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1. 

   dezulm
   Member

   I have an external interrupt that kick offs when a pin change occurs. In the the handler, I do timer1.getCount to determine the period and pulse width. The signal that I have as input is 1 kHZ 50% duty cycle. I set up the timer in the setup() as follows:
   

   // ...
       timer1.setChannel1Mode(TIMER_OUTPUT_COMPARE);
       timer1.pause();
       timer1.setCount(0);
       timer1.setPrescaleFactor(72);  //run at 72 MHz/72 = 1MHz count every 1us
       timer1.setOverflow(65535);
       timer1.setCompare1(1);
       timer1.attachCompare1Interrupt(timer1_handler);
       timer1.refresh();
       timer1.resume();
   
   Sample handler code:
   
   void exti_handler()
   {
       timer1.pause();
       CurrentCount = timer1.getCount();
       val = digitalRead(0);
   
       if (val == HIGH)
       {
           LowToHighCount++;
           Period = CurrentCount;
           timer1.setCount(0);
           timer1.refresh();
       }
       else { // state must be LOW
           HighToLowCount++;
           PulseWidth = CurrentCount;
       }
   
       timer1.resume();
   }

   timer interrupt is just adding up a timercounter which does nothing

   Any guidance or thoughts?

   Posted 3 years ago #
2. 

   gbulmer
   Moderator

   dezulm - I took the liberty of formatting your code, to make it easier for me to read. I hope that is okay.

   I don't think I understand what is happening or not happening. Would you please explain?

   Maybe you could paste all the code at pastebin or somewhere?

   Is timer1_handler getting called?
   Is exti_handler getting called?

   (You could test these by flipping a pin in the handler, and observing the pin or pins with your oscilloscope)

   (Full disclosure: I am not a member of LeafLabs staff)

   Posted 3 years ago #
3. 

   dezulm
   Member

   I have included the code in the pastebin. The external interrupt handler gets called. The timer interrupt does not do anything. The pulse width and period values are completely off. I had another version where I just use micros() and that one also had bad values for period and pulse width. I am injecting a 1khz 50% duty cycle PWM on pin 0 (3.2 V amplitude and dc offset of 1.6). I want to see if the period and pulse width counts being displayed reflect 1000 us and 500 us for pulse width.

   http://pastebin.com/FK6gXYKk

   Posted 3 years ago #
4. 

   dezulm
   Member

   It seems that signal from function generator is not working. Although looks great on scope it being read correctly. I generated a signal on the board and jumpered. This works.

   Posted 3 years ago #

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