BOOSTXL-DRV8305EVM: F28379D with DRV8305 does not work at 200MHz

Dhammika Wijesundera

Part Number: BOOSTXL-DRV8305EVM
Other Parts Discussed in Thread: LAUNCHXL-F28379D, DRV8320

Hi,

I am using BOOSTXL-DRV8305EVM with the LAUNCHXL-F28379D evaluation board to run a PMSM motor. If I set the PLL of F28379D above 190MHz, the motor starts to rattle violently.

I have a custom made board that has F28773S and DRV8320 gate drivers, and that can go to 198MHz which is the maximum you can go with the crystal used in it. There is no issue with running the same code in that one.

Do you have any idea what the reason would be.

Thanks,

Dhammika

over 4 years ago

0 Adam Sidelsky over 4 years ago

TI__Guru 61200 points

Dhammika,

Thanks for posting on the MD forum!

Have you checked the PWM inputs of the DRV at less than 190MHz PLL and above 190MHz PLL? I think you might find some difference there that's leading to your issue.

Regards,

-Adam

0 Dhammika Wijesundera over 4 years ago in reply to Adam Sidelsky

Intellectual 645 points

Hi Adam,

I checked the PWM outputs at different frequencies. I do not see any difference. However, one characteristic I see at 200MHz is that the motor makes a sound when I press the run button of the debugger. That is because PWM signals come out very briefly when the run button of the debugger is pressed.

The PWM outputs come out like that even at 190 MHz and lower frequencies as well. But the motor does not make any sound. That is the only difference I see between frequencies above 190 MHz and below 190 MHz.

Regards,

Dhammika

0 Dhammika Wijesundera over 4 years ago in reply to Dhammika Wijesundera

Intellectual 645 points

Hi Adam,

I removed the BOOSTXL-DRV8305EVM from the LAUNCHXL-F28379D board and ran the debugger again. When I do that, the PWM signals never come out when I press the debugger's run button. I am completely puzzeled by this behavior.

Thanks,

Dhammika

0 Dhammika Wijesundera over 4 years ago in reply to Dhammika Wijesundera

Intellectual 645 points

I have to clarify my post above. When the debugger's run button is pressed, I do not expect any PWM signals.

The PWM signals should come out when the RunMotor variable (as in TI example code) is set to 1. So, the LAUNCHXL-F28379D works as expected. The problem seem to occur when I attach the BOOSTXL to the launch pad.

Thanks,

Dhammika

0 Dhammika Wijesundera over 4 years ago in reply to Dhammika Wijesundera

Intellectual 645 points

Hi Adam,

I think I found the issue. My own logic may have caused this. Still investigating.

Thanks,

Dhammika

0 Adam Sidelsky over 4 years ago in reply to Dhammika Wijesundera

TI__Guru 61200 points

Dhammika,

Glad to hear the issue is progressing. Please let us know what you find.

Regards,

-Adam

0 Dhammika Wijesundera over 4 years ago in reply to Adam Sidelsky

Intellectual 645 points

Hi Adam,

I found the issue. Sorry to bother you unnecessarily. There was nothing wrong with the BOOSTXL or LAUNCHXL borads. The PWM settings were also OK (I used the macros in TI example for PWM period calculations).

I had a calibration for the magnet's position with respect to the index pulse of the encoder. After starting, I do not change the encoder's angle immediately after the index pulse is detected. I change it gradually to make sure motor rotates smoothly. I was correcting that angle to quickly. I also have forgotten to change the delays that depended on the CPU frequency.

Thanks,

Dhammika

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BOOSTXL-DRV8305EVM: F28379D with DRV8305 does not work at 200MHz