy Glen Court

League City, TX 77573

(281) 334-4341

http://www.al-williams.com/awce.htm

V1.4

Overview

The Stamp Pak I is a 32-bit floating-point math

coprocessor with a versatile interface that makes it

easy to interface it with a variety of

microcontrollers including the Basic Stamp from

Parallax. However, you can easily interface the

Pak I with practically any modern microprocessor.

The Pak I can add, subtract, multiply, and divide

numbers between +/- 6.80564693 x 10³⁸. The

smallest number the Pak I can represent is +/-

1.17549435 x 10^-38. Here are some of the Pak I's

major features:

•

Robust, speed independent serial interface

Uses as few as 2 pins to connect to the host

Can connect multiple devices to the same 2

pins with one additional pin per device

Can work with IEEE754 floating point

numbers

Works with Stamp II's ShiftOut and ShiftIn

commands

Synchronous operation – read results when you

are ready for them

•

Adds 8-bits of general-purpose digital I/O pins

Fast 10Mhz speed (can be reduced to save

power)

•

Easy to use

The Pak I is a standard 18-pin IC. In order to

operate it must have a regulated supply of 5V and

connection to a clock element. The Stamp Pak I

includes a 10MHz ceramic resonator that you can

use to clock the chip.

Other than the power and clock connections, the

Pak I requires at least two wires to connect

between your microcontroller (the host) and itself.

Depending on the host's capabilities and your

application, you may want to use more pins for I/O

(up to 5 pins).

If You Need Help

If you require assistance with your PAK-I, please

feel free to contact us. The best way to get support

is via e-mail (stamp@al-williams.com). However,

you may also call between 9AM - 4PM Central

Time at (281) 334-4341. You can also fax to (281)

538-2147. Be sure to check out our Web page for

updates at www.al-williams.com/awce.htm.

Registering Your PAK-I

Please take a moment to register your e-mail

address with AWC. Simply send an e-mail

message to pakreg@al-williams.com. AWC will

not make your address available to other

companies, but we may periodically send you

updated technical notes. You’ll also receive

information about new microcontroller products

and specials.

1

2

3

4

5

6

7

8

9

18

17

16

15

14

13

12

11

10

SIN

SOUT

CLK

RESET

Vss

B0

BUSY/MODE

ENABLE/BUSY

RES2

RES1

Vdd

B7

PAK-I

B1

B6

B5

B4

B2

B3

Pin Connections

Pin Name

Type

Description

18

Busy/Mode Input/Output This pin has two functions. At start up, if the

pin is pulled up by a resistor, the PAK1 uses

this pin as a busy indicator. The pin will read 0

when the PAK1 is not busy. However, if at

startup the pin is pulled to ground, the PAK1

will indicate its busy status on the Enable/

Busy pin.

17

Enable/

Busy

Input or

Open

Collector

Output

If Busy/Mode is pulled high at start up, the

Enable/Busy pin is only an input. Bring it low

to disable the PAK1, or high to enable it.

However, if Busy/Mode is pulled low at start

up, this pin serves as an open-collector I/O

pin. If the host pulls the pin low, it disables the

PAK1. If the PAK1 is busy, it pulls the pin

low.

3

1

CLK

SIN

Input

The host pulses the CLK pin to shift data in or

out of the PAK1.

The PAK1 reads data from this pin. You may

short SIN and SOUT and use the same pin for

input and output if the host is capable of

treating a single pin as an I/O pin.

2

SOUT

Open

Collector

Output

The PAK1 writes data to the host on this pin.

Since the pin is open collector, you'll need a

resistor to 5V on this pin. You may short SIN

and SOUT together to use one pin for I/O

Hardware resets the PAK1 when low.

