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Luminance Processing Control #1 Register on TVP5154A

Omin Chou
Genius 3555 points
Other Parts Discussed in Thread: TVP5154A, TVP5154

Hi all,

I used DM642+TVP5154A to do AVM application.

But I found some sets that appeared abnormal status on CH2 when did . After dumped YUV image from DM642 CCDC side, I could make sure the problem occurred on TVP5154A.

The problem was I removed camera and re-connected camera again at the run time. Only CH2 video went to abnormal status. It became low quality and flicker appearance. Then I dumped TVP5154 registers to find when changed value from 0x20(abnormal) to 0x60(default) on "Luminance Processing Control #1 Register". The video would go back to the normal status. But I did the hot-plug again, the video became worse again. Then I wrote the value from 0x60(default) to 0x20(abnormal). The video went back to normal status again.

So, I could not base on this strange state to do a work around. Could someone please give me some hints to handle this unstable state? Thanks in advance.

B.R.

OC

  • 0
    TI__Mastermind 43875 points

    As a test try forcing the video standard for the channel rather than allowing auto-switch.

    The control bit which is changing can only be changed by one of two ways. First, if the video standard of the analog video is detected as changing between, say, PAL and NTSC then this bit might change. Second, I2C programming of this register.

    Make sure that your I2C interface is not accidentlly changing this register, either through noise on the I2C lines or through incorrect program flow. If possible, once the TVP is initially configured, try disconnecting the I2C SCL signal from the TVP and see if the same result occurs (i.e. bad video).

    Make sure that the analog video signal at the TVP video input pin is correct. It is possible that there is a bad signal reaching the TVP input pin.

    Have you tried multiple OCBs or do you only see the iss ue on one system?

    BR,

    Steve

  • 0 in reply to Steve Clynes
    Genius 3555 points

    Hi Steve,

    Aimed at I2C noise concern, I did some test as follows.

    1. After initialized TVP5154, I would set 0xFE to 0x00 for disable all decoder channel to access via I2C.

    2. Tried to enable 0xFE. Then write address 0x00 to 0x20 and read back 0x00 to get 0x20 value.

    3. Did not change 0xFE state. Then write address 0x00 to 0x20 and read back 0x00 to get 0x00 value.

    So, this result could prove I2C noise should not impact tvp5154 state, right? Or you still intensely to disconnect I2C SCL signal? Thanks in advance.

    B.R.

    OC 

  • 0 in reply to Omin Chou
    TI__Mastermind 43875 points

    Why are you writing the value 0x20 to address 0x00? This is an invalid register write since bits 4-7 are reserved.

    Please try the previously mentioned tests, i.e. force the video format to NTSC, i.e. set register 0x28 = 0x02 and see if the issue still occurs.

    Many registers are automatically updated based on the currently detected video standard.

    BR,

    Steve

  • 0 in reply to Steve Clynes
    Genius 3555 points

    Hi Steve,

    Sorry to let you misunderstand my words. I just used an example to express my meaning.

    Here was my actual initial setting on TVP5154. 

    ==========

    0xFE = 0F

    0x7F = 00

    delay 2ms

    0xFE = 0F

    0x02 = B2

    0x00 = 00

    0x03 = 09

    0x0D = 07

    0x16 = 7C

    0x07 = 20

    0x17 = 1B

    0x15 = 81

    0x28 = 02

    0x09 = 8C 

    0x0C = 8C 

    0x0A = 8C 

    0x1B = 17 

    0x08 = 08 

    0xFE = 00 

    ==========

    B.R.

    OC

  • 0 in reply to Omin Chou
    TI__Mastermind 43875 points

    OK, understood.

    Please still try the force format test to see if this stops the luma register becoming corrupt.

    BR,

    Steve