How is ISR a callback function

microcontroller interrupt-handling isr
RootPhoenix picture RootPhoenix · Aug 2, 2014 · Viewed 7.1k times · Source

The wikipedia entry states:

In computer system programming, an interrupt handler, also known as an interrupt service routine or ISR, is a callback function in microcontroller firmware, an operating system or a device driver, whose execution is triggered by the reception of an interrupt.

How is ISR a callback. Is it the PC value stored on stack itself is the callback function?

I.e., the ISR calls the interrupted function back. Hence the interrupted function is a callback.

Answer

Boann picture Boann · Aug 2, 2014

A bit of setup code stores the address of the ISR function in the interrupt vector table to say "call me back at this address when the interrupt occurs".

To be clear, the ISR itself is the function that is "called back". The interrupted code is not the callback; it is merely "interrupted" and later "resumed".

Related questions

Do interrupts interrupt other interrupts on Arduino?

I have an Arduino Uno (awesome little device!). It has two interrupts; let's call them 0 and 1. I attach a handler to interrupt 0 and a different one to interrupt 1, using attachInterrupt() : http://www.arduino.cc/en/Reference/AttachInterrupt. Interrupt 0 is triggered …

Read More
What is the difference between baud rate and bit rate?

I am really having hard time understanding the difference. Some say they are same, while others say there is a slight difference. What's the difference, exactly? I would like it if you explained with some analogy.

Read More
How to convert Char into Float

How to convert an unsigned char value into a float or double in coding in AVR studio 4.? Please help I am a beginner, my question may sound stupid too :/ Like I have got a char keyPressed and I have printed …

Read More