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Original question:

SN75DP130: The SN75DP130DSRGZT output don't responce to the setting.

SN75DP130: Can't config reg 1FH through I2C

CHEN YAN
Intellectual 1430 points

Part Number: SN75DP130

Take 00103h for instance, 1C,1D,1E is config as 00,01,03, then to modify the values of 1F bit 1:0 and 4:3, but the value of 1F is keep 00 whatever input.

Now config I2C offset address as following:
1CH=00H 1DH=01H 1EH=03H 04H=00H, and 1FH keeps 00.

The schematic and config datasheet are attached.slla349.pdf

2248.DP Re-driver.pdf

  • 0
    TI__Guru**** 189451 points

    Chen

    Would you please write to and read from address 0x20h bit 0, bit 0 is BIT_INVERT, which means the value read is in the inverse of that written? I want to make sure i2c is working properly.

    You should write to 0x04h first to disable link training and then try to overwrite the DPCD register.

    Also as I was pointed out in my other e2e post, given that DP130 is connected to both source and sink DP connector and if the cable will be changed between source and sink, DP130 is not best suited for this particular application. 


    Thanks
    David

  • 0 in reply to David (ASIC) Liu
    TI__Intellectual 1430 points
    When write 0 to 0x20h bit 0，the value read is 1，
    write 0 to 0x20h bit 1，the value read is 0
  • 0 in reply to CHEN YAN
    TI__Guru**** 189451 points
    Yan

    It looks like the I2C is working, are you following the same sequence that is the slla349.pdf app note? Also, when you change the TX VOD level, are you seeing the waveform change on the scope?

    Thanks
    David