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Altera_Forum
Honored Contributor I
1,084 Views

Sync signal of VIP Clocked Video Input

Hey guys, 

 

Just one quick question about the sync signals of Clocked Video Input megacore: 

 

The manual said vid_h_sync should be set to 1 when video is in horizontal synchronization period. But what is the horizontal synchronization period here? Is it Front porch, Back porch, Sync pulse or Active Sample? Thanks very much!
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5 Replies
Altera_Forum
Honored Contributor I
41 Views

vid_h_sync is only referring to the horizontal synchronization period and not the blanking period. 

 

If you read the section on Separate Synchronization Format it hints that vid_h_sync is strictly the horizontal synchronization period, and does not include the blanking periods. This can be seen further through the timing diagram, where the h_sync pulse is asserted between the two vid_datavalid sections. The vid_datavalid indicating active picture period. 

 

The documentation could be more explicit on this.
Altera_Forum
Honored Contributor I
41 Views

Thanks for your reply. I have just gone over the manual. Just to double confirm: 

the horizontal data flow is: H front porch -> H Sync -> H back porch -> pixel data, and then repeat itself. 

 

h_sync is asserted during "H Sync" only; and vid_datavalid is asserted during "pixel data" only. Is that correct?  

 

Thanks very much! 

 

 

 

 

--- Quote Start ---  

vid_h_sync is only referring to the horizontal synchronization period and not the blanking period.
Altera_Forum
Honored Contributor I
41 Views

That is correct. The h_sync signal is not asserted during the front porch or back porch periods of the horizontal blanking period, and the vid_datavalid is asserted during the active picture time.

Altera_Forum
Honored Contributor I
41 Views

Did you get this running? I am running into a issue trying to create a test pattern into the Clocked Video Input. The clocked video input is set to 800x600. What is the front porch and back porch settings and sync timing you used? 

 

Thanks
Altera_Forum
Honored Contributor I
41 Views

I was using 640x480, and I got it working. 

The timing info I used comes from the link below:  

http://tinyvga.com/vga-timing 

 

The key is that either "Sync pulse" or "Sync pulse + Front porch + Back porch" should be set as blank period. Sorry I forgot which setting I was using. But you should be able to figure it out after trying both. :o
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