TMS320F28379D: Shadow Registers CMPA and TBPRD don´t work

Jens H

Hello,

I´ve got a problem with the shadow registers in the ePWM Module. I´ve configured them, that CMPA-Register, TBPRD-Register and AQCTLA-Register are loaded on TBCTR=ZRO. I write them once every Period.

I observed the registers in debugging mode and noticed that the shadow registers aren´t used. The values are directly written to the active registers.

This is how I configured the shadow registers:

    EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;    // Load registers every ZERO
    EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
    EPwm2Regs.TBCTL.bit.PRDLD = 0;
    EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
    EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
    EPwm2Regs.AQCTL.bit.SHDWAQAMODE = 1;
    EPwm2Regs.AQCTL.bit.LDAQAMODE = 0;
    EPwm2Regs.AQCTL.bit.LDAQASYNC = 0;

Usually the shadow registers should be used and loaded into the active registers on TBCTR=ZRO, right?

I hope you can help me with my problem.

Best Regards,

Jens

over 5 years ago

0 Nima Eskandari over 5 years ago

TI__Guru 52040 points

The shadow is being used. You wont see the internal shadow copy. When you write to the register, the debug window will show the value you last wrote. The internal shadow copy will get updated at the EVENT you selected.

0 Jens H over 5 years ago in reply to Nima Eskandari

Prodigy 130 points

Hello,

I'm pretty sure the shadow registers are not used. In debug mode the CMPA-Register is updated as soon as I write it. The SHDWAFULL bit is not set either.

Best Regards,

Jens

0 Nima Eskandari over 5 years ago in reply to Jens H

TI__Guru 52040 points

The outward facing register you see in the debug window IS the SHADOW register.

0 Jens H over 5 years ago in reply to Nima Eskandari

Prodigy 130 points

But shouldn´t the SHDWAFULL-bit be set after a write to the Shadow Register? SHDWAFULL is 0 the whole time in my application, but if the Shadow Registers are being used it should be 1 after a write and reseted to 0 after the loading event occured. Right?

Best Regards,

Jens

0 Nima Eskandari over 5 years ago in reply to Jens H

TI__Guru 52040 points

Yes that is correct, set the emulation mode of the EPWM module to FREEZE when the debugger halts the device, then put an ESTOP0 after writing to the registers to see the status of the shadows.

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TMS320F28379D: Shadow Registers CMPA and TBPRD don´t work