DRV8308: SDATAO state during inputting to SDATAI

Yusuke Mukuno

Expert 7395 points

Part Number: DRV8308

Hi Expert,

Could you please let me know the SDATAO state during inputting to SDATAI? (Low or High-Z?)

Customer found the low signal output on their board.(Is it correct operation?)

Also, they want to change to High-Z state during this time.

Could you please give me your advise?

Thanks

Muk

over 4 years ago

0 Paul Parrot over 4 years ago

TI__Intellectual 2345 points

Hey Muk,

I'll need to test this on my end. I should be able to run a few tests tomorrow morning and get back to you then!

Regards,

Paul

0 Yusuke Mukuno over 4 years ago in reply to Paul Parrot

TI__Expert 7395 points

Hi Paul-san

Thank you for your supporting.

Do you have any update?

Thanks

Muk

0 Paul Parrot over 4 years ago in reply to Yusuke Mukuno

TI__Intellectual 2345 points

Hey Muk-san,

Apologies for the delay.

I tested this with the DRV8308EVM and SDATAO was high during an input transaction on SDATAI. I believe the EVM has an external pullup resistor on SDATAO so if your customers board does not have an external pullup I would expect SDATAO to be High-Z.

Could you ask them to provide some waveforms of the 4 SPI lines showing the SDATAO low during this operation?

Regards,

Paul

0 Yusuke Mukuno over 4 years ago in reply to Paul Parrot

TI__Expert 7395 points

Hi paul-san,

I attached the customer waveform.

SDATAO was pulled low at Read access(the read bit is latched timing).

Thanks

Muk

0 Paul Parrot over 4 years ago in reply to Yusuke Mukuno

TI__Intellectual 2345 points

Hey Muk-san,

Thank you for providing the waveforms!

It looks like the SDATAO line goes low immediately after receiving the READ bit. I will take a closer look at this interaction with my setup.

Can you confirm if they have an external pullup resistor on SDATAO? Also, are they able to successfully communicate with the device using SPI?

Regards,

Paul

0 Yusuke Mukuno over 4 years ago in reply to Paul Parrot

TI__Expert 7395 points

Hi Paul-san,

>Can you confirm if they have an external pullup resistor on SDATAO?

Yes, they have the external pullup resistor.

>Also, are they able to successfully communicate with the device using SPI?

Yes, They are able to successfully communicate with SPI.

This question is for the difference between datasheet figure and waveform.

Thanks

Muk

0 Paul Parrot over 4 years ago in reply to Yusuke Mukuno

TI__Intellectual 2345 points

Hey Muk-san,

My apologies, my previous statement was incorrect. I repeated my original test and looking a bit closer it SDATAO goes get pulled low as soon as the READ bit is read from SDATAI. So your customers device is operating normally. I don't believe there is a way to change it to high-z during this time.

Is there a particular reason the customer wants SDATAO to be high-z during this time?

Regards,

Paul

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DRV8308: SDATAO state during inputting to SDATAI