nRF52832 how to use PPI to do a capture compare on a timer, and also disable that compare?

RE: nRF52832 how to use PPI to do a capture compare on a timer, and also disable that compare?

nothingmuchyou — Mon, 26 Jul 2021 20:46:12 GMT

Can a nordic engineer give an answer to this question? What's the best way to enable/disable timer channels without stopping the channel (in the case that other timer channels are in use?)

RE: nRF52832 how to use PPI to do a capture compare on a timer, and also disable that compare?

Kenneth — Wed, 05 Feb 2020 10:35:55 GMT

Maybe the \nRF5_SDK_16.0.0_98a08e2\examples\peripheral\timer ?

You need to disable it on NRF_TIMER_EVENT_COMPARE0.

RE: nRF52832 how to use PPI to do a capture compare on a timer, and also disable that compare?

Philip — Wed, 05 Feb 2020 09:27:09 GMT

Hi Kenneth.

Are there any examples in the SDK on how to do that?

RE: nRF52832 how to use PPI to do a capture compare on a timer, and also disable that compare?

Kenneth — Wed, 05 Feb 2020 07:38:37 GMT

[quote user="philipm"]Basically how do you use a timer compare to trigger a capture only once, and then disable that capture which the timer carries on running?[/quote]

In such case you must enable an interrupt on the specific timer compare to disable it.

RE: nRF52832 how to use PPI to do a capture compare on a timer, and also disable that compare?

Philip — Tue, 04 Feb 2020 16:44:35 GMT

I think I have found an issue. I configure 2 compares for my timer4, but I read in another question that 'NRF_TIMER_SHORT_COMPARE1_CLEAR_MASK' will clear the whole timer not just the compare?

What is the point of 'NRF_TIMER_SHORT_COMPARE1_CLEAR_MASK' if you can't clear individual compare channels? I don't want the clear the whole timer at this 5mS compare event, just the compare. Is there a way to do that?

Basically how do you use a timer compare to trigger a capture only once, and then disable that capture which the timer carries on running?

static void timer4_init(void)
{
    // Check TIMER2 configuration for details.
    nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
    timer_cfg.frequency = NRF_TIMER_FREQ_31250Hz;
    
    ret_code_t err_code = nrf_drv_timer_init(&m_timer4, &timer_cfg, NULL);
    error_check(err_code);

    //compare 1
    nrf_drv_timer_extended_compare(&m_timer4,
                                   NRF_TIMER_CC_CHANNEL0,
                                   nrf_drv_timer_ms_to_ticks(&m_timer4, 15),  //15mS
                                   NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK,
                                   false);

    //compare 2
    nrf_drv_timer_extended_compare(&m_timer4,
                                   NRF_TIMER_CC_CHANNEL1,
                                   nrf_drv_timer_ms_to_ticks(&m_timer4, 5),  //5mS
                                   NRF_TIMER_SHORT_COMPARE1_CLEAR_MASK,
                                   false);
}