How to count pulses with interrupt in Arduino?

How to count pulses with interrupt in Arduino?

When the signal is present the output will go high. My attempt was to move the attach interrupt down into void loop, so it would repeat. Here’s what it looks like. The return I get is self-updating, but the “count” instead of starting from 0 each time starts from the previous count. So it gets larger and larger.

What does it mean when the interrupt fire multiple times?

As far as it firing multiple times, are you aware that you have the interrupt mode set to CHANGE? This means the interrupt will fire once when something enters the beam, and again when something leaves the beam. You will probably want to set it to RISING or FALLING so that it only fires on one of those events, not both.

How many interrupts can be fired on a photo interrupter?

The issue is that there can be several interrupts fired for each time the “beam” of the Photo Interrupter is broken. I have a 5mm length of plastic which breaks the “beam”.

When to disable interrupt in Arduino Stack Exchange?

Since an int is 2 bytes an interrupt might occur in the middle of setting/reading those two bytes. This might result in an occasional wrong value. To prevent that you should disable interrupt while setting/reading the value Highly active question. Earn 10 reputation (not counting the association bonus) in order to answer this question.

When to reset an INT after an interrupt?

I would actually keep the interrupt attached and just reset the variable just before the delay. That way the overhead of attach/detachinterrupt doesn’t get added to the 25ms delay. Since an int is 2 bytes an interrupt might occur in the middle of setting/reading those two bytes. This might result in an occasional wrong value.

Do you reset irqcount before attaching an interrupt?

You need to reset IRQCount back to 0 before attaching the interrupt again. Otherwise it will just continue counting from where it stopped last time. I would actually keep the interrupt attached and just reset the variable just before the delay.



What happens when signal drops out in Arduino Stack Exchange?

That way if the signal drops out I can trigger an output to turn off (LOW). When the signal is present the output will go high. My attempt was to move the attach interrupt down into void loop, so it would repeat. Here’s what it looks like.

Is the Arduino fast enough to respond to interrupts?

The Arduino is fast enough to respond to each of the interrupts caused by this bouncing, even though you can’t see it on the LED. Like Jon says the LEDs don’t have current limiting resistors; the red one is connected directly between +5 V and ground, and the blue one between the I/O pin and ground.

What is the serial number on the Arduino?

When the Arduino is reset it prints 315 to the serial over a 25 ms sample. 315 x 40 = 12600. Which seems to me it’s working perfectly. My only problem is it only returns this number once upon reset of the board.