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TE0726-04 ZynqBerry + zhdmi HDMI core issue

Started by zerkman, October 26, 2024, 09:25:19 PM

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zerkman

Hello,

I've been lent a newly purchased TE0726, rev. 04 ZynqBerry board. I am trying to run my open source zhdmi HDMI transmitter core on it.

The problem is that I haven't been able to have the zhdmi demo running properly. It seems the output is incorrect HDMI, with the blue component getting the same levels as the red component. The audio is not playing correctly: the expected 440 Hz sine wave can be heard, but with many crackles.

My HDMI capture device does not recognise the signal, so I had to take a picture of the screen:
test-zynqberry.jpg

The correct image should be:
test-z7lite.png
(as captured from another board).

The demo project to obtain this display can be created as follows:
git clone https://github.com/zerkman/zhdmi
cd zhdmi/demo/vivado
VIVADO=/opt/Xilinx/Vivado/2024.1/bin/vivado ./create_project.sh zhdmi_demo_zynqberry
Of course, use the real path to your installed copy of Vivado.
I used Vivado 2024.1, but it should also work with other versions.

I believe I used the proper pin assignment constraints, as borrowed from one of the TE0726 demos.

Am I doing something wrong? Could someone try and tell me if they can reproduce the issue?

zerkman

After further investigation, it appears the hdmi_tx_d_p
  • and hdmi_tx_d_n
  • output ports (blue component) are physically swapped.

I worked around the issue by inverting the input data bits for the TMDS serialiser of the blue component, and now I'm getting correct image and sound. No idea if it can easily be fixed on the Xilinx HDMI IP core.

Is it a known issue on the TE0726? Maybe only on revision 4?



zerkman

Sorry I meant hdmi_tx_d_p[ 0 ] and and hdmi_tx_d_n[ 0 ] are swapped.