RE: Pico low jitter PID controller

Jan Cumps — Sun, 25 Oct 2026 19:09:20 GMT

I tried this same example, on the RISC-V cores of the RP2350

The comparison is unfair at the moment because:

I don't have a fixed point library for the RISC family (yet), so I have to use floating point math
the RISC cores don't have an FPU, They can't use the ARM FPU, so have to do all floating point math in C on the CPU, that doesn't have floating point instructions.

The PID loop time is 11 µs.

I'll try to find q fixed floating point lib for the RISC, either a Q15 or Q31 version. The results should be fairly similar to ARM then.

RE: Pico low jitter PID controller

shabaz — Sat, 24 Oct 2026 14:43:18 GMT

Hi Jan,

Neat project. This seems like a really clean way to drive the PID updates, all clocked from the ADC rate! Also, interesting how you ran the function from RAM for lower latency. I didn't know that was possible.