1. Can someone give me a reference that explains in detail how the timer interrupt works? In particular what all of the different flags and registers do? I'm using things like TIMSK2 and CCS21 for example but don't have any sort of reference for them and so don't know what they do are what they mean.2. How many timer interrupts are available and how does one use more than one of them?3. Do I have to disable anything in the arduino code in order to avoid conflicts? I am not using pwm at all.4. Can I use timer interrupts and external interrupts at the same time?