NRF52840 Timer channels with different periods.

Question

Hi There, 
 
 I have been looking for ways to have three channels of a hardware timer with the NRF52840 generate a compare interrupt at different time intervals, my understanding is that this is their functionality however I have not been able to implement it correctly. 
 For instance I want to get the following chain of events: 
 0----200us------300us-------1000us (Not necessarily these values). 
 -----CH0-------CH1---------CH2 (Timer interrupt events). 
 I have tried this: 
 
 nrfx_timer_compare(&timer,
 NRF_TIMER_CC_CHANNEL0,
 ticksToUs,
 true);
 nrfx_timer_compare(&timer,
 NRF_TIMER_CC_CHANNEL1,
 ticksToUsOne,
 true);
 nrfx_timer_compare(&timer,
 NRF_TIMER_CC_CHANNEL2,
 ticksToUsTwo,
 true); 
 
 And I do get the interrupts to occur for every channel at the given interval but they only occur once. How could I make this sequence periodic ? 
 What would be the best way tp implement this ? 
 
 Thanks, 
 
 Cheers

Sigurd · Accepted Answer

Hi, 
 When you get the last interrupt, call nrfx_timer_clear(), the timer will then 'restart' from the begin, 
 Alternatively , when you set up the last compare interrupt, use the function nrfx_timer_extended_compare() with a 'short mask' between the compare and the clear timer task 
 nrfx_timer_extended_compare(&timer,
NRF_TIMER_CC_CHANNEL2,
nrfx_timer_ms_to_ticks(&timer, delay_ms),
NRF_TIMER_SHORT_COMPARE2_CLEAR_MASK, //Shortcut for clearing the timer based on compare 2.
true);

NRF52840 Timer channels with different periods.

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