RE: Sampling ADC synced with PWM through PPI

Edvin — Fri, 25 May 2018 13:44:42 GMT

Hello,

I saw your other case here. I suggest you do as Rune Holmgren suggested, to use the bare metal implementation of the PWM.

I attached a project that uses the TIMER peripheral with the GPIO peripheral to generate a PWM with two channels. If you only need one, just remove everything that looks like it belongs to PWM1, and not PWM0.

devzone.nordicsemi.com/.../ppi_5F00_double_5F00_channel_5F00_pwm.zip

If you only need one PWM signal, I suggest that you remove the PWM1, and use the FORK command to attach the SAADC sampling to the event:

(uint32_t)&NRF_TIMER3->EVENTS_COMPARE[PWM0_TIMER_CC_NUM];

Just like the PWM1 TASK_SET is forked.

But you must remove the PWM1 for this, since you can only have one fork per PPI channel.

It should look something like:

NRF_PPI->FORK[PWM0_PPI_CH_B].TEP = (uint32_t)&NRF_SAADC->TASKS_SAMPLE;

Best regards,

Edvin