TMS320F28377S: Execution delay from input to EPWM module

Sudheer Sai4

Part Number: TMS320F28377S

Hi,

We are using TMS320F28377S DSP IC in one of the project where we are driving a 28VDC BLDC motor. We are using EPWM module to generate PWMs from DSP. Pin 1 to Pin 7. Configured Hall sensor input as GPIOs to pins 161, 162 and 163. As we are running the motor, we observed there is a current surge. We ocompared Hall sensor inputs and EPWM outputs and understood there is a delay of 300uS in execution. We analyzed the code execution delay and found it contributes only 70uS delay. However DSP hardware itself causing 230uSec delay. Could you please help us on this issue. Attached monitored waves.

Waveform names are self explanatory. the delay can be observed between Hall A (Input at DSP pin) rising edge to Btm A (output of DSP) falling edge.

over 6 years ago

0 Nima Eskandari over 6 years ago

TI__Guru 52020 points

I'm not following the question, what is the delay measure between? Which events?

0 Sudheer Sai4 over 6 years ago in reply to Nima Eskandari

Prodigy 150 points

Hi Nima,

The delay is from the event the DSP detecting the input HALL signal to the event that gives output on the DSP output pin for the H-bridge control.

Please let me know if you need more information.

0 Nima Eskandari over 5 years ago in reply to Sudheer Sai4

TI__Guru 52020 points

This is most likely due to how you have set up your PWM. If they are using shadow mode and you write to change the duty/period, they take effect on the next loading event instead of immediately.

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TMS320F28377S: Execution delay from input to EPWM module