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DS90UB941AS-Q1: I2C communication failure with DS90UH948-Q1 via

Vincent Wang
Prodigy 25 points
Part Number: DS90UB941AS-Q1


Hello,

      Sedes 941 register 0x6 can read remote 948 ID value 0x70，and  i think the FPD-LINK /I2C physical line connect well. 

      However, the 948 register viawe cannot be read & write via I2C, failure eror reported,  and what's this isue and how to read/ wirte remote register?

  • 0
    TI__Guru** 103215 points

    Hello Vincent,

    Can you share more information about your setup here? Does the 941AS have a DSI source connected and active or no? Is the DSI receiver enabled in register 0x01 of 941AS? What hardware is being used here? EVMs? Custom PCBs? What sort of cable is being used? Can you share any pictures?

    It sounds like the back channel link is working which is why you are seeing an address in the 941AS for the DES_ID, but the forward channel link may not be entirely stable which is why you are unable to write/read remote registers 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Prodigy 25 points

    Hello Casey,

          Thanks for you reply.  We use TDA4 EVM + customer display board with DS90UB948-Q1,  a STP line is used to connect port 0 of 941AS and port 1 of 948 and configed normal mode.

         Now there is no DSI source conected and use pattern generator mode to test firstly   the  0x1 resgister of 941AS is set to disable DSI. Besides, the register 0x64 of 941AS is set to enable pattern generator mode, also set 0x3 I2C pass through , 0x17 i2c PASS ALL. 

        So if there are more registers need to be set in this way using, also like you said, this maybe caused by the forward channel link issue , then how to check it ? Look fprward your professioanl advice to deal wth this issue~~

         

  • +1 in reply to Vincent Wang
    TI__Guru** 103215 points

    Vincent,

    The 948 is designed to use port 0 if it is operated in single link mode. If you need to use port 1, then you will need to locally reconfigure the 948 to use port 1 for single link mode (can't be done through the FPD-Link remotely). 

    Set 0x34 = 0x1A to force single link port 1 mode (program to the 948 locally)

    Best Regards,

    Casey