Derivative term in the PID

[Bentwin2002]

Do you know why the D term in the PID was deactivated? Has anyone had any success reactivating and using the D term?

[michaelcroquette]

The D term was unused in our experiments most of the time so we removed it. It is active in the default RedPitaya PID module if you really need it.

[mixgreen]

The D term was unused in our experiments most of the time so we removed it. It is active in the default RedPitaya PID module if you really need it.

Is that mean i can't use the D term in pyrpl? if i really need it , is that posiable to uncomment the code to use it?

[michaelcroquette]

Actually you can ! I thought the derivative had been disabled in fpga code but it was actually uncommented in #22. There is a comment in the code saying "Derivative - 2 cycles delay (but treat as 1 cycle because its not functional at the moment" but I'm not sure what it means.
The python code of the PID module was commented in #299 but there is no mention of this modification in the commit description.
Anyway you can try and see ! It looks like the fpga code is the same as the original one from redpitaya so I think it should work. If it works we will uncomment it.