Suggestion: custom getClock() function to allow removing reliance on micros() #53

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1. Dlloydev commented on Jul 1, 2022

   

   Dlloydev

   on Jul 1, 2022

   Owner

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   Thanks for your interesting suggestion!

   I do have an Arduino Every (somewhere) and didn't realize that it has an RTC. I'm extremely busy this summer, but sometime later this year, this would be something I'd like to try and implement. Also looks like the ESP32 dev boards have RTC, so I've got some learning and experimentation to do as I haven't yet worked with the RTC.

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2. ptashek commented on Jul 1, 2022

   

   ptashek

   on Jul 1, 2022

   Last edited by ptashek

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   While the 32k internal oscillator isn't great on the Atmega4809 it should be good enough for this use case.
   Probably the quickest way to start would be something like below. This gives a 1ms resolution, with a period of 32 clock cycles. Maximum resolution would be around 30 microseconds.

   volatile uint32_t pitCounter = 0;
   
   void RTC_init() {
     // Enable  internal 32k oscillator
     _PROTECTED_WRITE(CLKCTRL.OSC32KCTRLA, CLKCTRL_ENABLE_bm);
     // Wait for RTC synchronization
     while (RTC.STATUS > 0) {
       ;
     }
     // Enable RTC and set clock prescaler
     RTC.CTRLA |= RTC_PRESCALER_DIV1_gc | RTC_RTCEN_bm;
     // Set RTC to use internal 32k oscillator
     RTC.CLKSEL = RTC_CLKSEL_INT32K_gc;
     // Wait for PIT synchronization
     while (RTC.PITSTATUS > 0) {
       ;
     }
     // Set periodic interrupt period
     RTC.PITCTRLA |= RTC_PERIOD_CYC32_gc | RTC_PITEN_bm;
     // Enable periodic interrupt (used as clock)
     RTC.PITINTCTRL = RTC_PI_bm;
   }
   
   // RTC periodic interrupt handler (clock)
   ISR(RTC_PIT_vect) {
     RTC.PITINTFLAGS = RTC_PI_bm;
     pitCounter++;
   }
   

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3. Repository owner locked and limited conversation to collaborators on Jan 6, 2023
4. Dlloydev

   converted this issue into a discussion #59 on Jan 6, 2023