4

RESET

VSS

Input

Power

Clock

I/O

5

Ground

14

15

16

VDD

+5V

RES1

RES2

B0-B7

Connects to resonator

General purpose I/O

6-

13

Software Commands

Code

$01

$02

$03

$04

$05

$06

Name

Alternate

N/A

Argument

FP

None

DIGIT

None

Returns

Nothing

FP

Nothing

ASCIIDIGIT

Nothing

Description

Load X

Load Y

LOADX

LOADY

READX

SWAP

DIGIT

IEEECVT

Read X

Swap X and Y

Find ASCII digit from X

Convert X to IEEE

format

N/A

$07

FLOAT

$87

None

STATUS

24-bit integer in X to

floating point

Communications check

Convert X from IEEE

format

$08

$09

COMMCK

FPCVT

N/A

None

$22

Nothing

$0A

$0B

CHS

INT

N/A

$8B

None

Nothing

STATUS

X=-X

Convert X to 24-bit

integer

$0C

$0D

$0E

$0F

$10

$11

$12

$13

$14

$15

MUL

DIV

$8C

$8D

$8E

$8F

N/A

None

OPTS

None

DIRS

None

STATUS

Nothing

IBYTE

X=X*Y

X=X/Y

X=X-Y

X=X+Y

Sets option bits

X=|X|

R0=X

SUB

ADD

OPT

ABS

STO0

RCL0

DIR

X=R0

Sets direction register

Reads input byte from

port

RIO

$16

$17

$18

$92

$93

WIO

N/A

OBYTE

None

Nothing

Writes byte to output port

X=Y

Y=X

R1=X

X=R1

XTOY

YTOX

STO1

RCL1

Notes and Key:

•

FP – 32 bit floating point number (see text for format)

DIGIT – A digit number. Zero returns +, -, or space if the number is

positive, negative, or zero. See reference for more details.

•

ASCIIDIGIT – The ASCII representation of the requested digit

STATUS – Floating point error flags

OPTS – Options ( $80 turns on saturation; $40 enables rounding)

R0, R1 – Temporary storage registers

•

DIRS – Byte indicating port directions (0=input, 1=output)

IBYTE, OBYTE – Input or output byte

Using the alternate form of a command prevents it from returning the

status result.

Floating Point Numbers and Errors

The 32-bit floating point representation used by

the Pak I is a modified version of the IEEE754

format. The first byte is the exponent (biased by

127). If the exponent is zero, the number is zero.

The second byte contains the most significant bits

of the mantissa. The most-significant bit is the sign

bit (1 is negative) and the mantissa starts with an

implied 1 before the decimal point. The next two

bytes are the remainder of the mantissa.

This differs from the IEEE745 format (the one

used by PC C compilers, for example) only

slightly. In the IEEE745 format, the sign is in the

most-significant bit of the exponent. The most-

significant bit of the first byte is actually the least

significant bit of the exponent. Otherwise, the two

formats are identical. The Pak I has functions to

convert back and forth between the two formats.

The accompanying disk contains a Windows

program (fconvert.exe) that will convert between a

normal floating point number, the Pak I's format,

and the IEEE745 format. Simply enter the number

you know and the program will display the other

two formats.

The status return bits contain the following

information:

Bit 0 – Integer overflow

Bit 1 – Floating point overflow

Bit 2 – Floating point underflow

Bit 3 – Divide by zero

Bits 4-7 – Reserved; always 0.

A return of zero indicates no error.

Resetting

There are several ways you can reset the Pak I. It

is a good idea to reset the unit before using it, or

any time that you want to make sure it is in a

known state. This is especially true when using the

Stamp. Each time the Stamp resets or wakes up

from sleep, the I/O pins briefly become inputs.

This can fool the Pak I into starting a data transfer.

Always reset the Pak I first.

The best way to reset a single Pak I is to send a

special reset sequence over the clock and data

lines. This has the advantage that it doesn't require

any extra I/O from the host. To send a reset

sequence, bring the data pin to 0 and raise the

clock to a 1. While the clock remains in the 1 state,

bring the data pin high. This will indicate to the

Pak I that you wish to reset. When the clock

returns to a zero state, the Pak I will reset. The

reset doesn't change any register values or port

pins, but it does reset communications to a known

state.

You can get the same result by bringing the enable

pin low and then returning it to high to enable the

Pak I. This is useful if you are connecting more

than one Pak to the same data and clock lines.

