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DS90UB926Q-Q1: Generic pattern auto scrolling configuration problem

Patrick Brunner
Prodigy 60 points
Part Number: DS90UB926Q-Q1
Other Parts Discussed in Thread: ALP

Hi team

I have some issues while configuring a serializer and deserializer (DS90UB926QSQE and DS90UB925QSQE) chip. They are connected together over the FTP III link with no parallel input and no DE, HS, VS and PCLK signal on the input of the serializer. I want to put a generic auto scrolling pattern to the output of the deserializer all with internal clock configuration. A 320x240 TFT-display is connected to the deserializer and RGB-888 (24-Bit) is used. Both chips are connected directly to the same I2C-Bus so I have access to both chips directly to configure them.

So far I did the following configurations:

Setup timing control of the serializer (Address 0x0C):

All this registers were set over the indirect registers and checked by a read out.

-       Register 0x03   Data 0x20

-       Register 0x04   Data 0x98

-       Register 0x05   Data 0x61

-       Register 0x06   Data 0x10

-       Register 0x07   Data 0x40

-       Register 0x08   Data 0x01

-       Register 0x09   Data 0xF0

-       Register 0x0A   Data 0x20

-       Register 0x0B   Data 0x04

-       Register 0x0C   Data 0x24

-       Register 0x0D  Data 0x0F

-       Register 0x0E   Data 0x00 

This Setup shall result in the following configuration:

-       Horizontal resolution     320

-       Horizontal sync            32

-       Horizontal front porch 20

-       Horizontal back porch 36

-       Vertical resolution         240

-       Vertical sync                4

-       Vertical front porch       3

-       Vertical back porch      15

 

Setup of the pattern generator and auto scrolling of the serializer (Address 0x0C)::

All this registers were set over the indirect registers and checked by a read out.

-       Register 0x0F   Data 0xF0

-       Register 0x10   Data 0x0E

-       Register 0x11   Data 0x21

-       Register 0x12   Data 0x43

-       Register 0x13   Data 0x65

-       Register 0x14   Data 0x87

-       Register 0x15   Data 0xA9

-       Register 0x16   Data 0xCB

-       Register 0x17   Data 0xED

 

Setup config of the serializer (Address 0x0C)::

All not listed registers should have the default value!

-       Register 0x12   Data 0x20

-       Register 0x14   Data 0x06

-       Register 0x64   Data 0x30

-       Register 0x65   Data 0x05

 

Setup config of the deserializer (Address 0x2C)::

All not listed registers should have the default value!

-       Register 0x65   Data 0x05

 

To start the pattern generator I just put 3.3V to the OEN and OSS_SEL pins and set the following register of the deserializer  (Address 0x2C)::

-       Register 0x64   Data 0x31

Before configuring the chips the display is only black/grey (backlight on). After configuring all registers as described above I can see an auto rotating generic pattern of white, black, red, green and blue full-screen. These are the first generic patterns. In the registers I set the auto scrolling function to use all 15 patterns (Register 0x10   Data 0x0E). What I expect is to see are the 15 auto generic patterns on the display auto rotating.

Why are only the first 5 patterns visible? 

Do I have to change any other registers values?

Best regards,

Patrick Brunner




  • 0
    TI__Mastermind 25955 points

    Hi Patrick,

    Looking into this - a few questions:

    How many fixed patterns are you able to see when you cycle through them manually by changing pattern generator select (from 0001 through 1110)?

    Are there any patterns that don't display for you when auto-scrolling mode is not enabled?

    Sincerely,

    Bryan Kahler

  • 0 in reply to Bryan Kahler
    Prodigy 60 points

    Hi Bryan

    It seems, that something is strange. First I tried to disable the pattern generator at all by clearing bit 0 of register 0x64 (Write 0x30 to register 0x64) first on the serializer and then on the deserializer. The full-screen pattern white, black, red, green and blue full-screen is still visible.

    Then I tried to disable the auto scrolling function by clearing bit 0 of register 0x65 (Write 0x04 to register 0x64) first on the serializer and then on the deserializer, but the same pattern is still visible.

    As a last point I re-enabled the pattern generator by writing 0x31 to the register 0x64 first on the serializer and then on the deserializer. Now the screen is blank/white.

    Can you explain that behavior?

    Best regards,

    Patrick Brunner

  • 0 in reply to Patrick Brunner
    TI__Mastermind 25955 points

    Hi Patrick,

    This is unexpected behavior from the description of the steps above.

    Could you please read back the register 0x64 on both devices to confirm that the register is truly clearing?  After writing 0x30 to 0x64, please read back the value to ensure it set properly.

    When writing 0 to bit 0 of 0x64, the pattern generator should be disabled.

    Sincerely,

    Bryan Kahler

  • 0 in reply to Bryan Kahler
    Prodigy 60 points

    Hi Bryan

    I agree, according to the datasheets it seems to be unexpected behavior for me too.

    I once again did the whole process as I described above and I read back the register 0x64. The value is the same as I programmed: 0x30. The behavior is still the same. So there must be another issue.

    Best regards,

    Patrick Brunner

  • 0 in reply to Patrick Brunner
    TI__Mastermind 25955 points

    Hi Patrick,

    The deserializer pattern generator has priority over the serializer pattern generator.  The set up appears to be on the serializer.  Please ensure everything is being configured for the serializer and the pattern generator enable is being sent to the serializer and not the deserializer.

    If this doesn't fix the issue, please send me your script from ALP with all the register writes and addresses included.

    Sincerely,
    Bryan Kahler