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unstable video output from adv7850 when doing VGA 1600x1200 60hz

Question asked by jps3 on Sep 10, 2014
Latest reply on Sep 23, 2014 by jps3

hello,

 

we are using a adv7850 with 2 VGA inputs. The 7850 output is connected to the input of a adv7626.

 

when we do 1600x1200, 60hz(DMT standard format), the 7850 detects the format correctly & we write the vid_std(0x16) for that resolution. The problem is that on the 7626, we see de regen & sometimes vert. lock interrupts triggering. There is either no video output from the 7626 or its unstable(flickers & intermittent).

 

we have no issue doing many other VGA resolutions. Also, this same format over hdmi is stable - its only an issue with VGA inputs

 

are there some magic bits/register settings that need to be applied for this to work?

 

we have current products that use the adv7842 & have no problem with this vga format.

 

thanks,

John

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