DRV8353R: Reading Don't Care Bits for additional diagnostic

Angelika Hennerkes

Part Number: DRV8353R

Hi BLDC Team,

I would have a question regarding the SPI communication of DRV8353RS. Are the Don't Care Bits ( B15-B11) of the SDO output Data word always 0 when reading and could this be used as an additional diagnostic e.g. to ensure that you are actually receiving feedback when reading the status registers?

Thanks and best regards,

Angelika

over 3 years ago

0 Isaac Lara over 3 years ago

TI__Mastermind 23045 points

Hello Angelika,

Thank you for your question and for posting to the MD forum. In the past I have not tested that many data packets to say that B15-B11 dont care bits are always 0. I think I need to verify check with digital design team to see if it would be possible to get a value other than 0 for these bits. I will get back to you on this as soon as possible.

Best,

Isaac

0 Isaac Lara over 3 years ago in reply to Isaac Lara

TI__Mastermind 23045 points

Hey Angelika,

Still waiting to hear back from digital design on this item. I should have a response by Friday I will keep you posted as soon as I hear back from them. Thank you for the patience!

Best,

Isaac

0 Isaac Lara over 3 years ago in reply to Isaac Lara

TI__Mastermind 23045 points

Hey Angelika,

Spoke to design team today, they are still looking into this issue, they need to verify the digital core to see if this is padded with 0's or if this is dependent on data coming in from another module. Will get back to you as soon as they provide me the details.

Best,

Isaac

0 Angelika Hennerkes over 3 years ago in reply to Isaac Lara

TI__Prodigy 600 points

Hi Issac, thanks for your support. Did you receive feedback from our colleagues yet? Best, Angelika

0 Isaac Lara over 3 years ago in reply to Angelika Hennerkes

TI__Mastermind 23045 points

Hey Angelika,

Nothing back yet from the team, but we have a meeting with design today so I will bring up this issue at the meeting, and let you know any updates or outcomes.

Best,

Isaac

0 Aaron Barrera over 3 years ago in reply to Isaac Lara

TI__Mastermind 26046 points

Hi Angelika,

We confirmed with design that the 5 "Don't Care" bits are always "0" if SDO is functioning correctly. If there is an internal device failure that causes the SDO to not actively drive the data bits at that register, then the open drain pullup should keep those five "Don't Care" bits as "1", so you can use this as a diagnostic for your application.

Thanks,
Aaron

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DRV8353R: Reading Don't Care Bits for additional diagnostic