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Explorer
Explorer
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Registered: ‎02-18-2013

Stucking with understanding of Video Timing and AXI4-Stream to Video Out

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Hello,

I have this video design working for me 

Video.png

The AXI4-Stream runs with 40 MHz. So I get an 800x600 pixel image.

But this solution doesn´t work with AXI-Stream @ 100 MHz and generating the clock for the video timing controller from a clocking wizard (I use the clocking wizard to convert a 125 MHz clock into a 40 MHz clock which I have connected with the clk-Pin of the video timing controller - the rest doesn´t get changed).

It seems that the Video Out IP doesn´t generate a locked signal because the LED doesn´t light up. Does anybody have an idea why this doesn´t work with 40 MHz external from the DCM and 100 MHz AXI-Stream?

 

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Explorer
Explorer
670 Views
Registered: ‎02-18-2013

Hello,

thank you, but I only forgot that the timing generator doesn´t produce a pixel clock, so you have to take care that the clock of the Video Out IP and die VGA clock needs to be similar. In this case 100 MHz input clock for the Video Out IP with 800x600 pixel doesn´t work if the timing controller produce a 40 MHz clock.

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Teacher
Teacher
696 Views
Registered: ‎06-16-2013

Hi @kampi 

 

It is not enough information to reply it.

Would you reply the following question ?

 

- How do you change the parameter on VTG ?

  - According to your tcl file, it seems that you didn't change it.

- Do you want to work fine at 100MHz on AXI4Stream ?

  - If yes, what board or device do you use ? If Zybo, it might be difficult to archive 100MHz on AXI4 Stream.

- What is target resolution ?

- Why are there some input floating ports ?

 

BTW, I suggest you to make sure status signal on "AXI4Stream to video output" IP.

 

Best regards,

 

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Explorer
Explorer
671 Views
Registered: ‎02-18-2013

Hello,

thank you, but I only forgot that the timing generator doesn´t produce a pixel clock, so you have to take care that the clock of the Video Out IP and die VGA clock needs to be similar. In this case 100 MHz input clock for the Video Out IP with 800x600 pixel doesn´t work if the timing controller produce a 40 MHz clock.

View solution in original post

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Explorer
Explorer
653 Views
Registered: ‎07-18-2011

@kampi 

You should set your AXI4-Stream to Video Out IP clock mode to independent, then run your AXI clock at 100MHz and your AXI4-Stream to Video Out vid_io_clock and VTC clk  pins at the video pixel frequency, and the AXI4-Stream to Video Out axi_clock pin at the 100MHz AXI clock frequency.

This will allow you to run any output frequency independent of the AXI clock frequency, as long as the output frequency is lower than the AXI clock frequency.  If the output pixel clock frequency needs to be higher than your max AXI clock frequency, you can run your IP at 2 or 4 pixels per clock.

 

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