In our application, image data is written into the RAM via a DMA and read out in a loop over a VDMA and output via HDMI.
Everything works fine, but we noticed when viewing a generated test pattern (simple color ramps) that periodically (every 16 pixel) incorrect colors are displayed in the green channel. The saved reference images are correct. In addition, the error only occurs in horizontal ramps, not in vertical.
One possible cause is the splitting of the green value in 2 packets during data transmission in DDR mode to the ADV7511 (see ADV7511 Hardware user's guide p. 30). The whole issue looks like a timing problem for us. So we tried to solve the issue with constraining the setup and hold times or changing the clock delay in ADV7511 registers. So far without success.
Does anyone have an idea what it could be or possible solutions?
Dump1.jpg shows the original image in the ram
DSC_4880.JPG is the photo from output on a display
Hi
are you using similar design as there:
https://wiki.trenz-electronic.de/display/PD/HDMI+Design
what resolution, ref clock?
at 720p we have not seen bad pixels yet.
if you use are ready made images, are then the colors correct?
The problem exist independent from the resolution, we tested it at 720p and 1080p with the same result.
The design is simimal like this: https://wiki.trenz-electronic.de/display/PD/HDMI+Design, onl the TPG does not exist in our block deign.
I've replaced the Select_wizard_io DDR block with the video_io_to_hdmi_1.0 but the problem still exists.
Thank you
geimel
1 can you add TPG and check if the colors from TPG are also wrong?
2 does OUR design with TGP show correct colors on same monitor?
After adding the TPG, the TPG colors in green channel are wrong too.(horizontal ramp test pattern)
The grayvalue with the problem is only there, when the 4 lower bit of the green channel turn to zero. This is the case if the value turns from 255 to 0, from 15 to 16, from 31 to 32 and so on.
In the Trenz reference design this problem does not exist.
maybe you forgot to set the output slew rate to fast?
All hdmi outputs (data, clock, syncs) are set to slew fast.
Which voltage is recommend VCC25?
yes 2.5V
currently I an glueless, at our bench it seems really work without issues.
Is this issue solved?
The problem is not 100% solved,
when I init the ADV7511 first time, there are no Stripes.
When I reinit the ADV without a reset, there are stripes.