Issue with nActiveChannels in AI module

PrsaLab

Hi Josh,

We are having the following issue with the AI module. We want to log data on 3 AI channels.

When we set nActiveChannels=3, data on channels 1 and 2 is logged fine, but data on channel 3 does not correspond to our signal. It is instead a sawtooth waveforem that looks like some sort of counter signal.

When we set nActiveChannels=5, data on channels 1, 2 and 3 is logged fine. However, the counter-like signal then appears on channels 4 and 5.

When we set nActiveChannels=8, data on all channels is logged fine.

We can work with this by setting nActiveChannels=5 but it is not optimal in terms of speed and memory since we only need 3 channels.

I attached below a figure of the logged data waveforms illustrating this issue.

Any ideas?

Thanks.

https://drive.google.com/file/d/1mChxqkQFaMdbyFM16rMALaK6WUCPYTkZ/view?usp=sharing

Josh

Hi PrsaLab,

I'm not sure what to make of this phantom sawtooth.
I'll try to replicate the issue.
What instruments do you have connected to Ch1, 2 and 3?

-Josh

PrsaLab

Hi Josh,

Thanks for you prompt reply. The instruments connected to the 3 channels are:

- Ch. 1 and 2: angular position of dc motor (analog output from a quadrature decoder to analog converter).
- Ch. 3: Wire1Out from Bpod.

Josh

Hi PrsaLab,

Another user wrote in with the issue, and I think we have a solution here.

Please try it and let us know if it works for you.

Thanks,
-Josh

PrsaLab

Hi Josh,

Thanks!
We uploaded the new firmware and the phantom sawtooth is gone. We can now set nActiveChannels to 3 without any issues.