You'll need to use the enable pin then anyway, and

it makes sure that the selected Pak is always in a

known state. Using the data sequence method may

be unreliable when using multiple Paks together.

Finally, you can force a hardware reset by bringing

the reset pin low. Holding the clock pin high for

more than 2400mS will also force a reset. This

might be useful if your circuit generates a

hardware reset signal based on a brown-out

detector or other master reset circuit. Normally,

you'll just connect the reset pin to the +5V supply

and allow the Pak I to reset itself on power up. If

you do want to drive this pin, make sure that it is

at 5V for normal operation. You can use a reset

switch or other device if you pull up the reset pin

with a 10K-22K resistor.

Communications

There are several schemes you can use to

communicate with the Pak I. All of them revolve

around a synchronous protocol involving a clock

pin and 1 or 2 data pins. Data is shifted most

significant bit first, and samples at the rising edge

of the clock. All signals are positive logic (that is,

a 1 is a high logic level). The Pak I exposes a

separate input (SIN) and output (SOUT) pins for

hosts that can't easily handle bi-directional I/O

lines. However, for hosts like the Stamp or PIC, it

is a simple matter to tie these lines together since

SOUT is open collector.

Therefore, the minimum number of lines you need

are two. An output for the clock and an I/O line to

connect to SIN and SOUT. You'll connect the

Enable/Busy pin to +5V and use a pull up resistor

to 5V on the Busy/Mode pin. This allows you to

reset the device and communicate with it. The only

problem is, you will have to make sure not to ask

the device for data while it is processing. Most

operations are quite fast, but some operations

(calculating digits and division, for example) can

take as much as 400uS with the provided

components.

For some applications, this isn't a problem. For

example, a standard Basic Stamp II can't operate

fast enough for this to be a problem except for

division and digit calculations. However, you may

want to know when the device is ready to process.

There are two ways you can accomplish this.

If you need to disable and enable the device, you'll

want to drive the Enable/Busy pin. Using this pin

allows you to share the SIN, SOUT, and CLK

lines with other devices that use a similar protocol.

So to connect 5 Paks you'd only need 7 I/O lines (5

enables, 1 SIN/SOUT, and 1 CLK line). You drive

the Enable/Busy pin low to disable the device. If

you don't plan to use this capability, just pull the

pin high with a pull up resistor. If you are using

the Busy/Mode input (see below) you can still use

a pull up resistor, or just tie the Enable/Busy pin

directly to +5V.

If you ground the Busy/Mode input at start up, the

device will also use the Enable/Busy pin to tell

you when it is unavailable. It does this by driving

the line low when it is not ready. That means the

host must drive the pin with an open collector

output if it wants to disable the device. If you don't

need to disable the device, you can just connect the

pin to a pull up resistor and connect the Enable/

Busy pin to an input on the host.

If you want to use a normal output to drive the

Enable/Busy pin, but you still want a busy

indication, you can connect the Busy/Mode pin to

5V through a pull up resistor. Then the Pak I will

use the Busy/Mode pin to signify it is busy (the pin

is high when busy). In this case, the Enable/Busy

pin is always an input and you can drive it

normally.

Many commands have an alternate form. These

commands are the ones that return the floating

point error flags on completion. Using the alternate

form suppresses the status return value.

One thing to note about the status returns. All of

the commands that take any significant amount of

time will return zeros in the top bit of the response.

You can use this as a form of busy indication if

you are unwilling to use any other pins. Simply

read the data pin until it reads zero. This indicates

that the device is sending the response. The

READX and RIO commands do not follow this

convention, but they take very little time to

execute anyway (less than 8uS).

To summarize, here are the ways you can

synchronize with the Pak I:

1. Delay long enough to insure the operation is

complete

2. Monitor the Enable/Busy line while Busy/Mode

is grounded. If you bring Enable/Busy low it

indicates that the Pak I is disabled. If the Pak I

brings the pin low, it means it is engaged in

operations.

3. Place a pull up resistor on the Busy/Mode pin.

This will cause the Busy/Mode pin to be high

when the Pak I is busy.

4. On commands that return status or ASCII digits,

you can wait until the data pin goes low.

