This code have bch error.

[AndyDengChina]

This code have bch error.

[zerkman]

Are you using Vivado ? Which FPGA are you targeting ?

Please give the steps you followed to reproduce that error.

[AndyDengChina]

Thank you for your reply,

FPGA : ARTIX7 XCA7A35T-2FGG484C
VIVADO 2023.1
HDMI receiving device prompt: ChecksumErrOrBCHParityErr

[zerkman]

Thank you for reporting this. I must find a way to check this myself and try and fix this.

[zerkman]

I have performed various checks in the BCH and parity encoding, and I did not find any evident error. The different users are not reporting any similar errors.
However, I have recently encountered an issue on one specific board, whose HDMI output has part of its TMDS channels' differential pairs swapped for routing optimization reasons. This is equivalent to a logic NOT operation on such channels. This obviously causes signaling errors and also incorrect image display. This could also be the problem with your setup.

The zhdmi demo should display an image like this one:

If nothing is displayed, or if some of the RGB components on the display are incorrect, this could indicate that the HDMI output has some inversion on some channels.
The recent commits on this repository enable an INVERTED_TX generic bitfield which allows you to specify which TMDS channels are inverted. With this information the HDMI transmitter is able to invert back the corresponding channel values.

Please let me know if this is helpful to you.

[AndyDengChina]

HDMI sink prompt: ChecksumErrOrBCHParityErr
But the HDMI sink can display video normally.

[zerkman]

Can you explain what your HDMI sink is exactly? Is it a debugging device?
Could you make it produce additional information to narrow the search for the issue?

Also could you try inverting the clock signal by setting the INVERTED_TX generic to "1000" ?

[AndyDengChina]

Thank you for your patient guidance

hdmi sink ic : MTK TSUSV56

Could you make it produce additional information to narrow the search for the issue?
-- NO

Also could you try inverting the clock signal by setting the INVERTED_TX generic to "1000" ?

   Is it possible to modify here?

serial_clk: entity zhdmi.tmds_serializer port map (
	clk => clk,
	sclk => sclk,
	reset => reset,
            --tmds_d => "1111100000",   
	tmds_d => "0000011111",
	tx_d_n => tx_clk_n,
	tx_d_p => tx_clk_p
);

[zerkman]

Thank you for the information. I haven't found any useful information on this sink device.

Did you try using another display / HDMI sink ?
Does your display work correctly using other HDMI sources ? (computer, game console etc)?

About the clock inversion, you need the latest commit of ZHDMI:

$ cd zhdmi
$ git pull

You can see an example in demo/hdl/zhdmi_demo_top_zynqberry.vhd. On this example INVERTED_TX is set to "1001" so the clock and blue component signals are inverted. This is due to the fact the TMDS P/N pairs of the HDMI output are physically swapped on this board, and it is not possible, on Xilinx FPGAs, to just swap the pair assignment in the constraint file, for ouput pin pairs that are set as TMDS outputs. The only seemingly possible option is to logically invert the input bits for the corresponding TMDS transmitters.

If you set INVERTED_TX to "1000" only the clock component will be inverted. From left to right, the different bits correspond to the clock, red, green and blue TMDS pairs. If the colors look correct on your display, there should be no need to invert the RGB components.

[zerkman]

Oh, it is TSUMV56, not TSUSV56. Is it on the same board as the XC7A35T, or a separate one? Is there a datasheet for TSUMV56 available somewhere?

[AndyDengChina]

I didn't use any other HDMI SINK,
There is no such error message when using other HDMI sources
I still have the same issue with setting INVERTED_TX to "1000"
XC7A35T and TSUMV56 are designed on one PCB board
TSUMV56 is a chip from Taiwan, and the datasheet are not written in detail
I have his datasheet, but I can't send it to the Internet.
But I can send the datasheet to your email.

[zerkman]

Ok, please send the datasheet to my email (the address is on my git commits). It may help me understand what is going on.

[AndyDengChina]

I have sent an email to: [email protected]

But the email was not sent successfully, please let me know email address

[zerkman]

You can send it to [email protected]