Which instruction is used to end the interrupt service routine?

Which instruction is used to end the interrupt service routine?

RETI instruction
The RETI instruction is used to end an interrupt service routine. This instruction pops the high-order and low-order bytes of the PC (and decrements the stack pointer by 2) and restores the interrput logic to accept additional interrupts. No other registers are affected by this instruction.

How are interrupts handled?

The software assigns each interrupt to a handler in the interrupt table. An interrupt handler is just a routine containing a sequence of operations. Each of these may request input and output while running. Thus, an interrupt can be handled either as a thread or as a sub-process within a task or process.

What is interrupt service routine in Arduino?

interrupt : the number of the interrupt. Allowed data types: int . pin : the Arduino pin number. ISR : the ISR to call when the interrupt occurs; this function must take no parameters and return nothing. This function is sometimes referred to as an interrupt service routine.

How is an interrupt service routine similar to a C function?

Interrupt Service Routines in C are similar to C functions, except of course they are called by occurrence of an interrupt and terminate with a return from interrupt instruction. They can have local variables (i.e. variables declared within the ISR) and access global ones.

How is the background thread created in an interrupt service routine?

The execution of the interrupt service routine is called a background thread. This thread is created by the hardware interrupt request and is killed when the interrupt service routine returns from interrupt (e.g., by executing a BX LR ). A new thread is created for each interrupt request.

When to use a low level interrupt service routine?

The situation becomes more complex if the ISR makes an API call which affects the scheduler. This may result in the interrupt returning to a different task from the one that was running when the interrupt occurred. A low-level interrupt service routine (LISR) executes as a normal ISR, which includes using the current stack.

How does an interrupt service routine work without RTOS?

In a system implemented without an RTOS, this is simply a matter of preserving any registers used by the ISR—generally on the stack—and restoring them before return. Some processors have provision for a dedicated ISR stack—others simply use the same one as the application code.