Compiler/TMS320F280049C: blanking of pulses using trip zone

Reshma_M

Tool/software: TI C/C++ Compiler

Hi,

I was trying to blank pulses using trip zone (trip4, epwm1a alone). I used the following lines to achieve this.

EPwm1Regs.DCAHTRIPSEL.bit.TRIPINPUT4 = 1; //enabling tripinput4
EPwm1Regs.DCTRIPSEL.bit.DCAHCOMPSEL = 3; //selecting tripinput 4

//configuring trip zone for pfc
EPwm1Regs.TZCTL.bit.TZA = 2; //Force EPWMxA to a low state
EPwm1Regs.TZCTL.bit.DCAEVT2 = 2; //Force EPWMxA to a low state
EPwm1Regs.TZDCSEL.bit.DCAEVT2 = 2; //DCAH = high, DCAL = don't care

Now, I wanted to try the same with another epwm (along with the existing one), in which I want to blank both epwm2a and epwm2b when after certain voltage level is reached. For this I used trip5 and b4 pin as analog input. I used the following lines for this.

EPwm2Regs.DCTRIPSEL.bit.DCAHCOMPSEL = 4; //selecting trip5
EPwm2Regs.DCAHTRIPSEL.bit.TRIPINPUT5 = 1; //selecting trip5

EPwm2Regs.TZCTL.bit.TZA = 2; //force epwm2 to low
EPwm2Regs.TZCTL.bit.DCAEVT2 = 2; //force epwm2 to low
EPwm2Regs.TZDCSEL.bit.DCAEVT2 = 2; //DCAH = high, DCAL = don't care

But with this code, epwm2a is always blanked while epwm2b has pulses. No matter the input analog voltage, the same thing repeats. I observed that the same thing repeats with epwm2b when I change DCA to DCB. What I don't understand is why I did not encounter this in the first case?

Can someone help me out with this? Is there something I am missing?

And how will I be able to blank both the channels of epwm2 simultaneously with the same voltage level?

Regards,
Reshma

over 7 years ago

0 Nima Eskandari over 7 years ago

TI__Guru 52220 points

If you want both EPWMxA and xB to be tripped, you have to use both DCAEVT and DCBEVT. You cannot use one and expect both xA and xB to be tripped. Next, If you are using an analog signal, send it to CMPSS, set a threashold, use that output as the signal for the EPWMXBAR TripX and use that trip to be the source for DCAEVT and DCBEVT.

Thank you,

Nima Eskandari

0 Reshma_M over 7 years ago in reply to Nima Eskandari

Intellectual 290 points

I understand, but I'm trying to only blank the pulses when the analog signal sent via CMPSS crosses a certain threshold. This signal is further linked to the EPWMXBAR TripX and is then being used for the DCA activities.

I used the following code to blank both the xA and xB. But when this code is run, the signal is always low no matter what the threshold remains.

EPwm2Regs.DCTRIPSEL.bit.DCAHCOMPSEL = 4; //selecting trip5
EPwm2Regs.DCAHTRIPSEL.bit.TRIPINPUT5 = 1; //selecting trip5

EPwm2Regs.TZCTL.bit.TZA = 2; //force epwm2 to low
EPwm2Regs.TZCTL.bit.DCAEVT2 = 2; //force epwm2 to low
EPwm2Regs.TZDCSEL.bit.DCAEVT2 = 2; //DCAH = high, DCAL = don't care

EPwm2Regs.DCTRIPSEL.bit.DCBHCOMPSEL = 4; //selecting trip5
EPwm2Regs.DCBHTRIPSEL.bit.TRIPINPUT5 = 1; //selecting trip5

EPwm2Regs.TZCTL.bit.TZB = 2; //force epwm2 to low
EPwm2Regs.TZCTL.bit.DCBEVT2 = 2; //force epwm2 to low
EPwm2Regs.TZDCSEL.bit.DCBEVT2 = 2; //DCBH = high, DCBL = don't care

Please let me know what I can do about it.

Regards
Reshma