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DS90UB949-Q1EVM: PC connect problem

Peter Xu
Expert 6155 points
Part Number: DS90UB949-Q1EVM
Other Parts Discussed in Thread: ALP

Hi team,

My customer uses a 949EVM and the system shows below. Their 948 board is designed by themselves. They can see the content when using 949 pattern. However, they cannot see anything when using the PC as a HDMI source. They can see the HDMI active in ALP. It shows 720p detected. I believe it is because our default EDID only supports 720p.

System:

Timing:

ALP status:

You can see that they have a LVDS to DSI device in the system and the display does not have a EDID, so I generate a 1080P EDID and write a script to write the EDID register. It works and the ALP can detect a 1080p source. However, the screen still shows nothing.

I wonder if our EDID is wrong. Or we miss any setting in 949.

Regards,

Peter

  • 0
    TI__Expert 6155 points

    Hi team,

    Please see the attachment below, it is the EDID script.

    Fullscreen HH983_EDID_SRAM_Write.txt Download 
    # 256 byte EDID to be loaded into HH983 SRAM 
# Edit EDID as needed based on panel specifications

HH983_EDID = [ \
0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x05, 0xD7, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
0xFF, 0x21, 0x01, 0x03, 0x80, 0x32, 0x1F, 0x78, 0x07, 0xEE, 0x95, 0xA3, 0x54, 0x4C, 0x99, 0x26, 
0x0F, 0x50, 0x54, 0x00, 0x00, 0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 
0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x02, 0x3A, 0x80, 0x18, 0x71, 0x38, 0x2D, 0x40, 0x58, 0x2C, 
0x45, 0x00, 0x63, 0xC8, 0x10, 0x00, 0x00, 0x1E, 0x00, 0x00, 0x00, 0xFD, 0x00, 0x17, 0xF0, 0x0F, 
0xFF, 0x0F, 0x00, 0x0A, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x00, 0x00, 0x00, 0xFC, 0x00, 0x31, 
0x39, 0x32, 0x30, 0x78, 0x31, 0x30, 0x38, 0x30, 0x0A, 0x20, 0x20, 0x20, 0x00, 0x00, 0x00, 0x00, 
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x03,
0x02, 0x03, 0x18, 0x40, 0x23, 0x09, 0x06, 0x07, 0x67, 0x03, 0x0C, 0x00, 0x00, 0x00, 0x00, 0x1E, 
0x67, 0xD8, 0x5D, 0xC4, 0x01, 0x1E, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xD7]

board.WriteI2C(serAddr,0x48,0x0D) # Select EDID Page with auto increment
board.WriteI2C(serAddr,0x49,0x00) 

for x in range(0,256):
    board.WriteI2C(serAddr,0x4B,HH983_EDID[x])

    Regards,

    Peter

  • 0 in reply to Peter Xu
    TI__Mastermind 34515 points

    Hi Peter,

    For the above script, please add a variable declaration for serAddr to avoid any issues. I parsed through the EDID and didn't see any immediate problems.

    Is the customer running the EDID script every time the device is reset or powered off? The internal EDID memory is volatile and will need to be reloaded. 

    Best,

    Jack

  • 0 in reply to Jack Scherlag
    TI__Expert 6155 points

    Hi Jack,

    We set the 0x18 in the script after we found the script did not run at the first time. 

    Jack Scherlag said:
    Is the customer running the EDID script every time the device is reset or powered off?

    Yes. 

    Maybe it is because PC sends a timing that the TCON cannot suffer. How can we know the timing from PC? Or if you have any experience on PC - 949EVM system?

    Regards,

    Peter

  • 0 in reply to Peter Xu
    TI__Mastermind 34515 points

    Hi Peter,

    What are the MODE_SELs set to on the 949? For HDMI compliant devices, the EDID from the source will be read whenever the HPD signal is asserted. If the new EDID is written after the PC has already read the default 949 EDID, then the source will not retransmit the new timing.

    The MODE_SEL option that allows the user to load in custom EDID before HDMI initialization is EXT_CTL. If EXT_CTL is set, then the HDMI initialization will not continue until the user turns control over to the internal state machine.

    Peter Xu said:
    Maybe it is because PC sends a timing that the TCON cannot suffer.

    The PC is not able to see the TCON. The PC only interacts with the 949 via the HDMI protocol.

    Best,

    Jack

  • 0 in reply to Jack Scherlag
    TI__Mastermind 34515 points

    Hi Peter,

    When I checked the EDID I saw that the option for sRGB color space was turned on. Can you check if the display needs sRGB?

    Attached is an EDID that doesn't use sRGB color space.

    0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x06, 0xAF, 0xD4, 0x12, 0x00, 0x00, 0x00, 0x00,
 0x00, 0x17, 0x01, 0x04, 0xA0, 0x3D, 0x3D, 0x78, 0x00, 0xDA, 0x94, 0x91, 0x54, 0x59, 0x97, 0x27,
 0x19, 0x4E, 0x54, 0x00, 0x00, 0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0xD2, 0x19, 0x00, 0x20, 0x50, 0x10, 0x16, 0x30, 0x14, 0x14,
 0x36, 0x00, 0xD8, 0x01, 0x00, 0x00, 0x00, 0x18, 0x00, 0x00, 0x00, 0x0F, 0x00, 0x00, 0x00, 0x00,
 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00, 0xFE, 0x00, 0x41,
 0x55, 0x4F, 0x0A, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x00, 0x00, 0x00, 0xFE,
 0x00, 0x42, 0x31, 0x30, 0x31, 0x45, 0x41, 0x4E, 0x30, 0x31, 0x2E, 0x32, 0x20, 0x0A, 0x00, 0xCB

    Best,

    Jack

  • 0 in reply to Jack Scherlag
    TI__Expert 6155 points

    Hi Jack,

    Please see the datasheet for " LVDS to DSI" device.[DELETED]

    They are still testing the new EDID.

    Regards,

    Peter

  • 0 in reply to Peter Xu
    TI__Mastermind 34515 points

    Hi Peter,

    I looked through the LVDS to DSI datasheet. I didn't see anything in particular that would cause an issue with display color.

    The other EDID option that can be explored are the chromaticity coordinates. The display datasheet might have information on this.

    Best,

    Jack

  • 0 in reply to Jack Scherlag
    TI__Expert 6155 points

    Hi Jack,

    The system is still abnormal when using the EDID you gave us. I will onsite debug with them next week. Is there any other point that I should check?

    Regards,

    Peter

  • 0 in reply to Peter Xu
    TI__Mastermind 34515 points

    Hi Peter,

    Check the display datasheet/settings to see if there is anything we need to program in the EDID.

    Best,

    Jack

  • 0 in reply to Jack Scherlag
    TI__Expert 6155 points

    Hi Jack,

    Today I went to customer's lab and debugged with them. I found their MAPSEL was wrong and EDID not totally right. Then I revised their setting. The problem was fixed. Thanks for your support.

    Regards,

    Peter

  • 0 in reply to Jack Scherlag
    TI__Expert 6155 points

    Hi Jack,

    Please move the thread to internal forum since I uploaded the schematic and datasheet.

    Regards,

    Peter

  • 0 in reply to Peter Xu
    TI__Mastermind 34515 points

    Hi Peter,

    I cannot move this thread to internal. Refer to this thread in the E2E you upload to the internal forum so it gets assigned to me.

    Best,

    Jack