low level device control

Greg Saunders lnx at telusplanet.net
Thu Aug 23 04:26:26 CEST 2001


First, let me state that I am a python newbie but absolutely love the 
language and am having a great deal of fun with it. Hail to the BDFL.

Here's the challage and I'm not exactly sure where to start.

I need to control two pairs of pin outs on a hardward device. The device 
has four pin outs. PIN1 sends a 12 volt pulse and is returned to ground 
via PIN2 if the two are shorted. PIN3 and PIN4 are either shorted, or 
not, putting the device in ready/not ready state respectively. The pulse 
on PIN1 needs to be read and counted (one count per pulse).

PIN1 - pulse
PIN2 - used to return pulse to ground if shorted

PIN3 - creates a circuit with PIN4 if closed
PIN4 - as above and puts the device into READY if shorted with PIN3

Here's what I want to do. I want to use python and a serial connection 
to read the pulses on PIN1 and be able to open and close the circuit 
programmatically on PIN3 and PIN4.

I can hack together a custom cable to tie into the harness.

My program knowledge is limited and my python knowledge is even more 
limited (but I'm learning quickly :-) but not quick enough). I've 
scanned throught the "termios" library reference but it does not appear 
to be what I'm looking for.

Any help would be much appreciated.

Greg Saunders




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