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ADV7842 Sync & DE Output Polarity

Question asked by wood0201 on Jul 14, 2011
Latest reply on Jul 18, 2011 by DaveD

I have two seperate questions relating to ADV7842 sync and DE outputs.


1) When I have the ADV7842 setup to process incoming DVI I'd like it to output HS and VS with the same polarity as was received on the DVI.  For instance, incoming XGA has negative syncs so I'd like HS and VS to have negative polarity.  But incoming SXGA has positive syncs so I'd like HS and VS to have positive polarity.  I don't see a simple way to set the ADV7842 to do that though.  I can do it by having my micro constantly poll HDMI space (0x68) 0x05[5:4] to determine incoming sync polarity and then set IO space (0x40) 0x06[2:1] to match.  However, that is a crude solution.  Is there are way to configure the ADV7842 to pass the syncs with the same polarity as received?


2) My experimentation with DE polarity shows me the opposite functionality as stated in the software user guide.  When I set IO space (0x40) 0x06[3] to '0' I get positive DE polarity and when I set it to '1' I get negative polarity.  This is the opposite of what the documentation states.  Is there some other register that works in conjunction with this register or overrides it to set the DE polarity?