TMS320F280025C: GPIO -> Input-Xbar -> EWPM AQ, delay time is too long

Julia Li

Part Number: TMS320F280025C

Tool/software:

Hi Champs,

Customer uses Input-Xbar to route the signal on GPIO0 to the ePwm4 module as its synchronization signal, and then uses this signal as the trigger source for the T1 event, and the AQ module sets the PWM high when the T1 event occurs.

However, during the test, it was found that the PWM AQ was delayed by 170ns, what is the reason for this? Is this delay time normal?

In the figure below, channel 1 is the synchronization signal routed to ePWM4, and channel 4 is the output ePWm4A PWM waveform.

Thanks!

Julia

1 month ago

0 Luke Jones 1 month ago

TI__Genius 18000 points

Hi Julia,

I believe I have seen this issue before, I will discuss with other EPWM experts about the likely root cause and get back to you.

Thank you,

Luke

0 Julia Li 1 month ago in reply to Luke Jones

TI__Expert 3290 points

Hi Luke,

Do we have update now?

Thanks!

Julia

0 Luke Jones 1 month ago in reply to Julia Li

TI__Genius 18000 points

Hi Julia,

A delay of 170ns would correspond to 17 SYSCLKs which is unusual. There is a propagation delay of a few CLK cycles whenever routing a signal through the Input XBARs as an external sync source.

If you set an action qualifier on TBCTR=0 with a TBPHS value of 0, do you see the same delay? Perhaps the delay is coming from the T1 logic.

Thank you,

Luke

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TMS320F280025C: GPIO -> Input-Xbar -> EWPM AQ, delay time is too long