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DS90UB948-Q1: How do we change the register when the screen change HV mode to DE mode?

Sherry Liang
Genius 10255 points
Part Number: DS90UB948-Q1
Other Parts Discussed in Thread: DS90UB941AS-Q1, DS90UB901Q-Q1

Dear team,

If the screen change timing mode from HV mode to DE mode, do we need to change any registers in the 948?

When the mode changed and we still use old register configuration, the screen can't work(black). At this time, If we set 948's pattern generation(internal video and timing) , the screen doesn't work either. Only when I set register 0x28's bit7=1&bit1=1(the default value is 0), the screen will work normal under pattern generation mode.

So my questions are below,

1. What is the difference between bit1=0 and bit1=1?

2. If bit7=0 which means 0x28's register is loading from the serializer, but I can't find any register configuration related to the bit1 of 948 in the serializer's registers(DS90UB941AS-Q1). Could you please tell me which register of 941 is related to the bit1 of 948?

Thanks & Best Regards,

Sherry

  • 0
    TI__Mastermind 25955 points

    Hi Sherry,

    Datapath control register 2 is loaded from control words sent in the forward channel.  Asserting bit 7 of this register allows overriding of the forward channel controls via register access for all bits of this register except the dual_link bit (bit 4).

    When bit 7 is asserted, the values are no longer controlled by the forward channel.

    With respect to a comparable 28 bit setting on the 941AS, I am looking into this more deeply with the applications and systems teams.  Please expect an update by Friday.

    Sincerely,
    Bryan Kahler

  • 0 in reply to Bryan Kahler
    TI__Mastermind 25955 points

    Hi Sherry,

    Please provide more information with respect to the panel.  The settings may not be proper here.

    One area to investigate may be the DE polarity.  Please ensure the DE polarity is properly set on the 941 to match the requirements of the panel (or 948 if overriden).  This will be register 0x12 on the 941 and register 0x22 on the 948.

    Sincerely,
    Bryan Kahler

  • 0 in reply to Bryan Kahler
    TI__Genius 10255 points

    Hi Kahler,

    Could you please tell me what is the difference between bit 1=1 and bit 1=0? If bit 1=0, the video signal in the forward channel doesn't include HS, VS, DE, right? But in my understanding, HS,VS, DE are also necessary in normal operation.

    Thanks & Best Regards,

    Sherry

  • 0 in reply to Sherry Liang
    TI__Mastermind 25955 points

    Hi Sherry,

    This information should be included in the forward channel regardless of this setting.  The 28 bit may refer to a legacy mode.

    Sincerely,
    Bryan Kahler

  • 0 in reply to Bryan Kahler
    TI__Genius 10255 points

    Hi Bryan,

    I can find the corresponding register in 947's datasheet as below, but in 941's datasheet this bit is reserved.

    Below is 948's 0x28, but I still don't understand what is the difference between bit1=0 and bit1=1.

    Thanks & Best Regards,

    Sherry

  • 0 in reply to Sherry Liang
    TI__Mastermind 25955 points

    Hi Sherry,

    The bit is for operating with legacy device packet structures.  One such example device that uses the 28 bit packet structure is the ds90ub901q-q1.

    Sincerely,
    Bryan Kahler