PAK-III Datasheet, PDF (8/14 Pages) List of Unclassifed Manufacturers – Using the PAK-III I/O Coprocessor

CHECK
Communications check and version identify. Always returns $31 ($3 for this
PAK, 1 for version number).
COUNT
Count returns the number of transitions on the specified pin during the interval
you ask for. Send the period (16-bits) in 8uS units. The PAK-III will return a zero
and the 16-bit count.
FREQOUT
This command emits a tone for a specified period on a particular pin. You'll want
to filter the output with an RC network to filter the high-frequency noise
generated. Send the frequency in hertz (two bytes) and the duration in
milliseconds (also two bytes). The PAK-III returns 0.
FREQOUT2
This command emits two tones for a specified period on a particular pin. You'll
want to filter the output with an RC network to filter the high-frequency noise
generated. Send the first frequency in Hertz (two bytes), the second frequency in
Hertz (two bytes) and the duration in milliseconds (also two bytes). The PAK-III
returns 0.
GETRAND
You can use this command to read a number that is suitable for seeding a random
number generator. This number is actually a free-running clock inside the PAK-
III. The PAK-III will return a zero and the quasi-random byte.
HIGH
Forces the specified pin to be an output and outputs a 1 on that pin. Always
returns 0.
INPUT
Converts the pin number to an input. Always returns zero.
LOW
Forces the specified pin to be an output and outputs a 0 on that pin. Always
returns 0.
OUTPUT
Changes the specified pin to an output. Always returns 0.
PULLON/PULLOFF
These commands enable and disable the weak pull up resistors (about 20K) on the
8 I/O ports. The default is disabled. The return value is always 0.