#ARDUINO TIMER INTERRUPT DRIVEN LOOP HOW TO#
#ARDUINO TIMER INTERRUPT DRIVEN LOOP SOFTWARE#
#ARDUINO TIMER INTERRUPT DRIVEN LOOP CODE#

This uses the input-capture pin (ICP1) feature of timer1. The logic-level input must be on Arduino pin 8. Note that the subtract is correct even if the counter overflows (once) between readings.

There are various ways of timing intervals (and therefore frequency):īefore the Arduino initialization code, write an interrupt service routine to copy timer 1 into a register and subtract to get a period.

This feature allows the cpu to determine the exact time of an external event.

This allows the cpu to determine when an analog voltage equals an arbitrary reference voltage.

The event can be a change in state of a built-in analog comparator (timer1 only!).

The event can be a logic transition on one i/o pin.

Copy the value in the timer counter (current time) into an input capture register (ICR1) when an external event occurs.

In PWM mode, a timer cannot do anything else!.

An interrupt can be generated on every PWM cycle if enabled.

Two PWM signals for each timer are output to pins based on preset value (OCR1A or OCR1B) which can be changed on every PWM cycle.

#ARDUINO TIMER INTERRUPT DRIVEN LOOP SOFTWARE#

This feature can be used to generate square waves of aribtrary frequencies with no software overhead.

Reaching the preset value in OCR1A or OCR1B can cause an output pin to be set, cleared, or toggled.

Counting to a preset value, folllowed by reset (and automatic continued counting) is the best way to generate a precision time base.

Reaching the preset value in OCR1A can cause the timer to be reset.

Reaching any preset value can trigger interrupts if enabled.

Count to two preset values specified in Output Compare Register A or B (OCR1A, OCR1B).

Overflow may trigger an interrupt if enabled.

Count to 2^16-1, then roll over to zero and keep counting.Prescalar divides the cpu clock by: off, 1, 8, 64, 256, 1024. Timer1 can use a prescalar or increment based on input from an i/o pin (rising/falling edge).Timer1 is a 16 bit counter that can be set to perfrom several different functions.

#ARDUINO TIMER INTERRUPT DRIVEN LOOP HOW TO#

There is nothing about sending serial data that needs to happen IMMEDIATELY, when sending serial data is sssllloooSo, what is it, EXACTLY, that you are trying to accomplish? Do not repeat the lame 'check how to use arduino mega for interrupt based serial communication' statement, since sending and receiving serial data is already interrupt based.The Arduino environment uses the Mega328 timer0, but does not touch timer1. Interrupts are meant for things that must be dealt with immediately, like serial data arriving, the clock ticking, etc.

#ARDUINO TIMER INTERRUPT DRIVEN LOOP CODE#

While interrupts are disabled you use two functions that rely on interrupts, so that code is never going to work. Of course, you only do it at the end, when they would be re-enabled anyway, so doing it is pointless. That seems to exclude you, so you should not be enabling interrupts in the ISR. Where it is done, the person writing the code has a COMPLETE understanding of interrupt handling, interrupt priorities, and of the possible problems that will arise. Re-enabling interrupts in an ISR is not something that is typically done. In an ISR, interrupts are already disable, so the noInterrupts() call is useless.

Arduino timer interrupt driven loop