Electronic – MSP430 how to make configurable ISRs in a module (Code composer studio C)

cinterruptsisrmicrocontrollermsp430

I have a question that I think the answer to is quite simple. But I've been unable to find a straight answer to.

If i have this service routine in some module foo.c

#pragma vector = SOME_VECTOR
interrupt void fooISR(){
    dosomething;
    IFG = 0;
}

if i have in my main.

#include "foo.h"

Then it appears that the fooISR() does indeed get loaded into the SOME_VECTOR and the ISR will trigger whenever the corresponding IFG is set.

I wanted to ask if this is the right way to write modules that utilize interrupts. Because with this approach the fooISR() will be in the SOME_VECTOR whenever I include foo.h this doesn't really allow for much configuration for the person working in main.

For example if in main.c I wanted to access some functionality of foo.c but wanted to write a separate ISR for SOME_VECTOR I'd be outta luck with this method right?

Best Answer

The concern that you express in the last paragraph is correct. It doesn't seem to be a good idea to bundle an ISR with other functionality that you might want to reuse separately from the ISR.

I usually do one of the 3 things:

Put the ISRs and main into the same file as main(). ISRs are short, so they don't clutter the main.c too much.
Put all ISRs together into a separate module. No other functionality in that module. No intention to make this ISRs module reusable.
Put each ISR into its own module. No other functionality in those modules.

You could put the ISR inside of an #ifdef block, if it makes sense in your particular situation.

Related Solutions

Electronic – Code Composer Studio v4 and MSP430 development

I just got one of those $4.30 MSP-EXP430G2 boards, and, having worked with both Eclipse and CCSv3 (the full license version), I also downloaded CCSv4, thinking that would be the path with the easiest learning curve.

There may be some kind of tutorial on the MSP430 launchpad wiki, but I haven't found it yet. Ideally there should be a how-to that shows, starting from scratch, how to create a project and get it into the device. If I do find such a thing, I'll edit this post to try to include the correct link.

Electronic – Interrupt Service Routine in C – function at specific address

You'll find the information you need in the compiler's manual: MPLAB C18 C COMPILER USER'S GUIDE.

From page 37 of the user's guide:

MPLAB C18 does not automatically place an ISR at the interrupt vector. Commonly, a GOTO instruction is placed at the interrupt vector for transferring control to the ISR proper. For example:

void lowPriorityISR(void);

#pragma code low_vector=0x18
void interrupt_at_low_vector(void) { 
    _asm GOTO lowPriorityISR _endasm 
}
#pragma code

#pragma interruptlow lowPriorityISR
void lowPriorityISR() {
}

When implementing a high priority ISR, you cannot use the interrupthigh pragma as you would expect. You'll have to use the interrupt pragma instead, as is described here.

If you can change the compiler: using interrupts is easier in the Microchip XC8 or HI-TECH PICC compilers.

Best Answer

Related Solutions

Electronic – Code Composer Studio v4 and MSP430 development

Electronic – Interrupt Service Routine in C – function at specific address

Related Topic