Frequency counter on NRF52805

[matangk]

Hi, I want to use an NRF52805 with a voltage to frequency detector. If I understand the datasheet, there is one timer/counter and RTC on that chip. Is it possible to set the RTC as the timing gate, and  use the T/C as an input pulse counter through the event system? I'm planning to use a single clock source (prob. 32MHz) and synthesize the LF clock required for the RTC from it.

I will be happy to know if this is a good way to go before fully adopting the hardware.

Cheers,

[Simonr]

Hi

Indeed, the nRF52805 has 3 32-bit timers with counter mode and 2 RTCs available. If you see section 4.2.4 Instantiation in the product specification you can see what base addresses they use, so there should be no issues using two timers in your application.

Best regards,

Simon

[matangk]

OK, a few days with an NRF52-DK at hand I have a few more questions:

1. I see that there is a guy who did implement a counter similarly to what I want, using 2xtimers, events, tasks, and ppi here. I'm not 100% OK with the solution since: (a) the tasks of the counter and timer are both started from main. This does not guarantee a consistent timing for the counter and gate functions. (b) Likewise counter is read from a timer interrupt.

2. What i'd like to do is as follows: (a) Clear Timer0 -> (b) on Timer0 start generate event to start Counter1 -> (c) On Timer0 CC generate event to stop counter -> (d) on stop Counter1 generate event to stop Timer0

3. Can this be done? i.e. can I generate an event on Timer0 start and link it to Counter1 start? Also, can (d) be done? I have nothing against generating events (c) and (d) together from Timer0 CC with FORK if its easier.

4. I noticed that the ppi example that I attached above can't locate the required ENUMs, unless I add #include<hal/nrf_gpiote.h>. Should I use this piece of code? I am using VS code on NRF connect and had problems utilyzing the ADC when I inclused <hal/nrf_saadc.h>. If not, is there a good PPI/EVENT example for nrf connect?

Any help will be appreciated!

Matan