So, tonight’s presentation is on interrupts on the Arduino Uno. You will learn so much while collecting information, formulating your thoughts, and putting it on “paper”. I would encourage each of you to consider making a presentation, however short and simple. I would encourage each of you to consider making a presentation, however.'- Presentation transcript:ġ Arduino Interrupts I am amazed by how much I learned in preparing for this talk. The following script shows the Arduino code, that we discuss step by step.Presentation on theme: 'Arduino Interrupts I am amazed by how much I learned in preparing for this talk. Only the frequency when to interrupt has to be adjusted as well as the registers based on their maximal values. Therefore we are able to verify the behavior of the interrupt with the oscilloscope.īasically the structure is for all three interrupts the same. In this example we set the pin HIGH if there is no interrupt and LOW if there is an interrupt.

Define the functions ISR(TIMERx_COMPA_vect) to define what the Arduino should do when the interrupt has taken place.

With the function call sei() we allow interrupts during the run-time of the microcontroller.Set the value to which the counter value should be compared OCRxA to the following equation: (16*10^6) / (frequency*64) – 1.Initialize the counter value TCNTx to 0.Set the 2 registers TCCRxA and TCCRxB to zero.In the setup function we create the CTC interrupts.The third timeout at 8kHz toggles Arduino Uno pin 9.The second timeout at 1Hz toggles Arduino Uno pin 13.The first timeout at 2kHz toggles Arduino Uno pin 8.In the following example we want to create a sketch with three different interrupts based on the CTC mode: Therefore only Timer 1 is able to perform the task 15624<65535. Timer 0 and Timer 2 can not perform that task because their maximum value to store is 255 with 8bit. Now we have to choose the timer of that 1Hz second interruption. For the ATmega328 with the greatest prescaler of 1024, the value of the register would be: (16MHz / 1024 * 1Hz) -1 = 15624. We have to subtract 1 because the match register is zero indexed (depends on the microcontroller). If we want to interrupt every second, the value in the match register is = (clock speed / prescaler * interrupt frequency) -1.

TIFRx – Timer/Counter Interrupt Flag Register.TIMSKx – Timer/Counter Interrupt Mask Register.ICRx – Input Capture Register (only for 16bit timer).The most used timer registers are the following:

At the same time the timer is cleared and set to zero and restarts the counting. This value is stored in the compare match register. CTC timer interrupts are events which are triggered when the timer reaches a predefined value.

Arduino uno external interrupt example