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ADV7180 & ADV7173 Interconnect Problems

Question asked by Fehnrir on Apr 9, 2011
Latest reply on Apr 16, 2011 by Fehnrir

For a project in which I wanted to test the video decoding abilities of the ADV7180 by sending the digital video to a video decoding chip, ADV7173.


My setup consists of the basic setup in the ADV7180 datasheet (pg 107 - Mode 1 CVBS Input (Composite Video on Ain1)).  I've setup the ADV7173 based on the recommended NTSC setup but with a modification (ADV7180 by default outputs field instead of VS, so the timing register was changed accordingly, along with the genlock/subcarrier frequency lock signal input enabled).  I've setup the genlock between the two chips and that removed the horiztontal jitter.  I've verified that the I2C works (since the output wouldn't do anything without being set up and changing of the registers in the chips results in change to the output video).


ADV7180 ----------- ADV7173

!(#HSYNC)        -> HS                       (Horizontal sync signal)

FIELD/#VSYNC -> FIELD/#VSYNC    (used as a field signal)

SFL                  -> SCRESET/RTC    (genlock signals)

p[7:0]                -> p[7:0]                  (Pixel data)


The good news: I've gotten video output that looks like the input video. No image scrolling, no color changes, everything looks fine except...


The bad news: On top of the video signal that is output, I've got what appears to be a thin grey-ish bar that scrolls up the screen.  It is constant.


I've hooked up a oscilloscope to the composite input and output signals.  At a glance, the output signal has a slightly larger amplitude and more noisy (I dunno if that is due to the filtering/gain due to the chips or actually noise).


I have got a few ideas why this might be not working.  The ADV7180 outputs a Line-Locked Output Clock (LLC) signal that seems that it should be used (possibly drive the clock of the output chip?).  I was also thinking of trying to use VSYNC instead of FIELD as well (may fix or do nothing). Or that my dev board a poor layout and the noise is due to that (doubtful, but there is a possibility that it is true).


Layout: (Included is a pdf schematic of my development hardware)

Composite In (Playstation 1 - a classy video source, if I do say it myself) -> ADV7180 (40-Lead LFCSP) -> FGPA directly wiring between ADV7180/ADV7173 -> ADV7173 (48-Lead LQFP) -> Composite Out (to TV/oscilloscope)


Any insight or ideas would be great.


EDIT: The pages of the schematic with the layout of the ADV7180 and ADV7173 are the last two.