TMS320F28374s: Cause of FPU overflow/underflow Interrupt and how to located the which instruction caused the interrupt

Hi Benjamin,

One way to get this is to take it from the stack. If you set a break-point at the top of the ISR and look at the SP register, you should be able to go down the stack a few addresses and find the return program address which was pushed when the interrupt was taken. It should be 14 words (i.e. 7 x 32-bit words) down from SP, but depending on your code and compiler settings your ISR may have pushed other data onto the stack before you hit the break-point, so it might be 16 or more words down.

Open a memory browser to view the stack memory and count back from SP. You should see a feasible address there, then locate the code line in the disassembly window.

Regards,

Richard

Hi Richard,

  Update the customer's feedback, could you kindly help to point out which value should be the right value to located the cause of FPU interrupt?

Thanks a lot.

Best Regards

BenjaminFPU SP Stack _From Customer.docx

Benjamin,

I don't see the interrupt break-point.  Did he write a separate ISR and just place a BP inside?  If not, the compiler may push other stuff on the stack so the return address is going to be further down, as I said.  

Open a dis-assembly window to see what's being pushed in the ISR.  The return address should be 7 32-bit words down, plus that number of pushes.  Based on your screen-shot I'd say the likely return address is either 0xC010 or 0x9 87C2.  

BTW, it's a lot easier to see the addresses if you set the memory browser window to display the stack as 32-bit hex values.

Regards,

Richard

Richard,
Very appreciated for your kindly support.
Seems the customer used the solution you provided which help to find the right PC pointer.

Best Regards
Benjamin

Benjamin,

Glad the post was helpful. Thank you for letting me know.

Regards,

Richard