On Fri, 29 Aug 2003, THE NELSONS wrote:
> Has anyone done anything with trying to communicate with a computer by
> means of the keyboard port.  I wanted to make a custom keyboard  that
> was easy to program for different applications.  I have some
> disabilities and there are many ways this could help.

  I have just started writing code for ps/2 interfacing, as the eBOX
sis550 chipset computer I am planning to send to 35km altitude does not
have serial ports and I want to read GPS data in.  I am writing
experimental code to use 16lf628 PWM output for ps/2 clock and normal
pull-up tristate RB pin for data.  Using PWM with one interrupt per bit
allows other tasks to crawl on while sending data, depending on bit
speeds.  USART is free for receiving from GPS module.

  The code with timings that allow humans to see clock/data leds blink is
here:

http://www.iki.fi/hyvatti/kansat/ohjain/

  I have not yet interfaced to actual ps/2 port.

  Some answers to obvious questions:  why not use USB-RS232 adapter?
Because I am planning on using the same PIC for controlling the power unit
for eBOX computer, to put it to sleep and wake up when needed, maybe
controlled by GPS output too.  And it is fun.  PS/2 interface has +5V
power.  Will it work?  I do not know.  The timings may get tricky.

--
Foreca Ltd                                           Jaakko.Hyvatti@foreca.com
Pursimiehenkatu 29-31 B, FIN-00150 Helsinki, Finland     http://www.foreca.com

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