TMS320F280025C: synchronization error between each EPWM module

Yale Li 李耀先

Part Number: TMS320F280025C
Other Parts Discussed in Thread: C2000WARE

Hi Team,

My customer found that the EPWM module which is synchronized always lag 2 TBCLKs from the source EPWM module. And I verified it through the demo provided by C2000ware.

Please take a look of it.

Thanks & Regards

Yale

over 2 years ago

0 Uttam Reddy Pailla over 2 years ago

TI__Expert 6020 points

Hi Yale,

What is the example you have tested from C2000 ware? I can implement from my end.

Best,

Uttam

0 Yale Li 李耀先 over 2 years ago in reply to Uttam Reddy Pailla

TI__Expert 4660 points

Hi Uttam,

I use this example:

C:\ti\c2000\C2000Ware_4_02_00_00\driverlib\f28002x\examples\epwm --> epwm_ex3_synchronization

My CCS version: 12.1.0

myEPWM1 default setting:

myEPWM2 default setting:

1. Use 100MHz clock for TBCLK(10ns per step). Change myEPWM2 Phase Shift Value from 300 to 0:

You can see that the waveform of EPWM2 is lagging for EPWM1 about 2 TBCLKs(20ns).

***************************************************************************************************************

2. Based on case1, change myEPWM2's Phase Shift Value from 0 to 5:

The 2 of 5 TBCLKs play the offset role.

***************************************************************************************************************

3. disable all the synchronization's configurations of both myEPWM1 and myEPWM2:

No lagging.

Thanks & Regards

Yale

+1 Luke Jones over 2 years ago in reply to Yale Li 李耀先

TI__Mastermind 27600 points

Hi Yale,

On F2802x(not F28002x), we actually instruct the user to use a phase shift of 2 to truly synchronize two EPWM modules, since there is a propagation delay before the sync takes effect in the synchronized EPWMs. This is detailed in the following thread:

https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/279536/epwm-2-cycle-delay-on-sync

From looking at the TRM, we don't make the same recommendation for F28002x, but I will confirm this with other EPWM experts. I verified on my side that the same delay occurs with the sync, and using a phase shift value of 2 perfectly lines of the EPWM modules when the clock divider is switched from 8 to 1.

I will try to get back to you by tomorrow once I confirm this with other EPWM experts.

Thank you,

Luke

+1 Luke Jones over 2 years ago in reply to Luke Jones

TI__Mastermind 27600 points

Hi Yale,

I was mistaken, this sync delay exists on all Gen 3 devices, including F28002x. The same note from the e2e I linked to should be used: If TBCLK = SYSCLKOUT, TBPHS should be 2, otherwise TBPHS should be 1 when a EPWM SYNCOUT signal is used to sync another EPWM module.

0 Yale Li 李耀先 over 2 years ago in reply to Luke Jones

TI__Expert 4660 points

Thank you, Luke. It's very helpful.

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F280025C: synchronization error between each EPWM module