DRV8304: Question about PWM Signal in Synchronous and Asynchronous Mode.

Hi Nikolaoas,

Thanks for posting to the MD forum!

What PWM frequency are you using, and are you using the nBRAKE function on INLC or setting the BRAKE bit in Driver Control Register (0x02, bit 1)?

Could you share your schematic if possible?

Hi,

EDITED: PWM is 10 KHZ

I am using the INCL as Brake and not the SPI Register. The schematic is on this post :

and my new PCB has now a better view:

King Regards,

Nikos

Hi Nikos,

How are you using the BRAKE pin on INLC? Do you pull it low at any point while sending a PWM to INHC? 

Could you share your SPI settings? I would like to recreate this test on a BOOSTXL-DRV8304H EVM at some point, although I had to order one and should be in by the end of the week. I can try and recreate this issue on another EVM in the meantime and see what I can do to debug the signal.

Have you tried installing another DRV8304 chip and seen a similar issue? 

Hi,

I make the following,

1. Initialize the Timer and Interrupts.
2. Remove Brake.
3. Set PWM to 20%.
4. Align the Motor.
5. Set PWM to 0 %.
6. Let Timer Interrupt to make the commutation.

I have two different Boards and I have exactly the same behavior.

I am using the following configuration:

Some measurements in Asynchronous mode:

HAL Freq: 100 Hz. As you can see the strange ramp up is very visible.

HAL Freq: 200 Hz. As you can see the ramp up is smaller.

HAL Freq: ca. 670 Hz As you can see the peak is very very small now.

In Synchronous Mode I have for the 3 different HAL Freq. the same curve.

King Regards,

Nikos

Hi Nikos,

Thank you for sharing your configuration and the screenshots of behavior. I will run your test setup with a similar device and try to replicate and debug results and give you an update by the end of the week.