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TMDS181: TMDS181 to TMDS181 can't linkup

Part Number: TMDS181

Hi, TI Team

    I have some questions  about TMDS181 with your help.I design one board that it supports one HMDI output (source) port and   one HMDI input (sink) port. The HDMI signal connect between FPGA and HDMI connector.These HDMI siganls use TMDS181 retimer chips .

If FPGA load the software of input HDMI and the HDMI input port connect to computer with HDMI cable,the HDMI can linkup;

If FPGA load the software of output HDMI and the HDMI input port connect to  the display of hdmi with HDMI cable,the HDMI can linkup;

however,If  input HDMI port of one board  connect to  output HDMI port of another board  with HDMI cable,the HDMI link down. The hdp (source and sink) can snoop,but the input side  of HDMI dispaly that

the RX  mode is DVI.

Hardware configuration:

1.choose pin strap mode;

2、pin17 SIG_ EN 64.9k up to gnd

3、PIN 20 PRE_ SEL floating

4、PIN36 TX_ TERM_ CTL floating

Can you give  mie some ideas to  solve this problem?

HDMI Schematic.pdfHDMI Board Diagram.pdf

  • Hi,

    1. Please check the pullup on the DDC for the source and sink side. The source side needs to be 2k while the sink side needs to 47k

    2. On the sink side, does the FPGA load up its EDID info, and then drive its HPD high?

    3. Do you have a I2C protocol analyzer that you can use to snoop the DDC bus and verify the data on the DDC bus matches with the sink's EDID?

    4. For TMDS181, please make sure SCL_SRC and SDA_SRC are tied to ground when not being used.

    Thanks

    David