What Is Interrupt Sevice Routine or Interrupt Handler Interrupt?

An interrupt service routine (ISR) or interrupt handle is a piece of code that code that should be executed when an interrupt is triggered. usually each enabled interrupt has it own ISR. in AVR assemble language each ISR must end with the RETI instruction which indicates the end of the ISR.

Interrupt can be categorized into Mask-able interrupt,non-mask-able interrupt,inter-processor interrupt(IPI),software interrupt, and superiors interrupt.

1.Maskable interrupt is a hardware interrupt that may be ignored by setting a bit in an interrupt mask register's bit-mask.

2. Non-mask-able interrupt is a hardware interrupt that locks an associate bit-mask , sot that it can never be ignored Non-mask-able interrupt are often used for timers ,specially watchdog timers.

3. Inter-processor interrupt(IPI) is a special case of interrupt that is generated by one processor to interrupt another processor in a multiprocessor system.

4. software interrupt is an interrupt generated within processor by executing an instruction.

5.spurious interrupt is a hardware interrupt that is unwanted. they are typically generated by system conditions such as electrical interference.