====== ARM Timer/Counter ======

===== Discussion on frequency measurements and frequency counts =====

{{https://www.pjrc.com/teensy/td_libs_FreqCount_vs_FreqMeasure.png?600}}

Source: Paul Stoffregen, [[https://www.pjrc.com/teensy/td_libs_FreqMeasure.html#compare|FreqCount vs FreqMeasure]]

Paul Stoffregen's libraries for Teensy and "standard" Arduinos (not M0):
  * FreqCount Library: 
    * About: https://www.pjrc.com/teensy/td_libs_FreqCount.html
    * Github: https://github.com/PaulStoffregen/FreqCount
  * FreqMeasure Library: 
    * About: https://www.pjrc.com/teensy/td_libs_FreqMeasure.html
    * Github: https://github.com/PaulStoffregen/FreqMeasure


===== ARM vs. AVR Timer =====

A good introduction on timer interrupts of AVR MCs is given by Amanda Ghassaei on Instructables: http://www.instructables.com/id/Arduino-Timer-Interrupts/ 

The configuration of timers in ARM cortex M processors such as SAMD21 is somewhat more complex. The links below may help to understand the timer/counter configurations.


===== Links =====

  * Paul Stoffregen (Teensy, Freescale)
    * **FreqCount Library:**
      * About: https://www.pjrc.com/teensy/td_libs_FreqCount.html
      * Github: https://github.com/PaulStoffregen/FreqCount
    * **FreqMeasure Library:** 
      * About: https://www.pjrc.com/teensy/td_libs_FreqMeasure.html
      * Github: https://github.com/PaulStoffregen/FreqMeasure


  * Max Bader (M0, zero): https://github.com/maxbader/arduino_tools
    * timer_m0_tc_counter
    * timer_m0_tc_interrupt
    * timer_m0_tcc_interrupt

  * Nonsintetic (M0, zero): https://gist.github.com/nonsintetic/
    * ArduinoZeroTimer

  * Arduino Forum: [[https://forum.arduino.cc/index.php?topic=332275.0|Arduino ZERO Timer Interrupts]]