Re: Differences between interrupt service routine (ISR) and a subroutine

"2005" <uws2003@xxxxxxxxx> wrote in message
news:1164736936.337323.40270@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi

This is another homework question isn't it?

What are the differences between ISR and a subroutine in embedded
systems, how about the following:
- interrupts are disabled by the microprocessor prior to calling the
isr

Not always - google for nested interrupts.

- isr's are always smaller

Not necessarily. ISRs _should_ be kept small but that doesn't always
happen.

- an isr cannot be written in C

Not true but when written in C you normally need an attribute to tell
the compiler that the function is to be an ISR.

- a subroutine always has arguments

Not true. void Subroutine(void); is a perfectly acceptable prototype.

- the CPU flags are stored on the stack in addition to the return
address

That is true (although I suspect some pedants will find an example of
systems that don't).



.

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