ADV7280 seems to stop conversion on signal loss

Hi, we've an ADV7280 EVAL board with parallel output connected to a i.MX6Q running Android 8.0.

The CVBS single ended signals are correctly acquired and using I2C commands we can switch the inputs as the user needs.

When, on the selected channel, the signal is disconnected for a few seconds and then riconnected, in the status register 0x10 there's the value 0x0F and the i.MX6 can't receive data anymore.

In this situation we resend the initalization script to ADV7280 but nothing change (always 0x0F in status tregister).

Any suggestion? Thank you, kind regards.

Luca

  • +1
    •  Analog Employees 
    on Oct 20, 2020 10:55 AM 1 month ago

    Hi,

    Please make sure with below things,

      Analog Devices does not have a part that can feed two CVBS inputs simultaneously to the iMX6.

      The ADV728x devices can only display one CVBS input at a time.

    ADV7280 can only process one CVBS input at a time. It can switch from one input to another but even in "fast switch mode" this can take up to 250 ms. So please try with fast switch script and let us know, Here you can speed up the lock time by forcing the video format using the fast switch script.

      Fast Switch Mode- ADV728x 

    Please note that here ADV7280 / ADV7280-M Design Support Files  you will find recommended scripts that are needed to program the ADV7280. You will also find applications note AN-1337 with covers most of the issues that customers encounter when interfacing the ADV728x-M family of parts with MIPI receivers.

    Thanks,

    Poornima

  • Hi Poornima, we're using the I2P Fast Switch PAL script (version 4.5)  but we send it to ADV7280 only the first time.

    To switch between channels we change only the value of register 0x00.

    Now resending the script every time we switch channel the system seems to work fine (a bit slower , with about 500ms for signal lock).

    Thank you for your support, kid regards.

    Luca

  • +1
    •  Analog Employees 
    on Oct 22, 2020 9:01 AM 1 month ago in reply to Luca_Bruni

    Hi,

    By default the part sacrifices switching time for robustness in the face of low quality signalling. Here we have attached a presentation about fast switching script.

    ADV7180_Fast_switching.pdf

    Also plesae note that If you are switching from a single ended CVBS input to differential CVBS (or YC or YPbPr) inputs, perform a software reset, wait 10 ms and then program the ADV7280 with a recommended differential CVBS script ( or YC script or YPbPr script).

    Thanks,

    Poornima