Just out of interest, did you characterize the PLL jitter on this part? When I was experimenting with STM32s I found there was quite significant clock jitter even with the spread-spectrum clocking turned off. It did average to zero over any reasonable sampling period, but it also made individual timestamps quite noisy. - Pete On Mon, Feb 19, 2024 at 3:10 AM Jeremy Elson via time-nuts < time-nuts@lists.febo.com> wrote: > Hi Juan, > > The STM32G4 is a great device for timestamping - it's what my timestamper > uses! It can run up to 170MHz which gives you a timing resolution of just > under 6ns. > > As you noticed, some of the models (e.g. the STM32G474) do have the HRTIM > peripheral, and that was the source of my original excitement for > time-nuttery. It has a DLL of 32x on top of the 170MHz system clock, which > made me *think* I could use it to get 184ps resolution from a $10 chip. > Unfortunately when I sat down to finally write the code I realized that the > HRTIM only gives you that kind of resolution for *output* waveforms. Input > capture still runs at the system clock frequency. > > In any case, I think it's still impressive to get 6ns resolution out of a > $5 chip (the STM32G431). My code and schematics are all open source; see: > https://github.com/jelson/rulos/blob/main/src/app/timestamper/timestamper.c > . My prototype board uses the STM32G431, with a 10MHz reference clock input > from the oscillator of your choice. I've used both GPSDOs and Rubidium > LPRO-101's. My board has a small analog circuit that changes the 0-centered > AC input of the reference clock to an above-zero waveform that can be used > as the stm32's system clock. The stm32 chip has an onboard PLL that I > configure to multiply the 10MHz ref clock up to a 170MHz system clock. Then > I use the input capture feature of the chip to acquire timestamps. > > -Jeremy > > > > On Thu, Feb 15, 2024 at 8:04 AM Juan Solano via time-nuts < > time-nuts@lists.febo.com> wrote: > > > Thanks a lot guys for pointing me at the TICC, definitely I will have a > > look. > > > > Jeremy, interesting that you are using an STM32. I have an STM32G4 > > lying around and I should have looked into it as I think it has some > > high resolution timer that perhaps could be handy for this kind of > > stuff, is that what you are using in your project? Your oscillator > > recomendation sounds great! > > > > Regards, > > Juan. > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe send an email to time-nuts-leave@lists.febo.com > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com