Yesterday I accidentely put my battery in the wrong way -> some diode blew up. It seemed that my Arduino still worked. Everything went fine until I tested some code to read PWM inputs, which involves interrupts, now every 5 seconds or so the programm freezes for a second until it goes back to normal. (The sketch worked fine a few days ago)
So is it possible that only some part of the board got fried, if so can i fix it somehow.
Are you using version 1.6.8 of the IDE, on windows, with serial monitor NOT open? In that circumstance, a bug in 1.6.8 will constantly poll the serial port causing the board to reset every few seconds - If this impacts you, I recommend using 1.6.5r5.
If it's not some spurrious thing like that, I would investigate whether you are still getting the right voltage on the 5v pin (that's where damage from connecting power backwards would show up).
Alternately, could there be a problem with your wiring?
In terms of damage to the chip, if it's the socketed one, you can just remove it and put in a new atmega328p (you need one with optiboot pre-installed). If it's the SMD one, which is much harder to replace at home. However, what you describe doesn't sound like typical failure mode for damaged microcontroller, the normal failure mode is blown pins.
Does anything feel warm or hot to the touch on the board?
Which diode blew up?
I never updated to 1.6.8 so I dont think thats the problem.
Maybe I should explain the problem better:
The problem only occurs when im using attachInterrupt on pin 2 & 3. If I'm just for example printing a string to serial everything is fine.
I put a diode between the battery + and vin, so nothing on the arduino itself. The chip doesnt get hot as far I can tell.
Anyways thanks for the help.