Can an interupt service routines use NON-global variables?

[treitmey]

My questions is, in general, is there a way to pass parameters into/out of the interupt service routines?

or do I always need to use global variables, when the scope needs to be in main().

[PCM programmer]

Yes, you should use global variables.
The reason is that an isr is "called" by a hardware event.
You don't call it with code, as you do a normal function.

[libor]

Regarding your question in the subject: You can declare and use local variables in an ISR, you can also use static variables that preserve their values between the interrupts, but these will be out of scope for the code outside if the ISR. For passing parameters into the ISR you have to use global variables, for passing data out of the ISR beside using global variables you can also call a function from the ISR with parameters.

[treitmey]

Thanks for the info.

I was trying to find a way pass a pointer to my buffer position
into the ISR. Global vars seem the only way to go, since I need the scope both inside the ISR and in main().

[Mark]

You can also use a function to return a value. But this will add extra time in the isr.

ptr = getBuffer();

[asmallri]