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chaitusvk
Participant
Participant
298 Views
Registered: ‎02-15-2019

Does VGA source and VIDEO To AXI should be in same clk domain..

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HI @

i am newbie to VIDEO processor , i want Time stamp on video , In my design i have VGA source that generate Time in video which will be mixed with master video stream 

To mix these stream i want to convert VGA to axi Screenshot from 2021-03-19 14-48-25.png

my VGA source is running at 25MHZ at 640x480  my system is working fine 

But when i changed the AXI clk to 100MHZ keeping VGA source and VTC at 25mhz my system is not working 

I checked with ILA my AXI stream is fine , SImulation is also fine 

Any one please help me whether VGA source can run at diffrent frequency from AXI ..

 

Screenshot from 2021-03-19 16-06-00.png

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reaiken
Explorer
Explorer
275 Views
Registered: ‎07-18-2011

@chaitusvk 

It looks like you have your Video In to AXI4-Stream IP configured for common clock mode instead of independent clock mode.   

You need to configure it for independent clock mode, and connect the video clock to the vid_io_in_clk input and connect your higher frequency AXI clock to the aclk input.

Your AXI4-Stream to Video out IP needs to be configured for independent clock mode as well.

Also, on your VTC, connect the video clock to the clk input, and the AXI clock to the s_axi_aclk input (if you are using the AXI4-Lite Interface).

Basically, all input-side clocks run on the input video clock, all output-side clocks run on the output clock, and everything in the middle runs on the higher-frequency AXI clock. 

The AXI clock can also be a lower frequency than the video clocks if you convert the video to 2 or more pixels per clock. 

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reaiken
Explorer
Explorer
276 Views
Registered: ‎07-18-2011

@chaitusvk 

It looks like you have your Video In to AXI4-Stream IP configured for common clock mode instead of independent clock mode.   

You need to configure it for independent clock mode, and connect the video clock to the vid_io_in_clk input and connect your higher frequency AXI clock to the aclk input.

Your AXI4-Stream to Video out IP needs to be configured for independent clock mode as well.

Also, on your VTC, connect the video clock to the clk input, and the AXI clock to the s_axi_aclk input (if you are using the AXI4-Lite Interface).

Basically, all input-side clocks run on the input video clock, all output-side clocks run on the output clock, and everything in the middle runs on the higher-frequency AXI clock. 

The AXI clock can also be a lower frequency than the video clocks if you convert the video to 2 or more pixels per clock. 

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chaitusvk
Participant
Participant
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Registered: ‎02-15-2019

Thank @reaiken

 

@reaiken  thank you so much ...

I am able to generate video ,

But overlay video is  changing its position  or running many times  main video is running at 148.5MHZ and overlay video is running at 25 MHZ , i enclosed the video clip , Please help me how to avoid this running frame 

 

 

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reaiken
Explorer
Explorer
187 Views
Registered: ‎07-18-2011

@chaitusvk 

You have to synchronize your overlay source and incoming video source to the output frame rate.

This is typically done by using a triple-buffer in memory for the video input sources and synchronizing the read side and the overlay with a vertical interrupt from the output VTC.

If the overlay is already generated using timing from the output VTC, the overlay synchronization step is not necessary, just the incoming video needs to be synchronized because it is from a different clock/frame rate.

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