DRV8308EVM: Problem writing registers using SPI

Steve Peake

Prodigy 10 points

Part Number: DRV8308EVM
Other Parts Discussed in Thread: DRV8308,

Tool/software:

I've started evaluating the DRV8308 motor driver, using the DRV8308EVM board.

I abandoned the Windows eval software, as it was unable to do anything other than open loop PWM control.

I've started developing my own interface from a microcontroller, trying to read & write to the DRV8308 using SPI.

I can read the FAULT register, and get the result 0x18, as suggested in the datasheet. This strongly suggests that I have working SPI comms with the DRV8308.

When I try to write to the FAULT register, I only ever get 0xFF returned. The datasheet says I can write 0x00 to clear the fault register.

Test process:

Boot
Read FAULT register: receive 0x18
Write 0x00 to FAULT register: receive 0xFF
Read FAULT register: receive 0x18

The datasheet mentions ENABLE needing to be high to burn data to the OTP storage on the CRV8308, but I don't want to do this while still experimenting with the device.

Any suggestions what I am missing?

Thanks

Steve

5 months ago

+1 Yara Al Shami 5 months ago

TI__Genius 15355 points

Hi Steve,

Just want to clarify that ENABLE is high when you are reading and writing to the fault register (0x2A)? OTP will only be programmed if ENABLE is high AND this sequence happens

this E2E post talks a little bit about the relationship with ENABLE and SPI:

https://e2e.ti.com/support/motor-drivers-group/motor-drivers/f/motor-drivers-forum/1105618/drv8308-relationship-between-spi-and-enable-signals

Regards,

Yara

0 Steve Peake 5 months ago in reply to Yara Al Shami

Prodigy 10 points

Thanks for the response. I had read that post when searching for a solution, but it still only linked the ENABLE line being high to the OTP programming sequence, not with general read/write operations. I can read the FAULT register with ENABLE low. Now you've confirmed I won't be accidentally triggering the OTP process, I'll try writing with the ENABLE line high.

Thanks for the help.

Regards
Steve

0 Steve Peake 5 months ago in reply to Steve Peake

Prodigy 10 points

I've driven ENABLE high while reading/writing, and am now getting the results I'd expect.

Initial FAULT read: 0x18

Write 0x00 to FAULT

Second FAULT read: 0x00

Thanks for the assistance

Regards

Steve

+1 Yara Al Shami 5 months ago in reply to Steve Peake

TI__Genius 15355 points

Glad I could help!

Regards,

Yara

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DRV8308EVM: Problem writing registers using SPI