About Svan .41

Svan .41 · 2021-11-03

In the capture/compare ISR, I want to program the next CCR1 value and the associated action: to change the output to active or inactive when CNT matches CCR1. For this I need to set TIM1_CCMR1 OC1M to 0001 or 0010. However, as soon as I program OC1M ...

Svan .41 · 2021-11-05

The jitter is due to HSI16. The RC oscillator is too inaccurate. Will try a crystal instead. Thank you for your insight!

Svan .41 · 2021-11-05

So, I checked the jitter with another piece of SW (with a more normal method of PWM generation). It does look like something is wrong with the clock I'm using (HSI16)int SetupClocks(){ // MSI clock at 4MHz is used as the system clock from reset. T...

Svan .41 · 2021-11-04

Thank you for sticking ;)The goal is to calculate how long a pulse needs to be directly after it has started. This is for some control algorithm:For each of the 3 outputs the start is 120 degrees delayed. The length of output is to be controlled indi...

Svan .41 · 2021-11-03

> Timers aren't stopped by default during debuggingSo it seems, thanks. But that means my jitter comes from somewhere else? It is approx. 800 PPM (!)Would increasing the prescaler do that? It would reduce my pulse width timing resolution.

Svan .41 · 2021-11-03

I am stepping through the code, and watching on a PicoScope. When I let the code run freely, the pulses appear to be jittering, hinting that it is the code that does the edges and not the Capture Compare (which should be virtually jitter free)

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OC1M set active/inactive on match immediatly changes output

Re: OC1M set active/inactive on match immediatly changes output

Re: OC1M set active/inactive on match immediatly changes output

Re: OC1M set active/inactive on match immediatly changes output

Re: OC1M set active/inactive on match immediatly changes output

Re: OC1M set active/inactive on match immediatly changes output