Command Reference

ABS

Finds the absolute value of X. That is if X

is negative, negate it. If X is zero or

positive, leave it alone.

ADD

Adds X and Y leaving the result in X. Y is

unchanged. This command may take

approximately 110uS in the worst case.

CHS

Negates the X register.

COMMCK

This command causes the Pak I to issue a

$22 response. You can use this to check

communications. The Pak I will always

respond with $20 plus the version number.

DIGIT

The DIGIT command accepts a single byte

as an argument and returns a single byte. If

the input byte is a zero, DIGIT returns an

ASCII +, and ASCII – or a blank character

depending on if the X register is positive,

negative, or zero. You can use this as a

SGN function, but it is mostly useful when

writing numbers in readable form.

If the input number is less than $7F, DIGIT

returns the ASCII digit from the X register

that you ask for. For example, if X contains

13.141 and you issue a DIGIT 1 command,

the return will be '3'. DIGIT 2 will return

'1'.

Numbers greater than $80 return ASCII

characters to the right of the decimal point.

So using the same example, if you issue a

DIGIT $81, the return will be '1'. DIGIT

$82 will return '4'.

This command does not affect the X or Y

registers. It may take some time to execute

depending on the digit you request, and the

number in the X register.

This command performs a complex

algorithm which involves converting the

number to an integer and back to a float in

several places. Since integer to float

conversion is limited to 24 bits, this places

an upper limit on the size of the number

you can convert with DIGIT. Note that this

does not apply to using it as a replacement

for SGN. If you operate on a large number

(or a number with many significant digits)

and an intermediate result exceeds 24 bits,

you may get an incorrect answer, or the

PAK may fail to converge.

DIR

This command allows you to set the

directions of the 8 bit I/O port. On power

up, all pins are inputs. Setting a bit to 1 in

the DIR command causes the

corresponding I/O bit to be an output. So

issuing a DIR $83 will make B7, B1, and

B0 outputs and all other pins inputs.

DIV

Divides X by Y leaving the result in X. Y

is unchanged. This command may take

approximately 380uS in the worst case.

FLOAT

The float command converts the 24-bit

integer in the X register's mantissa into a

floating point number ready for

calculations.

IEEECVT, FPCVT

These commands convert the X register to

IEEE format, or to the Pak I's internal

format. If you load an IEEE number, you

must convert it before using it in

calculations. Once you convert to IEEE,

you must convert back before using the

number in any calculations. These

operations are very fast, so it isn't a

problem to convert several times.

INT

Converts the X register to a 24-bit integer.

To read the integer, issue a READX. In

order to continue calculations with the

same number, you'll need to issue a

FLOAT command, or reload the X register.

It is often quicker to use a STO command

to save the X register, perform the INT

command, read the result, and then RCL

the original contents.

LOADX, LOADY

These commands take the next four bytes

you send and places them in the X or Y

register. The format is exponent first,

followed by the mantissa (most significant

bit first). You can also load integers or

IEEE format numbers for conversion using

this command.

MUL

OPT

Multiplies X and Y leaving the result in X.

Y is unchanged. This command may take

approximately 240uS in the worst case.

Sets options. Send the option byte after this

command. Using $80 turns on saturation

(which represents over and underflows as

minimum and maximum values). Using

$40 enables rounding. If this option is not

on, results are truncated which is faster, but

less accurate. On a power up reset, both

flags are off.

RCL0, RCL1

Recalls register 0 or 1 to X. The register is

unchanged.

READX

This command sends the four bytes that

comprise the X register to the host. The

host must clock in 4 bytes. The first byte

will be the exponent, and the following

three bytes the mantissa (MSB first). Note

that if you execute an IEEECVT command

the result will be in IEEE format. If you

execute an INT command, the exponent

will be meaningless, and the mantissa will

be the 24 bit binary integer result.

RIO

This command reads 8 bits from the I/O

port. Of course, bits set to outputs will read

whatever you are writing to them. The Pak

sends the byte immediately.

STO0, STO1

Stores X in register 0 or 1.

SUB

Computes X-Y leaving the result in X. Y is

unchanged. This command may take

approximately 110uS in the worst case.

