DS90UB940-Q1: Reverse SPI function configuration of FPD LINK III

Charles (KAT) Zhang

Part Number: DS90UB940-Q1

Hi All,

Customer is using DS90UB949+DS90UB940 combination, and try to use the reverse SPI function, but still get the function to work, SOC has already sent CS/CLK/DATA to.940, but 949 is not outputing any signal.

According to my understanding, we only need to configure the HSCC_MODE of the two device to 111 to set the device in <high speed,reverse channel SPI mode>, but it doesn't work.

Could you please suggest any other register need to be configured? Thanks.

Best Regards

Charles Zhang

over 7 years ago

0 Steven(Shenzhen) Shi over 7 years ago

TI__Mastermind 30515 points

Yes, you need configure the HSCC_MODE to make the reused pin work at SPI mode.

also, you should make sure the SPI rate in the reverse channel SPI mode due to back channel rate limitation. if bc rate is set at 5Mbps, the maximum SPI read clock freq. is <58KHz. please make sure your reverse spi timing to match ux94x's request.

btw, you can post this issue in helpme system.

best regards,

Steven

0 Charles (KAT) Zhang over 7 years ago in reply to Steven(Shenzhen) Shi

TI__Intellectual 1565 points

Hi Steven,

Thanks for reply.

But in customer's board, we did some verification, even the SPI CLK is about 5K, there is still no CLK output.

Do you know if there are other limitation. Thanks.

Best Regards
Charles Zhang

0 Steven(Shenzhen) Shi over 7 years ago in reply to Charles (KAT) Zhang

TI__Mastermind 30515 points

NOT.
we have one app. note on SPI in our sharing point, please follow up our timing design request.

best regards,
Steven

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DS90UB940-Q1: Reverse SPI function configuration of FPD LINK III