I have devices with several similar boards, all of which are basic computers (with CPU, RAM and ROMs etc.). They all interface to the I/O unit via a standard connector, although the connectors aren't all wired the same, unfortunately. The I/O unit comprises of a switched mode PSU (+12V +5V -5V), various switches (tied to ground) and 15kHz RGB video.
I would like to use one I/O unit as a test rig, and be able to switch the lines accordingly for each board automatically. I will probably use an Atmel device to keep note of the configurations, as I have several spare.
My main issue is that some of the pins carry voltage. Unfortunately, even these vary from board to board. The PSU is rated at 15A on the +5V line, 3A on the +12V line and 1A on the -5V line, although I'm sure most of the boards don't draw anywhere near that amount of current (I seem to recall 5A being plenty for one board on the +5V line). There are quite a few lines on the connector.
All that I can think of is using relays, but as there are quite a few lines (around 60-70, I believe), that's an awful lot of relays!
Can anyone think of a solution?
Best Answer
If the connector has a ribbon cable, identify the problematic signals and cut or re-route these lines on the cable. If this becomes too much of a rat's nest or you don't have access to the individual signals, you could manufacture a breakout board for each processor board to standardize the connections to your I/O module.