TCCR2B |= (1 << CS22) // Set CS#2 bit for 64 prescaler for timer 2 This follows directly from the datasheet of the ATMEL 328/168.įinally, notice how the setup for the prescalers follows the tables in the last step (the table for timer 0 is repeated above), Remember that when you use timers 0 and 2 this number must be less than 256, and less than 65536 for timer1Īlso notice how the setups between the three timers differ slightly in the line which turns on CTC mode: As explained in the last step, this was calculated according to the following equation:Ĭompare match register = - 1 Notice how the value of OCR#A (the compare match value) changes for each of these timer setups.
set compare match register for 8khz increments TCNT2 = 0 //initialize counter value to 0 TCCR2A = 0 // set entire TCCR2A register to 0 Set CS10 and CS12 bits for 1024 prescaler set compare match register for 1hz increments TCNT1 = 0 //initialize counter value to 0 TCCR1A = 0 // set entire TCCR1A register to 0 Set CS01 and CS00 bits for 64 prescaler set compare match register for 2khz increments
TCNT0 = 0 //initialize counter value to 0 TCCR0A = 0 // set entire TCCR0A register to 0 The main structure of the interrupt setup looks like this:
#Arduino timer interrupt setup code
I pretty much just copy the same main chunk of code and change the prescaler and compare match register to set the correct interrupt frequency. The code involved for setting up timer interrupts is a little daunting to look at, but it's actually not that hard. Normally when you write an Arduino sketch the Arduino performs all the commands encapsulated in the loop() function in an Arduino sketch. Jump straight to step 2 if you are looking for sample code.
#Arduino timer interrupt setup how to
In this instructable I'll explain how to setup and execute an interrupt in Clear Timer on Compare Match or CTC Mode. Timer interrupts allow you to perform a task at very specifically timed intervals regardless of what else is going on in your code.
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