TMS320F28379D: Synchronize ePWM1 with external signal connected at GPIO18

Kshitij Rajesh Dachewar

Part Number: TMS320F28379D

Tool/software:

Hi,

I want to synchronize EPWM1A on external signal which I have given to GPIO18. But I am not able see synchronization between external signal and EPWM.

I am mapping GPIO18 to Inputxbar5 as below:

EALLOW;
InputXbarRegs.INPUT5SELECT = 0x12; // Map GPIO18 to INPUT5
GpioCtrlRegs.GPAMUX2.bit.GPIO18 = 0; // Set GPIO18 as GPIO
GpioCtrlRegs.GPADIR.bit.GPIO18 = 0; // configure as input
GpioCtrlRegs.GPAPUD.bit.GPIO18 = 0; // Disable pull-up
GpioCtrlRegs.GPAINV.bit.GPIO18 = 1; // Invert input
EDIS;

And I configuring EPWM1 in slave mode

EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; // Clock ratio to SYSCLKOUT
EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1;
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Count up/down and down
EPwm1Regs.TBPRD = PQAB_TBPRD; // Set timer period

EPwm1Regs.TBCTL.bit.PHSEN = TB_ENABLE; // SLAVE, Enable phase SYNC
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // Sync to external signal (GPIO18 I.E. SPICLK MAPPED TO INPUT5)
EPwm1Regs.TBPHS.bit.TBPHS = 0; // Phase is 0
EPwm1Regs.TBCTL.bit.PHSDIR = TB_UP;
EPwm1Regs.TBCTR = 0x0000; // Clear counter

9 months ago

0 Allison Nguyen 9 months ago

TI__Mastermind 24370 points

Hello,

Please refer to these similar threads first to see if they are able to resolve your inquiry.

Best Regards,

Allison

0 Kshitij Rajesh Dachewar 9 months ago in reply to Allison Nguyen

Prodigy 20 points

Thanks Allison.

Rising edge of the external signal is zero of the EPWM1 up-down carrier. From my code, the rising edge of PWM1 will be at CMPA. As a result, I am seeing delay between rising edge of external signal and rising edge of epwm1.

Is there any way I can sync the rising edges of EPWM1A with rising edge external signal with up-down carrier?

0 Allison Nguyen 9 months ago in reply to Kshitij Rajesh Dachewar

TI__Mastermind 24370 points

Hello,

If you want the rising edge of your EPWM to occur at/around the sync pulse, you need to set your TBPHS value equal to the value of your TBCTR that triggers your rising edge. So if you have a rising edge on CMPA, you need to set TBPHS equal to or before your CMPA value to see that rising edge occur right after a sync.

When a sync pulse is seen by the EPWM module, the EPWM's TBPHS value is loaded as the TBCTR value (and then the counter continues on counting from there). This functionality is also explained in our TRM in the EPWM chapter within the Time-Base submodule section:

Best Regards,

Allison

0 Kshitij Rajesh Dachewar 9 months ago in reply to Allison Nguyen

Prodigy 20 points

Understood. This solves my issue. Thanks Allison.

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TMS320F28379D: Synchronize ePWM1 with external signal connected at GPIO18