GPIO PA0 through PA7 cross controlling each other

Steve 2018-12-02 00:15:24 UTC #1

While connecting multiple potentiometers to my Axoloti, GPIO pins starting with PB and PC work as expected. When I connect to any pin starting with PA, other pins starting with PA react to the single potentiometer connected to a single pin. It is somewhat random, but PA0 through PA3 tend to act together, as do PA4 through PA7.

Any thoughts or suggestions would be great appreciated as I really need those 8 analog inputs.

Gavin 2018-12-02 00:56:41 UTC #2

how did you connect them ? do you have a photo ?

Steve 2018-12-02 01:27:01 UTC #3

Steve 2018-12-02 01:28:58 UTC #4

The wiper pin on the pot is connected to the analog pin on the Axoloti. This is the same way the pots are connected to the B and C pins which work correctly.

I have tested for a short and there is no continuity between the pins.

Steve 2018-12-02 01:32:25 UTC #5

This is the screenshot of the GPIO test showing PA1, PA2 and PA3 all moving when only the pot connected to PA1 was moved.

Gavin 2018-12-02 22:18:22 UTC #6

Everything looks good from your pic,
You might need to do testing one pin at a time to see if there are any issues with them individually. Try some of the unused pins as well. Although one thing I would like to ask, the chart in PA1, PA2 & PA3, why is there an immediate drop in the signal, then the gradual increase ? If you want to see if it is working correctly, see if the signal can start at 0 increase to max with a steady turn of the pot, then reverse back to 0 in reverse

Steve 2018-12-02 22:29:08 UTC #7

Thanks for the response @Gavin. After some experimenting, I found that connecting unused pins to ground seems to have solved the problem.

I haven't seen any ill effects from grounding them, so it looks like I can get on with my patching!