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SN75DP130: Meaning of values in 22h -27h

icecrackers
Prodigy 80 points
Part Number: SN75DP130

Hi TI,

May we know how to interpret the values from Offset = 22h~27h?

We are testing our redriver and noticed that the values here changes when there is an I2C change.

It would help our test if we could know the meaning of the values.

Thank you very much.

Best regards,

ice

  • 0
    TI__Guru**** 176641 points

    Ice

    Registers 0x22h to 0x27h are for TI internal digital debug test only. You don't need info from 0x22h to 0x27h registers to debug the issue.

    What issue do you have with your test? 

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 80 points

    Hi David,

    Thank you. I figured 0x22h to 0x27h reflects the DPCD registers setting because when I try to change the values when linked training is off it also updates.

    There is no issue right now, but I'd like to know what it could mean cause I'm trying to replicate the auto DPCD settings on a redriver for another unit.

    The need for the information is for experimental purposes only.

    I was hoping I could maybe get an idea of what it means for our experiments.

    I understand if we can't have a guide though.

    Thank you very much.

    Best regards,

    Ice

  • 0 in reply to icecrackers
    TI__Guru**** 176641 points

    Ice

    The DPCD registers monitored by the DP130 are listed in Figure 17 when link training is enabled. You can use local I2C registers offset 0x1Ch, 0x1Dh, 0x1Eh, and 0x1Fh to read the DPCD registers. Three registers (from 1Ch to 1Eh) are used as the address to the DPCD register and another one (1Fh) as data to be read/written.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 80 points

    Hi David,

    Right now, our only available utility is RW Everything because the local I2C is connected to the SMBus.

    Unfortunately, using that utility we can't read from 0x1Ch, 0x1Dh, 0x1Eh, 0x1Fh but we can read the values in 0x22h~0x27h.

    I want to read the values that are brought by auto link training.

    Do you have another suggestion?

    Thanks.

    Ice

  • 0 in reply to icecrackers
    TI__Guru**** 176641 points

    Ice

    If you have a AUX monitor such as Unigraf DPA-400, then you can use it to capture the AUX traffic between the source and the sink to read the DPCD register content. Otherwise you have to find a way to read the DP130 DPCD registers, not the value in registers 0x22h-0x27h. Values in registers 0x22h-0x27h are TI internal digital debug test only.

    Thanks

    David 

  • 0 in reply to David (ASIC) Liu
    Prodigy 80 points

    I see. Thanks for the information David!