SyncIn with external source

The

From the ePWM manual.

Time-base synchronization input (EPWMxSYNCI) and output (EPWMxSYNCO) signals.
The synchronization signals daisy chain the ePWM modules together. Each module can be configured
to either use or ignore its synchronization input. The clock synchronization input and output signal are
brought out to pins only for ePWM1 (ePWM module #1). The synchronization output for ePWM1
(EPWM1SYNCO) is also connected to the SYNCI of the first enhanced capture module (eCAP1).

So you can synchronize only the ePWM1 module with the EPWMxSYNCI signal. Then you will have to configure the ePWM1 module to take this as a sync signal and if you want to sync all wPWM modules to this same signal then use this as a ePWM1 module syncout signal and not the CTR=0 . You will also have to define in GPIO settings that the pin is for EPWMSYNCI. I hope this helps.

Example:

PWM:

EPwm1Regs.TBCTL.bit.PHSEN = TB_ENABLE; // Load the time-base counter with the phase register when an EPWMxSYNCI input signal occurs or
when a software synchronization is forced by the SWFSYNC bit

EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN;   // source of the EPWMxSYNCO signal: EPWMxSYNC

GPIO:

GpioCtrlRegs.GPBMUX1.bit.GPIO32 = 2;        // 0=GPIO32      1=SDAA      2=EPWMSYNCI  3=/ADCSOCAO

JHi

Thank you. I will try it.

Hello JHi,

I would like to synchronize the pwm1 with an external trigger source @10us, so I set:

--------------------------------------------------------------

EPwm1Regs.TBCTL.bit.PHSEN = TB_ENABLE;

GpioCtrlRegs.GPBMUX1.bit.GPIO32 = 2;

--------------------------------------------------------------

but i see that the Pwm Interrupt  is called  twice.

Internal counter and external source both call the PwmInterrupt because counter is set to ZERO.

( EPwm1Regs.ETSEL.bit.INTSEL =  ET_CTR_PRDZERO;)

Of course this generates several problems.

How can I avoid the pwm ramp to start again without the external trigger?

Thanks

M.

It is supposed to start the ramp again, otherwise it is not synchronized. But what you should do is to change interrupt to trigger from period not zero.

EPwm1Regs.ETSEL.bit.INTSEL = ET_CTR_PRD.

In my case I need to generate pwm interrupt at zero for other reasons.

I wonder if there is the possibility to change the pwm period

in order to lock the external trigger  without "breaking" the counter ramps.

Thanks

M.

One possibility would be to add 2 to phase shift. Then the clock would not go to zero but to 2 and it will also compensate delay from the sync signal.

EPwm1Regs.TBPHS.half.TBPHS = 2;     // Compensation to delay (2*SYSCLKOUT) of the sync signal

It works if the external trigger is late, but if it comes earlier there is no counter=0 and no interrupt generation.

I will use GPIO32 as generic GPIO to perform a smooth adjustment of pwm_period.

M.

Would it be then possible to disable the interrupt from ePWM unit and do the same stuff in external interrupt function? You could still leave the synchronization.

Yes, the solution is to disable all interrupts called by counter=zero.

Now I have Epwm interrupt called by external trigger.

M.