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Hello everyone,
I am using the PGA400 from Texas Instruments (an 8051W processor) with uVision V4.02 and have traced an issue back to using a switch statement in the commBuff ISR. It appears to either have corrupted or overflowed some sort of variable (this might not be the case but that's what it appears to have done). I've replaced it from:
switch (CommandState) { case (0): // random code here break; }
to:
if(CommandState==0) { // random code here }
This seems to have fixed my problem for whatever reason. Is it a common practice to avoid using switch statements in an ISR or is this a Keil related issue? Any help you can give me would be appreciated. Thanks a lot!
"We try to keep the ISR code as small as possible."
While that is, indeed, the usual recommendation for ISRs, it has nothing specifically to do with the use (or otherwise) of the 'switch' statement!
Note that it's the time within the ISR that's important - not the "size" of the code. So it doesn't matter how "large" the overall switch statement is - it's the time taken by the longest case which matters.