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You should be able to power the AVR board and CPLD boards independently, eg. from their respective USB connectors (if that is how they are normally powered).
All you really need to do is to connect the signals on the GPIOs on the respective boards, and connect a few ground pins.
The ground pins establish the common reference, and provide a path for return currents. You might be able to get away without the ground, if both boards are being powered from a single computer, however, its would be a good idea to connect grounds on the respective GPIO connectors.
Cheers,
Dave
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Thank you very much for a quick response! I don't have a AVR board, just a AVR Mega 168 sitting on a breadboard for prototyping purposes. I can power it up with a 3.3V source from a LM317.
Now, all I have to do is connect the ground of the LM317 to the GND pad on the development board? This will provide a common reference point and I ought to be ready to go.
Am I correct in my understanding?
Honored Contributor
