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DS90UB948-Q1: When DS90UB949-Q1 is used in combination with DS90UB948-Q1, the display screen has no content display

Kailyn Chen
Genius 9560 points
Part Number: DS90UB948-Q1
Other Parts Discussed in Thread: DS90UB949-Q1, , ALP

Hello,

One customer has below problem used DS90UB948+DS90UB949. 

Ds90ub949-q1 is used with DS90UB948-Q1,hdmi output to ds90ub949, 948 output to screen， the screen is not displayed but the backlight of the screen is bright, and i2c can communicate with Ds90ub949-q1 and S90UB948-Q1.
T he pattern test is performed, the screen is also not displayed.

Perform the configuration according to 4.4 Cases in the SNLA132G document. Use the Without FPD-link III scheme and configure 948 to enter Pattern test. The screen displays no information.
code show as below：
{
//1. Set Pixel Clock and Active Frame Size 1920
ds90ub948_single_write(ds90ub948, 0x66, 0x07);
ds90ub948_single_write(ds90ub948, 0x67, 0x80);

ds90ub948_single_write(ds90ub948, 0x66, 0x08);
ds90ub948_single_write(ds90ub948, 0x67, 0x87);

ds90ub948_single_write(ds90ub948, 0x66, 0x09);
ds90ub948_single_write(ds90ub948, 0x67, 0x43);
//2. Set Total Frame Size 2200
ds90ub948_single_write(ds90ub948, 0x66, 0x04);
ds90ub948_single_write(ds90ub948, 0x67, 0x98);

ds90ub948_single_write(ds90ub948, 0x66, 0x05);
ds90ub948_single_write(ds90ub948, 0x67, 0x58);

ds90ub948_single_write(ds90ub948, 0x66, 0x06);
ds90ub948_single_write(ds90ub948, 0x67, 0x46);

//3. Set Back Porch
ds90ub948_single_write(ds90ub948, 0x66, 0x0C);
ds90ub948_single_write(ds90ub948, 0x67, 0x94);

ds90ub948_single_write(ds90ub948, 0x66, 0x0D);
ds90ub948_single_write(ds90ub948, 0x67, 0x24);
//4. Set Sync Width
ds90ub949_single_write(ds90ub948, 0x66, 0x0A);
ds90ub949_single_write(ds90ub948, 0x67, 0x2C);

ds90ub948_single_write(ds90ub948, 0x66, 0x0B);
ds90ub948_single_write(ds90ub948, 0x67, 0x05);
//5.Set Sync Polarities
ds90ub948_single_write(ds90ub948, 0x66, 0x0E);
ds90ub948_single_write(ds90ub948, 0x67, 0x00);

//6.Enable Pattern Generation
ds90ub948_single_write(ds90ub948, 0x65, 0x0C);
ds90ub948_single_write(ds90ub948, 0x64, 0x05);
}
How should I judge the problem?
How to make patgen work only on deserializers before using patgen via FPD-Link?

The Display parameter is as following:


Please give me a reply. Thank you very much

Best regards

Kailyn

  • +1
    TI__Mastermind 25765 points

    Hi Kailyn,

    What you have programmed is 1920x1080p for the 948 patgen.

    Total timings which you have programmed:

    Htotal: 2200

    Vtotal: 1125

    HActive: 1920

    VActive: 1080

    HBP: 148

    VBP: 24

    HSW: 44

    VSW: 5

    Positive polarity.

    You have also enabled external clock mode.

    This timing does not match the timing table you have posted. Can you confirm the timing I have listed is correct and compatible with the display?

    Kailyn Chen said:
    How to make patgen work only on deserializers before using patgen via FPD-Link?

    This is what you currently have programmed. There is no patgen coming from the SER for this code. You can however program the SER to enable patgen if desired.

    *Note: since you have external clock mode enabled, the 948 is expecting a PCLK coming from the SER input. So if there is no HDMI input to the 949 at the moment, you will want to change this to internal clock mode.

    Also, if possible, using our ALP software to program patgen would be much easier, as it has an interface to choose all patgen configs.

    Regards,

    Ben