SPC58NH FPU exception

[Michal Polrola]

Hi all,

I'm trying add FPU exception to my project and I'm bit confused because two sources points two different interrupt vectors for this. Book E says, FPU exception is under IVOR33 but SPC58xH manual points IVOR10. And SPC5Studio libraries have "decrementer support" under IVOR10. I suspect SPC58xH is right for me but I want to be sure. 

regards

Michal

[Erwan YVIN]

Hello , 

i am checking the mismatch between booke and SPC58Hx Ref Manual

by default , take Chorus_10M Reference Manual 😉

           Best regards

                       Erwan

[Michal Polrola]

Hi Erwan,

I've found bug in application note AN5549 where figures 6 and 10 should be swapped. 

Hardware vector mode require vector table at offset 0x1000 so fig. 10 is incorrect.

regards

Michal

[Giuseppe DI-GIORE · Accepted solution]

Hello,

SPC58xH Reference Manual is right.

SPC58xH implements two FPU exceptions:

• EFPU Data Exception (offset 0xA0)
• EFPU Round Exception (offset 0xB0)

Each entry in the exception table is 16 bytes.

Considering the exception table as an array with 16 bytes for each entry:

• offset 0xA0 is at index 10 (decimal): IVOR10
• offset 0xB0 is at index 11 (decimal): IVOR11 

In SPC5Studio, exception table implementation uses align 4 directive to have 16 bytes displacement.

SPC5Studio implements the exception table up to entry 15 (IVOR15)

IVOR10 implementation, in SPC5Studio, refers to the decrementer as defined on Book-E but the code is commented, just a matter of porting the exception handlers form a previous device (which implements the decrementer at IVOR10).

Best Regards.

[Michal Polrola]

Is it necessary switch to hardware vector mode to support FPU exception in IVOR10?

regards

Michal

[Giuseppe DI-GIORE]

Hello Michal,

there is no need to switch to hardware mode interrupt to handle IVOR10 exception.

Please have a look at SPC58NH Reference Manual rev4, at page 450.

Regards,