====== Interrupts ======

===== Lecture Material =====
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This lecture is related to interrupts \\ of the AVR **[[rtes:topics:arduino:ATmega328|ATmega328]]** microcontroller.
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We use part of the excellent material from [[http://courses.cs.washington.edu/courses/csep567/10wi/|"CSE P567, Design and Implementation of Digital Systems (Winter 2010)"]] by Carl Ebeling, Computer Science and Engineering Program, University of Washington 
/*
  * Lecture 6: {{:envmon:ws2015:session_03:lecture6_atmega328_arduino.pdf|Introduction to the ATmega328 and Arduino}}
  * Lecture 7: {{:envmon:ws2015:session_03:lecture7_timers_interrupts.pdf|ATmega328 Timers and Interrupts}}
*/
  * Lecture 6: {{ :rtes:topics:arduino:lecture6_atmega328_arduino.pdf |}}
  * Lecture 7: {{ :rtes:topics:arduino:lecture7_timers_interrupts.pdf |}}

  *  [[https://www.microchip.com/wwwproducts/en/ATmega328p|ATmega328P web page]]
  * {{http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega328_P%20AVR%20MCU%20with%20picoPower%20Technology%20Data%20Sheet%2040001984A.pdf|ATmega328P Datasheet (pdf)}}
  * {{http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-42735-8-bit-AVR-Microcontroller-ATmega328-328P_Summary.pdf|ATmega328P Datasheet Summary (pdf)}}

From the introduction to ATmege328 ("Lecture 6") we just need:
  * AVR register file: some discussions
  * AVR memory
  * Interrupts
  * I/O ports, pin circuitry

We don't need:
  * Addressing modes
  * Instructions

==== Interrupt and Context Switch ====

A very good explanation is found here:
  * https://www.quora.com/What-is-the-difference-between-context-switching-and-interrupt-handling
 
===== Lab / Exercises / Homework =====

==== 1) Time Interrupts ====

Let us work on Arduino Timer Interrupts based on material from instructables \\ http://www.instructables.com/id/Arduino-Timer-Interrupts/?ALLSTEPS 


==== 2) Generate f = 3 kHz ====

Modify the code from the instructable above to generate a frequency of f = 3 kHz.

==== The Lazy Ones use this ====

http://www.8bit-era.cz/arduino-timer-interrupts-calculator.html

===== Links =====

  * https://oscarliang.com/arduino-timer-and-interrupt-tutorial/
  * http://ucexperiment.wordpress.com/2012/03/16/examination-of-the-arduino-millis-function/
  * https://arduinodiy.wordpress.com/2012/02/28/timer-interrupts/
  * [[http://www.atmel.com/Images/doc2505.pdf|AVR130: Setup and Use the AVR® Timers]] (pdf)
  * https://sites.google.com/site/qeewiki/books/avr-guide/timers-on-the-atmega328