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Altera_Forum
Honored Contributor I
1,064 Views

DE10-Lite Video problem drawing a pixel

Hi, I'm making a project for my university and I'm working on a Videogame with a DE10-Lite. 

I'm trying to get the video processing working and everything is fine except one problem: 

 

If I try to draw the 0,0 pixel with a color containing a blue signal (Blue component different from 0) the video goes crazy and everything starts flickering 

 

If I draw a red or yellow color on 0,0 everything is fine. As long as the Blue bits of the pixel 0,0 are set to 0 it works. 

 

Here you can see: 

 

No blue on 0,0 pixel and the video is fine: 

https://ibb.co/dwmdty 

 

I put 0x0001 on the 0,0 pixel and madness happens: 

https://ibb.co/gwpmgj 

 

I'm using a 16 bit Pixel buffer with DMA reading SDRAM linked with other video IPS. The output signal goes to a VGA monitor. 

 

Here is the embedded system built with Qsys: 

https://alteraforum.com/forum/attachment.php?attachmentid=15340&stc=1  

 

If I draw blue on the 0,0 pixel, even the video signal coming from the char buffer is heavily disturbed. I can't manage to understand what could be causing the problem. 

 

Any help is appreciated, thanks.
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4 Replies
Altera_Forum
Honored Contributor I
81 Views

Hi, 

 

It may be synchronization or timing issue. 

 

1. Monitor the vsync, hsync & blank period. 

2. Give different values on the 0,0 pixel and see whether you are facing the same issue. 

 

Best Regards, 

Anand Raj Shankar 

(This message was posted on behalf of Intel Corporation)
Altera_Forum
Honored Contributor I
81 Views

 

--- Quote Start ---  

Hi, 

 

It may be synchronization or timing issue. 

 

1. Monitor the vsync, hsync & blank period. 

2. Give different values on the 0,0 pixel and see whether you are facing the same issue. 

 

Best Regards, 

Anand Raj Shankar 

(This message was posted on behalf of Intel Corporation) 

--- Quote End ---  

 

 

Than you Anand Raj Shankar for your answer, 

I will check the h_sync, v_sync and blank signals as soo as I can go to the lab. 

 

Meanwhile I can tell you that I set the Clocked Video Output module like this: 

 

https://alteraforum.com/forum/attachment.php?attachmentid=15343&stc=1  

 

disp_clk is a clock signal @25 MHz from the PLL 

 

I wish to use a 640x480(60 Hz) format. Is there anythik wrond with it? 

 

Best regards, Dario B.
Altera_Forum
Honored Contributor I
81 Views

 

--- Quote Start ---  

 

If I draw a red or yellow color on 0,0 everything is fine. As long as the Blue bits of the pixel 0,0 are set to 0 it works. 

 

..... 

I put 0x0001 on the 0,0 pixel and madness happens: 

https://ibb.co/gwpmgj 

 

Any help is appreciated, thanks. 

--- Quote End ---  

 

 

Hi Dario, in first thank to pointing me to this problem I can possibly connect to an unknown behaviour of my project. 

I face similar problem on an LCD, all IP but DMA video buffer are mine, I use same IP you are using from University programme to fetch video stream from memory then feed my core. 

Sorry to say I am proficient on VHDL and that IP is Verilog written. On that core I'm impaired by language I don't manage in deep. 

From your second image I can infer, as other wrote to you, some garbling on HSynk and Vsynk are supposed to be the trouble but internal DMA unlock to frame can be too, synk tend to have fuzzy image with left border unstable, frame unlock tend to have good raster with worst image. From single still picture is quite impossible diagnose which one is on place. 

Please can you repost image 2 best focused plus a short video of what happen. 

Best regards 

Roberto
Altera_Forum
Honored Contributor I
81 Views

I solved the issue changing the output video IP with "VGA controller". This means it had to be the "video clocked output" IP (maybe parameters were wrong). 

 

Thank you for the replies anyway! 

 

Dario B.
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