AnsweredAssumed Answered

ADV7842 Sync-on-Green Detect

Question asked by wood0201 on Jul 20, 2011
Latest reply on Aug 4, 2011 by DaveD

Our board needs to support RGsB.  I set up a test case using the analog SXGA to DVI output script I got from AVES.  When I connected my video source register 0x44 (CP) 0xB5 read 0x81.  I thought it would read 0x83 to indicate an embedded sync was seen.  So then I set 0x44 (CP) 0x85 to 0x1B which manually set the sync selection to embedded sync.  At this point my DVI output appeared correctly on my monitor.  I read 0x44 (CP) 0xB5 and it returned 0x83 which is correct because an embedded sync was present.  But then I removed my source and read 0x44 (CP) 0xB5 again and it still read 0x83 which is incorrect because an embedded sync was no longer present.  So in summary I have the two questions below:


1) Why do I have to manually set the sync source to embedded sync to get my setup to output video?  I thought the auto detect mode was capable of recognizing embedded sync.


2) How can I determine if an RGsB source is present because 0x44 (CP) 0xB5 doesn't seem to accurately report embedded sync activity?


Incidentally, I read another post about sync-on-green problems and the need to pull down HSYNC and VSYNC inputs in order to make embedded sync functionality work properly.  I did so and it didn't have any impact on what I described above.