TMS320F280049: LIN_disableSCIInterrupt() bug in F28004x Support Library?

Wolfgang R.

Part Number: TMS320F280049
Other Parts Discussed in Thread: C2000WARE

referring to F28004x Support Library v1.11.00.00 or C2000Ware_MotorControl_SDK_4_00_00_00

In c2000ware/driverlib/f28004x/driverlib/lin.h the function LIN_disableSCIInterrupt() contains the following line:

HWREG_BP(base + LIN_O_SCICLEARINT) |= intFlags;

The read-modify-write will first read the current state (1 means enabled). Writing 1 to any bit then disables the associated interrupt.
So this function disables all enabled interrupts, not only the ones specified by intFlags as supposed.

It should be:

HWREG_BP(base + LIN_O_SCICLEARINT) = intFlags;

Similarly for LIN_enableSCIInterrupt(), but here it just re-enables already enabled interrupts.

over 2 years ago

0 Wolfgang R. over 2 years ago

Intellectual 356 points

after posting found this unresolved identical question:

https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/1005037/tms320f280025-lin_disablesciinterrupt

0 Vince over 2 years ago in reply to Wolfgang R.

TI__Mastermind 19795 points

Hi ReWolfgang,

Thanks for your question. I may not be understanding your question properly, but the LIN_disableSCIInterrupt() function seems to be written with the correct behavior. If you want to clear certain interrupts, then using "|= intFlags" should clear the flags specified by intFlags and nothing else. Writing a 0 has no effect so "|=" vs "=" has no difference:

Regards,

Vince

0 Wolfgang R. over 2 years ago in reply to Vince

Intellectual 356 points

Reading the SCICLEARINT register returns the current enable-state of the interrupts: enabled interrupts read as "1".

So any enabled interrupt will be disabled if |= is used because "1" will be read and then written to enabled interrupts.

0 Vince over 2 years ago in reply to Wolfgang R.

TI__Mastermind 19795 points

Hi ReWolfgang,

Thanks for the clarification, I missed the fact that this is a clear-on-1 register (not just a write-0-has-no-affect register). I've passed this along to the software experts who will test and implement a fix by next release.

Regards,

Vince

0 Wolfgang R. over 2 years ago in reply to Vince

Intellectual 356 points

BTW: LIN_clearInterruptStatus() and LIN_clearSCIInterruptStatus() could have the same problem:
they also use |= to clear selected status bits on a clear-on-1-register, so they clear ALL bits reading as 1, not only the selected ones.