Ok with a bit of mucking about i managed to figure out how to get it too work. The other interrupts start to work if i change the input to a square wave, interrupt 2 seems to be the only one to work with the sine wave. Thats ok. i actually only need to read in 1 sine wave, and one square.
What is your hardware arrangement? You just can't feed a sin wave into an arduino
Im using a function generator to create the signal so its a pretty acurate sine wave. This also means the input current is low, so i dont need to
I'm not familiar with this, but isn't pin 21 a signal line for the TWI? Maybe that is interfering with what you're trying to do.
TWI? well its the only one working?
You don't seem to be initialising the pin mode or pull-up status for any of your inputs/outputs. I think explicitly initialising all the pins you use would make things more obvious.
Do i need to initialise the interrupt pins? in the example it didnt say i have to, and does pull-up status reffer to pull up resistors?
Thanks