ePWM3 and ePWM4 sync

Mario,

I think your main issue is in:
PWM_disableCounterLoad(myPwm4); // Disable phase loading

If you change disable to enable I think you'll be closer (ie PWM4 should have phase loading enabled).

Hopefully this helps.


Thank you,
Brett

Hi Brett,

thank you for replying.. I tried your sugestion (without success) before I create a new post, in fact I've seen examples with the slave PWM counter enabled and I even tried to change the lines

PWM_setSyncMode(myPwm3,PWM_SyncMode_CounterEqualZero);     // Sets PWM3x as the Master
PWM_setSyncMode(myPwm4,PWM_SyncMode_EPWMxSYNC);              // Sets PWM4x as the Slave

When I was running out of ideas I tried combinations of these lines to change ePWMs master and slave between ePWM3 and ePWM4 but the result wasn't good so far..

I am not sure if this is the problem but, how does the micro knows that ePWM4 should follow ePWM3? 

He knows that just by enabling the slave PWM counter and setting the SyncMode??

Am I missing some comand to associate the Sync out put of ePWM3 to the Sync input of ePWM4??

Best regards,

Mário

Hi Brett,

I followed your advice, but I couldn't see the PWMs synchronized on the scope..

How does the PWM_setSynchMode() should be initialized for this case?

I'm starting to think that the code might be ok, I just can't see it on the scope.

I there any other initialization needed for this purpose? I've seen examples with initializations on the GPIO to set pins SYNC_in and SYNC_out, I don't think that's the problem but...

Thanks in advance.

Regards,

Mário

Hi Brett, 

we haven't talk for a while, I moved forward with the project but the synchronization problem remains..

I am facing some problems stabilizing the controller due to the unstable current value that I'm acquiring, and I think the problem is that the ADC SOC is not being triggered where I want it to be.

I am still trying to synchronize ePWM3 and ePWM4, where ePWM3 Freq.=20kHz and ePWM4 Freq.=5kHz.

I can't see the two square waves synchronized even with a fixed duty-cycle.

The code that I'm using is as below:

// Initalize PWMs
GPIO_setPullUp(myGpio, GPIO_Number_4, GPIO_PullUp_Disable);
GPIO_setPullUp(myGpio, GPIO_Number_5, GPIO_PullUp_Disable);
GPIO_setMode(myGpio, GPIO_Number_4, GPIO_4_Mode_EPWM3A);
GPIO_setMode(myGpio, GPIO_Number_5, GPIO_5_Mode_EPWM3B);
GPIO_setPullUp(myGpio, GPIO_Number_6, GPIO_PullUp_Disable);
GPIO_setPullUp(myGpio, GPIO_Number_7, GPIO_PullUp_Disable);
GPIO_setMode(myGpio, GPIO_Number_6, GPIO_6_Mode_EPWM4A);
GPIO_setMode(myGpio, GPIO_Number_7, GPIO_7_Mode_EPWM4B);

/************************************************************************
***** PWM Configuration *****
************************************************************************/
void InitEPwm(){

CLK_disableTbClockSync(myClk);

// Enable PWM clocks
CLK_enablePwmClock(myClk, PWM_Number_3);
CLK_enablePwmClock(myClk, PWM_Number_4);

// Setup TBCLK
PWM_setPeriod(myPwm3, EPWM3_TIMER_TBPRD); // Set timer period PWM3
PWM_setPeriod(myPwm4, EPWM4_TIMER_TBPRD); // Set timer period PWM4

PWM_setPhase(myPwm3, 0x0000); // Phase is 0 PWM3
PWM_setPhase(myPwm4, 0x0000); // Phase is 0 PWM4

PWM_setCount(myPwm3, 0x0000); // Clear counter PWM3
PWM_setCount(myPwm4, 0x0000); // Clear counter PWM4

PWM_setCounterMode(myPwm3, PWM_CounterMode_Up); // Count up/down
PWM_setCounterMode(myPwm4, PWM_CounterMode_Up); // Count up/down

PWM_disableCounterLoad(myPwm3); // Disable phase loading
PWM_enableCounterLoad(myPwm4); // Enable phase loading

PWM_setHighSpeedClkDiv(myPwm3, PWM_HspClkDiv_by_1); // Clock ratio to SYSCLKOUT
PWM_setHighSpeedClkDiv(myPwm4, PWM_HspClkDiv_by_1); // Clock ratio to SYSCLKOUT
PWM_setClkDiv(myPwm3, PWM_ClkDiv_by_1);
PWM_setClkDiv(myPwm4, PWM_ClkDiv_by_1);

PWM_setSyncMode(myPwm3,PWM_SyncMode_Disable);
PWM_setSyncMode(myPwm4,PWM_SyncMode_EPWMxSYNC);

