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ADV7612 - changing video modes

Question asked by FAE@toronto2 on Mar 4, 2014
Latest reply on Mar 5, 2014 by tok

Hello,

 

I have a customer using an ADV7612 and they are noticing some inconsistent behavior...

 

There are cases when switching between video modes causes the output to the receiver to go down and come back up, sometimes with a different clock rate (if the video mode changes).

 

On some switches, the ADV7612 seems to get caught in a state where non-valid (garbled) video comes out. We notice the clock from the chip goes up/down and the frame timing has glitches (e.g. a frame valid goes up, then on the next line it goes down then comes back up, etc.). We have found that unplugging the HDMI cable for a few seconds and then plugging it back in often fixes the problem. Also, hitting the MAIN_RESET register also brings it back. Of course neither of these solutions is ideal...

 

Does anyone have any comments and/or ideas? Or can maybe explain the details or limitations of switching between video modes... to me it seems like the device is unable to lock onto the signal correctly but my assumption is this should self remedy itself after some time (even if it causes a glitch on the screen for some time, etc.) without manual intervention...

 

Please advise. Thank you.

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