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ADV7604 autographics and TriLevel Sync

Question asked by HaraldA on Oct 6, 2011
Latest reply on Nov 1, 2011 by DaveD

Hi,

 

I am trying to implement component video to the ADV7604 and needs to use Autographics mode. I have the system working and get a picture through the chip. However I have problems with sync processing and clamping of the incoming signal.

 

I feed the chip with a 720p@60Hz YPbPr signal. The Y signal is also fed to the SYNC0 input for sync on Y slicing. As per the standard 720p, the Y signal carries embedded trilevel sync. Using the predefined mode, the chip seems to extract the sync correctly. However, when I use autographics mode (which I have to do because of legacy code and proprietary signals) I get the slicer to work, but it seems to slice the sync as if it is a normal sync on green type of sync. This means that the output is off by a sync width and that the automatic clamping functions starts to clamp the signal in the positive part of the tri-level sync. Adjusting the slice level does not change the trigger position at all.

 

1. Is there any way to tell the ADV7604 to expect trilevel syncs, not default to bi level SOG type of slicing (negative edge instead of positive)?

2. For autographics mode, do I need to set the clamping position manually, or will the chip find a clamping position? To me it seems like the CP_ANVC_POS_START[13:0] and CP_DFC_POS_START [13:0] must be set even if I'm using the internal clamp signal.

3. The Tri-x inputs is not used for sync slicing? My understanding is that these inputs are used to detect the level of some additional digital signal levels found in scart and D-conn and is not applicable for component YPbPr.

 

Thanks.

 

Best regards,

Harald Antonsen

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