DS90UB941AS-Q1: The left-right offset is too large，how to resolve it. Thanks.

chen zh

Intellectual 300 points

Part Number: DS90UB941AS-Q1

Dear Ti:

We met one issue, please check the following show and the left offset is too large:

The related paramters(work normal at the pattern test):

............................................

uVisWidth = '1920'
uHsyncFrontPorch = '25'
uHsyncWidth = '16'
uHsyncBackPorch = '17'
uVisHeight = '720'
uVsyncFrontPorch = '45'
uVsyncWidth = '15'
uVsyncBackPorch = '18'
uPixelFreqInHz = '94706640'

....................................................

When i adjust the uHsyncBackPorch value in soc side and the display work abnormal. So i try to adjust the 0x6c register in UB941. When value is 0x70 and the position of display is ok, but the display become torn at the same time. In this situation, no matter how we modify display reference except uHsyncBackPorch and can't resolve this torn issue.

.................................................

0x6a , 0x80

0x6c, 0x70

Do you have some advise for this issue? Thanks a lot.

over 4 years ago

0 chen zh over 4 years ago

Intellectual 300 points

More question:

If 0x6c and 0x6b register is used(val(reg 0x6c) is 0x70(112), val(reg 0x6b) is 0x10(16)), then is the following formula true?

HFP In 941 = All pix one line(1920+16+17+25) - 112 - 16 - 1920= - 70,

That's why display shows torn?

0 Ben Dattilo over 4 years ago in reply to chen zh

TI__Mastermind 25765 points

Hi,

If your programmed timing parameters do not match the timing that transmitted by the SoC, this may cause the abnormal display. HFP is typically generated based on the rest of the timing parameters. For example:

HFP = THW - AHW - HBP - HSW

In your case:

THW = 1920 + 16 + 17 + 25 = 1978

When forcing HBP = 112, the THW changes as you noted. This will also change the target PCLK and the HFP. Can you confirm the timing on the SoC side and the timing on the UB941 side match?

Regards,

Ben Dattilo

0 chen zh over 4 years ago in reply to Ben Dattilo

Intellectual 300 points

Thanks Ben. Is HFP's minimum value 0? In this case, it could be minus 70...

BR,

Arvin

+1 Ben Dattilo over 4 years ago in reply to chen zh

TI__Mastermind 25765 points

Hi Arvin,

That is correct, HFP should not be a negative value.

Regards,

Ben

0 chen zh over 4 years ago in reply to Ben Dattilo

Intellectual 300 points

Thanks Ben

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DS90UB941AS-Q1: The left-right offset is too large，how to resolve it. Thanks.