SWAP

WIO

Swaps X and Y

This command writes 8 bits to the I/O port.

This only affects pins that are set as

outputs. Send the byte immediately after

the command.

XTOY

YTOX

Stores X in Y without changing X.

Stores Y in X without changing Y.

Example 1. Connections to Stamp or similar host

Typical Circuits and Software

Connecting the Pak-I to its external components is

simple. Supply 5V to Vdd and ground the Vss pin.

Connect the two outer pins of the ceramic

resonator to the RES1 and RES2 pins (the order

does not matter). Ground the center pin of the

resonator. Connect the RESET pin to 5V. For the

simplest mode of operation connect the ENABLE/

BUSY pin to 5V and the BUSY/MODE pin to 5V

through a pull up resistor (10K-22K). Of course,

you'll also need to make connections to the host

microprocessor. You may also want to make

different connections to ENABLE/BUSY and

BUSY/MODE if you want to use different

methods of synchronizing.

If you are using the Basic Stamp II or Basic Stamp

IISX, you'll have no problems using the ShiftIn

and ShiftOut commands. Many Basic Stamp-

compatible compilers have these commands too. If

you don't have access to these commands, don't

worry. Here is some simple code (written in simple

PBasic) that shows the actions you have to take:

'

B1 is the byte to shift

shiftoutput:

output datapin

for b7=0 to 7

' Set data pin to 0 or 1

low datapin

if (b1 & $80) <> $80 then so0

high datapin

so0:

b1=b1*2

' shift byte left

high clkpin

low clkpin

' could use pulsout

' B1 is byte to input byte

shiftinput:

input datapin

b1=0

for b7=0 to 7

b1=b1*2

b1=b1 | in15

high clkpin

low clkpin

return

You'll find a library of Basic Stamp II routines that

allow you to access the PakI on the companion

disk. Here is a simple program that counts from 1

to 1000 while blinking an LED connected to the

PakI's B4 pin:

i var word

gosub FReset

' reset

' set B4 to output

fpx=$10

gosub IODir

gosub FZeroX

gosub FSwap

fpx=1

' x=0

' x<>y

gosub FLoadInt ' x=1.0

gosub FSwap

' x<>y so x=0.0, y=1.0

Debug "Start...", CR

for i=1 to 1000

fpx=i//2*$10

gosub IOWrite ' Blink light

gosub FAdd

fpx=4

gosub FDump

' x=x+y

' print it out

Here is the same program, but instead of loading 1

as an integer, it loads .5:

i var word

gosub FReset

fpx=$10

' reset

gosub IODir

gosub FZeroX

gosub fSwap

fpxhigh=$7e00

fpxlow=0

' x=0

' x<>y

' x=.5

gosub FLoadX

fpx=3

gosub FDump

gosub FSwap

' x<>y so x=0.0, y=0.5

Debug "Start...",CR

for i=1 to 1000

fpx=i//2*$10

gosub IOWrite

gosub FAdd

fpx=4

' x=x+y

gosub FDump

Frequently Asked Questions

Q: How can I load a particular number to the X or

Y registers?

A: There are two methods. First, you can use the

fpconvert program to determine the 32-bit number

that corresponds to the number you want. Then

pass it to the FLoadX (or FLoadY) subroutine.

You can also use the LOADX or LOADY

command directly. The other way you can load a

number is via the FLOAT or FLoadInt commands.

Q: Can I run the Pak I from a different clock

source?

A: Yes. Any crystal or ceramic resonator up to

10Mhz may work. Remember, the ceramic

resonator has capacitors that you will have to

supply if you use a crystal or a resonator without

capacitors. You'll use two capacitors (one on each

RES pin). You'll have to experimentally determine

the values. Start with about 15pf and work up to as

much as 100pf for very low frequency crystals.

You can also feed an existing TTL-level clock

signal into pin 16.

Q: Will running the Pak I at a lower speed reduce

its power consumption? Will it run faster.

A: Yes running at slower speeds will save power.

You will probably not have success overclocking

the Pak I. However, contact AWC for information

on faster devices and other customizations.