// Setup shadow register load on ZERO
PWM_setShadowMode_CmpA(myPwm3, PWM_ShadowMode_Shadow); // Load registers every zero
PWM_setShadowMode_CmpB(myPwm3, PWM_ShadowMode_Shadow);
PWM_setLoadMode_CmpA(myPwm3, PWM_LoadMode_Zero);
PWM_setLoadMode_CmpB(myPwm3, PWM_LoadMode_Zero);
PWM_setShadowMode_CmpA(myPwm4, PWM_ShadowMode_Shadow); // Load registers every zero
PWM_setShadowMode_CmpB(myPwm4, PWM_ShadowMode_Shadow);
PWM_setLoadMode_CmpA(myPwm4, PWM_LoadMode_Zero);
PWM_setLoadMode_CmpB(myPwm4, PWM_LoadMode_Zero);
// Set Actions
PWM_setActionQual_Zero_PwmA(myPwm3, PWM_ActionQual_Set); // Set PWM3A on period
PWM_setActionQual_CntUp_CmpA_PwmA(myPwm3, PWM_ActionQual_Clear); // Clear PWM3A on event A, up count
PWM_setActionQual_Zero_PwmB(myPwm3, PWM_ActionQual_Clear); // Clear PWM3B on period
PWM_setActionQual_CntUp_CmpA_PwmB(myPwm3, PWM_ActionQual_Set); // Set PWM3B on event B, up count
PWM_setActionQual_Zero_PwmA(myPwm4, PWM_ActionQual_Clear); // Clear PWM4A on period
PWM_setActionQual_CntUp_CmpA_PwmA(myPwm4, PWM_ActionQual_Set); // Set PWM4A on event A, up count

PWM_enableSocAPulse(myPwm4); // Enable SOC on A group
PWM_setSocAPulseSrc(myPwm4, PWM_SocPulseSrc_CounterEqualCmpAIncr); // Select SOC from from CPMA on upcount
PWM_setSocAPeriod(myPwm4, PWM_SocPeriod_FirstEvent); // Generate pulse on 1st event

// TRIP ZONE event settings
PWM_enableTripZoneSrc(myPwm3,PWM_TripZoneSrc_OneShot_TZ1_NOT);
PWM_setTripZoneState_TZA(myPwm3, PWM_TripZoneState_EPWM_Low);
PWM_setTripZoneState_TZB(myPwm3, PWM_TripZoneState_EPWM_Low);
PWM_enableTripZoneInt(myPwm3, PWM_TripZoneFlag_OST);

// Set Compare values
PWM_setCmpA(myPwm3, 1000); // Set compare A value PWM3
PWM_setCmpA(myPwm4, 5500); // Set compare A value PWM4

CLK_enableTbClockSync(myClk); // Re-Allow the timer clock to sync to system clock, start counting!

}

I hope you can help me with this issue..

I look forward to hearing from you soon.

Regards,

Mário

Mário Silva said:

PWM_disableCounterLoad(myPwm3); // Disable phase loading
PWM_enableCounterLoad(myPwm4); // Enable phase loading

PWM_setHighSpeedClkDiv(myPwm3, PWM_HspClkDiv_by_1); // Clock ratio to SYSCLKOUT
PWM_setHighSpeedClkDiv(myPwm4, PWM_HspClkDiv_by_1); // Clock ratio to SYSCLKOUT
PWM_setClkDiv(myPwm3, PWM_ClkDiv_by_1);
PWM_setClkDiv(myPwm4, PWM_ClkDiv_by_1);

PWM_setSyncMode(myPwm3,PWM_SyncMode_Disable);
PWM_setSyncMode(myPwm4,PWM_SyncMode_EPWMxSYNC);

PWM_setHighSpeedClkDiv(myPwm3, PWM_HspClkDiv_by_1); // Clock ratio to SYSCLKOUT
PWM_setHighSpeedClkDiv(myPwm4, PWM_HspClkDiv_by_1); // Clock ratio to SYSCLKOUT
PWM_setClkDiv(myPwm3, PWM_ClkDiv_by_1);
PWM_setClkDiv(myPwm4, PWM_ClkDiv_by_1);

PWM_setSyncMode(myPwm3,PWM_SyncMode_CounterEqualZero);
PWM_setSyncMode(myPwm4,PWM_SyncMode_EPWMxSYNC);

Thank you,
Brett

Brett,

Thank you for the reply..

I've tried that before and it doesn't work, with that configuration the ePWM4 stays low..

I'm starting to run out of ideas to solve this..

Is there any other configuration that I should up to?

Thanks a lot.

Mário

Mario,

I'd recommend removing the deadband configuration code for the time being and work on getting synchronization working first.  Once that's settled retry adding in the dead-band.

(I feel like the deadband is currently making it more difficult to evaluate whether synchronization is occurring or not)

I hope this helps!


Thank you,
Brett

Hi Mario,

I have not tried to sync 4 PWM signals but had success synchronising PWM2 with PWM1, if you see the image below extracted from page 24 of the ePWM guide, it should shed some light on your issue.

I also posted some code which worked, but this could probably be used and modified for your purpose and have PWM2 sync'ed to PWM1 and PWM4 sync'ed to PWM3.

http://e2e.ti.com/support/microcontrollers/c2000/f/171/p/323487/1127109.aspx#1127109

Hope this helps,

Ant