DRV8242-Q1: Can't clear nFAULT

Pete Swenson

Part Number: DRV8242-Q1

Tool/software:

I’m having trouble getting the DRV8242S-Q1 to work. After power-on and I set nSLEEP high, nFAULT goes low. Then I send the CLR_FLT command (0x80 to register 0x08), but I never see nFAULT go high. Is there some special sequencing I should follow? Does the state of DRVOFF (or other control lines) matter when sending CLR_FLT?

Also, in 7.5.2 of the datasheet, it says the two MSBs are 1 – is this always the case? So when I read the DEVICE_ID, should I ignore the two MSBs?

1 month ago

0 Shinya Morita 1 month ago

TI__Mastermind 34905 points

HI,

Thank you for your question. Our expert will reply to you in a day or two

0 Keerthivasan Kumanan 1 month ago in reply to Shinya Morita

TI__Genius 12785 points

Hi Pete,

Please see the following FAQ:

(+) [FAQ] DRV8243/44/45-Q1. 20-40us nSleep pulse input requirement for H-Variant - Motor drivers forum - Motor drivers - TI E2E support forums

Best,

Keerthi

0 Pete Swenson 1 month ago in reply to Keerthivasan Kumanan

Prodigy 60 points

That FAQ is for the H variant. I am using the DRV8242S-Q1, the SPI (S) variant.

0 Keerthivasan Kumanan 1 month ago in reply to Pete Swenson

TI__Genius 12785 points

Hi Pete,

Are you able to read back any registers?

If so can you read the fault summary as well as device_Id?

Yeah the first two bits are just 1 in the SDO frame:

Are you sending clr_flt after t_com

Best,

Keerthi

0 Pete Swenson 1 month ago in reply to Keerthivasan Kumanan

Prodigy 60 points

Yes. Can I attach a Saleae logic analyzer trace capture? I tried and it didn't work.

0 Keerthivasan Kumanan 1 month ago in reply to Pete Swenson

TI__Genius 12785 points

Hi Pete,

Yeah it would be helpful if you can attach those captures.

Best,

Keerthi

0 Pete Swenson 1 month ago in reply to Keerthivasan Kumanan

Prodigy 60 points

I try to attach a file and it fails. Any ideas?

0 Pete Swenson 1 month ago in reply to Keerthivasan Kumanan

Prodigy 60 points

Can I just email it to you?

0 Keerthivasan Kumanan 30 days ago in reply to Pete Swenson

TI__Genius 12785 points

Hi Pete,

Yeah sure that works. I will send my email over private message.

Best,

Keerthi

0 Pete Swenson 19 days ago in reply to Keerthivasan Kumanan

Prodigy 60 points

Have you found anything on this? I really need a solution.

0 Keerthivasan Kumanan 19 days ago in reply to Pete Swenson

TI__Genius 12785 points

Hi Pete,

Can you just capture one SPI frame on an oscilloscope or take a screenshot of the saelae capture on your side. Can you double check if you SPI frame setup is correct:

CPOL = 0 and CPHA = 1

When you send the CLR_FLT command, do you get the following response?

SDI: 0x0880

SDO: 0xC009

Best,

Keerthi

0 Pete Swenson 18 days ago in reply to Keerthivasan Kumanan

Prodigy 60 points

CPHA was 0. I changed it to 1 and nFAULT clears now. That wasn't very obvious in the datasheet.
Thanks!