Q: Why are my results backwards?

A: Make sure you are using MSBPRE with the

ShiftIn command and not MSBFIRST. Use

MSBFIRST with the ShiftOut command.

Q: Is there a second source for the PakI?

A: No. However, if you have a high-volume

application and you are concerned about

availability, contact AWC about obtaining a

license to produce your own Pak I's or obtain them

from third parties.

Q: How can I compare two numbers?

A: To compare X and Y, store X away (using one

of the STO commands). Subtract Y from X and

then call DIGIT 0 to determine if the result is

positive, negative, or zero (this operation is very

fast). Then restore X. Of course, if you don't mind

destroying X, you can skip the STO and RCL.

Q: Can the PakI handle square roots?

A: Not directly. The Pak II, however, will. You

can use the FSqrt function to calculate a square

root indirectly, however.

Q: Can I use more than one Pak at one time?

A: Yes. You can drive multiple Paks on the same

data and clock lines as long as you only enable one

at a time. Of course, you could keep them always

enabled if you use separate data and clock lines.

You can use a resonator for each, or you can use a

single resonator and feed pin 15 of the Pak with

the resonator to pin 16 of the other Paks (this will

only work for a small number of Paks).

Basic Stamp II Library

On the enclosed disk you'll find FUTIL.BS2 which

contains a simple library for the PAK-I. The calls

in that file appear on the next page.

Call

Function

Notes

FReset

FAdd, FSub, FMult,

Reset the coprocessor

Basic operations

Always call first

Operate on X and Y

FDiv

FSqrt

Square root approximation Newton

approximation;

destroys all registers

FSquare

Square X

FChs

Change sign

FAbs

FSto0, FSto1, FRcl0,

FRcl1

Absolute value

Store and recall scratchpad

FLoadX, FLoadY

Load values to X and Y

Place hex numbers

in fpxhigh and

fpxlow

FZeroX, FZeroY

FPI

Fe

FLoadInt

FReadX

Load 0 to X or Y

Load X with pi

Load X with e

Load integer to X

Read X

Place integer in fpx

Places result in

fpxhigh and fpxlow

FInt

Read X as integer

Leaves result in

fpxhigh and fpxlow

FSwap

Swap X and Y

FGetDigit

Decode an ASCII digit or

compute signum

Place digit number if

fpx, returns in

fpdigit

FDump

Dump number on debug

terminal

Set fpx to number of

digits before decimal

point

FOption

FXtoY

FYtoX

IODir

Set options

Y=X

X=Y

Options in fpx

Set I/O direction register

Directions bits in

fpx

IOWrite

IORead

Write to I/O port

Read from I/O port

Data out in fpx

Returns byte in fpx

Specifications

Absolute Maximum Ratings

Parameter Minimum Typical

Maximum

5.5V

Supply

voltage

Vdd rise

time on

power up

Supply

current

4.5V

5V

-

.05V/ms

-

5mA

10mA

DC Characteristics (at 10MHz)

Ambient temperature under bias

Storage temperature

-55°C to +125°

C

-65°C to +150°

C

Voltage on VDD with respect to VSS

Total power dissipation (1)

Maximum current out of VSS pin

Maximum current into VDD pin

Maximum output current sunk by any I/O

-0.3 to +7.5V

800 mW

150 mA

100 mA

25 mA

Maximum output current sourced by any I/

O pin

20 mA

Maximum current sunk by B0-B7

Maximum current sourced by B0-B7

150 mA

100 mA

Notes

When configured as inputs, all of the general-

purpose I/O pins have weak pull up resistors

(about 20K) internally configured.


型号：	PAK-I
厂家：	ETC
描述：	310 Ivy Glen Court 310常青藤苑峡谷
文件：	总28页 (文件大小：140K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

PAK-I [ETC]

相关型号：

PAK-II

PAK-III

PAK-IV

PAK-VA

PAK-VI

PAL-S25G3817-27C

PAL-S35G6600-18C

PAL-S35G6600-20C

PAL-S35G6600-27C

PAL-S35G6600-30C

PAL02-2

PAL020CABP