PPI Auto Reset Timer In Counter Mode

[snoopy20]

  // motion frequency capture
  NRF_PPI->CH[CFG_PPI_TASKER_CHANNEL_MOTION_CAPTURE].EEP = CFG_TASKER_PIF_TIMER->EVENTS_COMPARE[1]; // wire timer compare
  NRF_PPI->CH[CFG_PPI_TASKER_CHANNEL_MOTION_CAPTURE].TEP = CFG_MOTION_PIF_TIMER->TASKS_CAPTURE[1]; // wire ppi to timer capture
  NRF_PPI->CH[CFG_PPI_TASKER_CHANNEL_MOTION_CLEAR].EEP = CFG_TASKER_PIF_TIMER->EVENTS_COMPARE[1]; // wire timer compare
  NRF_PPI->CH[CFG_PPI_TASKER_CHANNEL_MOTION_CLEAR].TEP = CFG_MOTION_PIF_TIMER->TASKS_CLEAR; // wire ppi to reset count
  NRF_PPI->CHENSET = 1 << CFG_PPI_TASKER_CHANNEL_MOTION_CAPTURE_POS;  // enable ppi channel
  NRF_PPI->CHENSET = 1 << CFG_PPI_TASKER_CHANNEL_MOTION_CLEAR_POS;  // enable ppi channel

The only way I can see to do it is by two separate PPI calls. So Timer1 "tasker" is firing both the capture and clear... but will they execute sequentially?

[Edvin]

I don't think I am able to follow the logic behind the counter mode and the way you are measuring, but is this working?

If you are using the softdevice, just don't use the TIMER0 and RTC0 for anything else. The softdevice will use them as well, but you may already know this.

BR,

Edvin

[snoopy20]

I'm pretty sure the softdevice also uses RTC1 although I can't recall what for off the top of my head.

I haven't tested the approach yet but see no reason why it won't work. All I'm doing is running a timer at 2Hz and a timer that clocks of an external pulse, so I know how many pulses have occurred every 0.5s.

[Edvin]

I don't know what Softdevice you are using, so I'll do an educated guess. For the S112, you can check the requirements here.

BR,

Edvin

[snoopy20]

Off the top of my head an application uses nrf52sdk which uses rtc1 to time calls to SoftDevice so although it's not used per-say it is as good as.

[Edvin]

RTC 1 is by default used by the app_timer. Perhaps that is what you mean.