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Registered: ‎03-03-2017

HDMI TX simply forward ref-clk to HDMI CLK pins?

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Hi,

   I am using an HDMI TX setup in a Kintex-7 device using Vivado/SDK 2018.1 successfully, but the user is requesting I give them an option to simply set the HDMI Tx CLK pins to the ref-clk frequency and not worry about any data on the R/G/B lanes of the HDMI.

   Is there any kind of settings in the software driver for the HDMI TX that would allow this to happen? 

   When I open the implementation I see the ref-clk goes into a PLLE2_ADV and the PLLE2_ADV clkout1 output drives the HDMI clock pins.   I was hoping there was a way to simply enable this path where the PLLE2_ADV.clkout1 is equal to the PLLE2_ADV.clkin1 pin (i.e. the ref-clk).

   I know this is a special request and would never be used in a typical video application, but would be really helpful for our internal application.

Thanks.

Tim

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Registered: ‎03-03-2017

回复: HDMI TX simply forward ref-clk to HDMI CLK pins?

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Thanks all for the responses.

We decided to go another route.   Since we did not need HDMI video signals for our end product, we only needed the HDMI clock diff pair to be running at a specific frequency, I tore out all HDMI from the FPGA design and instead but buffers between our oscillator (Si598) and the HDMI clock pins diff-pair.   That seems to be working for our needs.

Tim

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Registered: ‎08-01-2007

回复: HDMI TX simply forward ref-clk to HDMI CLK pins?

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Can you have a look at Figure 3‐3: GTXE2 on PG230 December 5, 2018, which should help to answer your question?

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Registered: ‎03-03-2017

回复: HDMI TX simply forward ref-clk to HDMI CLK pins?

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@nathanx ,

   Thanks for the response.   I do already understand the HW setup which is what your referenced figure shows.   What I am wondering is if the SW driver has a mode where I can turn on the HDMI output clock pins without worrying about setting up everything else.

Tim

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Registered: ‎08-01-2007

回复: HDMI TX simply forward ref-clk to HDMI CLK pins?

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The question is to simply set the HDMI Tx CLK pins to the ref-clk frequenc, do you want to set the GT reference clock frequency of HDMI TX or the other video clocks, if it's HDMI TX video clock, it's possible. see the xvphy_hdmi.v file in SDK installation directory.

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Registered: ‎03-03-2017

回复: HDMI TX simply forward ref-clk to HDMI CLK pins?

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Thanks all for the responses.

We decided to go another route.   Since we did not need HDMI video signals for our end product, we only needed the HDMI clock diff pair to be running at a specific frequency, I tore out all HDMI from the FPGA design and instead but buffers between our oscillator (Si598) and the HDMI clock pins diff-pair.   That seems to be working for our needs.

Tim

View solution in original post

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