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ADV7280-M Unstable/Abnormal video image

Category: Datasheet/Specs
Product Number: ADV7280ABCPZ M
Software Version: None

Dear Sir,

We study ADV7280-M on our system.

It happen the following symptom.

-Symptom: It sometimes happen abnormal image

Normal image/Color Bar

Abnormal image/Color bar

 

-Occuring rate :1/ 500 to 1000 times

-Set-up sequence on ADV7280

 Power on(3.3V ->1.8V) --> HW Reset(wait 5msec) > settng Software reset by I2C(Wait 5msec) -> Setting other register by I2C

*I2C speed: 100kHz

-We take care of  'AN1337' for MIPI CSI-2 issue.

<Others>

It set "Software Reset" then setting other register when it happne abnormal.

- It is improved, (receover to normal image.)

<Quuestion and advice>

Could you please advise which register are related wth this symptom if you have similar symptom?

We think that MIPI output is no problem and this symptom is related with PLL setting timing. 

Thanks and Best regards

Kida

  • Hi,

    Kindly make sure with the below points.

    1. Check whether the crystal / oscillator is outputting 28.63636MHz.
    2. Check if the FSC_lock bit (User Map register 0x10 bit[2]) is high. This bit indicates that the ADV7280 has locked correctly to the color subcarrier.
    3. You can disable or change the threshold for the color kill function. The color kill function forces the ADV7280 into black and white or grey output if the amplitude of the color subcarrier is too small

                Refer the respective bits in the ADV728x hardware manual.

                CKE, Color Kill Enable, Address 0x2B[6]
                CKILLTHR[2:0], Color Kill Threshold, Address 0x3D[6:4]

    1. Adaptive contrast enhancement (ACE) block offers improved visual detail by using an algorithm to automatically vary the contrast levels to enhance picture detail. The ACE function is disabled by default. Please refer Page49 for more details in https://www.analog.com/media/en/technical-documentation/user-guides/ADV7280_7281_7282_7283_UG-637.pdf

    Also, please ensure that you are using the latest ADI recommended scripts.

    Note: ADV728x may not work for poor video signals.  If the color burst is below that percentage of the standard's value then the color will be killed, this will happen due to weak signal. If the color subcarrier is below 14.275mVpp, then the ADV7280 will not be able to lock to the color subcarrier and it will output a black and white image.

     

    Thanks,
    Dharani S