Contents
What count will be in the counter when the timer generates an interrupt?
Timer/counter will count up from the 16 bit value initially stored in TH0/1 and TL0/1 to 65535, and then Page 9 overflow back to 0. If an interrupt is enabled, an interrupt will occur upon overflow. If used as timer, pulses from the processor are only divided by 12. equals the oscillator frequency divided by 24.
What is the timer interrupt?
Timer interrupts allow you to perform a task at very specifically timed intervals regardless of what else is going on in your code. In this instructable I’ll explain how to setup and execute an interrupt in Clear Timer on Compare Match or CTC Mode.
What is the difference between a timer and a counter?
A timer is a specialized type of clock which is used to measure time intervals. A counter is a device that stores (and sometimes displays) the number of times a particular event or process occurred, with respect to a clock signal. It is used to count the events happening outside the microcontroller.
How to control the frequency of timer interrupts?
By choosing the compare match value and setting the speed at which the timer increments the counter, you can control the frequency of timer interrupts. The first parameter I’ll discuss is the speed at which the timer increments the counter.
When does a timer / counter ask for an interruption?
So, like any other peripheral, a Timer/Counter can ask for an interruption of the program, which – if enabled – occurs when the counting registers of the Timer/Counter are full and overflow. More precisely, the interruption will occur at the same time the counting register will be reinitialized to its initial value.
When does a CTC timer interrupt take place?
CTC timer interrupts are triggered when the counter reaches a specified value, stored in the compare match register. Once a timer counter reaches this value it will clear (reset to zero) on the next tick of the timer’s clock, then it will continue to count up to the compare match value again.
How often do interrupts occur on an Arduino?
Once a counter reaches its maximum, it will tick back to zero (this is called overflow). This means at 16MHz, even if we set the compare match register to the max counter value, interrupts will occur every 256/16,000,000 seconds (~16us) for the 8 bit counters, and every 65,536/16,000,000 (~4 ms) seconds for the 16 bit counter.