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Original question:

DS90UB941AS-Q1: white display issue

DS90UB941AS-Q1: In Splitter mode, can we configure the parameters(Hsync Front Porch, Hsync Width, etc ) for each FPD link?

chen zh
Intellectual 300 points
Part Number: DS90UB941AS-Q1

Dear TI:

       Can we configure these like configure in pattern test?  We met one issue , UB941 -> two UB948, and only one display is ok, so we want to configure port[x] for each FPD link.

BRs,

Arvin

  • 0
    TI__Guru** 103215 points

    Hello Chen,

    Can you please share the full panel timing parameter spec for both panels including the tolerances? There is some limited adjustment capability for the timing parameters in splitter mode, but not full control so if you share the timing parameters, then I can help you figure out if there is a method to meet the timing of both panels 

    Best Regards,

    Casey 

  • 0 in reply to Casey McCrea
    Intellectual 300 points

    Hi Casey:

        Please check the following parameters, Thanks.

  • 0 in reply to chen zh
    TI__Guru** 103215 points

    Hello Chen,

    The above seems to show only one panel spec but you mentioned there are two panels connected through 941AS. Can you share the timing for both panels? 

    Also is the above showing only one half of the horizontal timing (one OLDI channel?) It looks like a 1920x720 panel size if I were to double the Hactive. 960x720 is a relatively uncommon panel size 

    Best Regards,
    Casey 

  • 0 in reply to Casey McCrea
    Intellectual 300 points

    Hi Casey:

        It's same panel. 

        And for your doubt about size,  you're right. It's 1920*720...

  • 0 in reply to chen zh
    TI__Guru** 103215 points

    Hello Chen,

    So you are trying to drive two identical 1920x720p panels? Can you also provide the timing information for the superframe which you are providing to 941AS which contains both images and the 941AS device configuration?

    Best Regards,

    Casey 

  • +1 in reply to chen zh
    TI__Guru** 103215 points

    Hello Chen,

    Here's my understanding of the current system you have:

    1x DSI -> 941AS -> 2x 948 -> each display 1920x720@60 with PCLK = 96MHz 

    The timing parameters for each display are as follows:

    HACT = 1920

    HFP = 64

    HSYNC = 32

    HBP = 32

    VACT = 720

    VFP = 45

    VSYNC = 8

    VBP = 8

    PCLK = 96MHz 

    In order to generate a superframe to support 2x of these screens, then the source image must have 2x the horizontal timing for each parameter in side by side 3D format and 2x the PCLK of the video for each screen, so that would mean that the DSI source image should have the following dimensions:

    HACT = 3840

    HFP = 128

    HSYNC = 64

    HBP = 64

    VACT = 720

    VFP = 45

    VSYNC = 8

    VBP = 8

    PCLK = 192MHz 

    Then you can run the following example code to init the 941AS to drive the two screens:

    # 3840x720@60 Symmetric Split Example - 2x 1920x720@60

# Video 0 and Video 1 Parameters:
# HACT = 1920
# HFP = 64
# HSYNC = 32
# HBP = 32
# VACT = 720
# VFP = 45
# VSYNC = 8
# VBP = 8
# PCLK = 96MHz 

# DSI Superframe Dimensions:
# HACT = 3840
# HFP = 128
# HSYNC = 64
# HBP = 64
# VACT = 720
# VFP = 45
# VSYNC = 8
# VBP = 8
# PCLK = 192MHz 

# DSI clock = 576MHz
# DSI Lane Speed = 1152Mbps/lane 
# 4 Lanes DSI
# DSI input port 0

import time

UB941AS = 0x18

board.WriteI2C(UB941AS,0x01,0x02) # Reset
time.sleep(0.1)
board.WriteI2C(UB941AS,0x01,0x08) # Disable DSI
board.WriteI2C(UB941AS,0x1E,0x01) # Select port 0

board.WriteI2C(UB941AS,0x4F,0x8C) # 4 Lane Mode continuous clock

board.WriteI2C(UB941AS,0x5B,0x07) # Splitter mode

board.WriteI2C(UB941AS,0x40,0x04) # TSKIP_CNT
board.WriteI2C(UB941AS,0x41,0x05) # TSKIP_CNT
board.WriteI2C(UB941AS,0x42,0x40) # TSKIP_CNT

board.WriteI2C(UB941AS,0x56,0x80) # L/R Pixel Processing
board.WriteI2C(UB941AS,0x32,0x80) # Set 2D Line Size 1920
board.WriteI2C(UB941AS,0x33,0x07) # 

board.WriteI2C(UB941AS,0x1E,0x01) # Select port 0: 1920x720
board.WriteI2C(UB941AS,0x36,0x00)
board.WriteI2C(UB941AS,0x37,0x80) # X Start = 0
board.WriteI2C(UB941AS,0x38,0x7F) 
board.WriteI2C(UB941AS,0x39,0x07) # X Stop = 1919
board.WriteI2C(UB941AS,0x3A,0x00)
board.WriteI2C(UB941AS,0x3B,0x00) # Y Start = 0
board.WriteI2C(UB941AS,0x3C,0xCF)
board.WriteI2C(UB941AS,0x3D,0x02) # Y Stop = 719

board.WriteI2C(UB941AS,0x1E,0x02) # Select port 1: 1920x720
board.WriteI2C(UB941AS,0x36,0x00)
board.WriteI2C(UB941AS,0x37,0x80) # X Start = 0
board.WriteI2C(UB941AS,0x38,0x7F) 
board.WriteI2C(UB941AS,0x39,0x07) # X Stop = 1919
board.WriteI2C(UB941AS,0x3A,0x00)
board.WriteI2C(UB941AS,0x3B,0x00) # Y Start = 0
board.WriteI2C(UB941AS,0x3C,0xCF)
board.WriteI2C(UB941AS,0x3D,0x02) # Y Stop = 719

board.WriteI2C(UB941AS,0x40,0x10) # Init DSI Clock Settings (From Section 10.2 of datasheet)
board.WriteI2C(UB941AS,0x41,0x86) # Init DSI Clock Settings (From Section 10.2 of datasheet)
board.WriteI2C(UB941AS,0x42,0x0A) # Init DSI Clock Settings (From Section 10.2 of datasheet)
board.WriteI2C(UB941AS,0x41,0x94) # Init DSI Clock Settings (From Section 10.2 of datasheet)
board.WriteI2C(UB941AS,0x42,0x0A) # Init DSI Clock Settings (From Section 10.2 of datasheet)

board.WriteI2C(UB941AS,0x01,0x00) #Release DSI

    Best Regards,
    Casey