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Forum: FPGA, VHDL & Verilog Display binary image on vga using VHDL


von ElectroCataru (Guest)



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Hello,

How can i get rid of the lines? I just wanna display "PONG" text.

Thanks.

von FPGA NOTFALLSEELSORGE (Guest)


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1. Too few information given.

2. Wild guess:

The Image is stored in blocks. The addressing of the image memory lags 
behind or the data is behind and so for some clocks old data is being 
put on the lines.
But it is strange that the lines are on both sides of the caracters. 
Something went horrible wrong.

Did you do simulation? What if you just output a white rectangle, is 
that ok?
How is the signal path inside the FPGA, where is the image stored, how 
do you output it and what external electronics is involved? Is it 
classic VGA or do you just mean the resolution and it is HDMI/DP/...?

Is the Image supposed to look green? Where is the original image? Maybe 
the lines are an artistic sideeffect?

von Lothar M. (lkmiller) (Moderator)


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ElectroCataru wrote:
> How can i get rid of the lines?
First is to find out: where do they come from?

> How can i get rid of the lines?
Are they static? Or do they change?

> I just wanna display "PONG" text.
On what platform with what hardware?

> I just wanna display "PONG" text.
Where does this "PONG" text come from?
Do you have 5 bitmaps of those 5 characters somewhere in memory?

von ElectroCataru (Guest)


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Are they static? Or do they change?

are static

On what platform with what hardware?

using a basys 3 and a 1024x768 monitor


Do you have 5 bitmaps of those 5 characters somewhere in memory?

i use this site https://www.dcode.fr/binary-image to convert a photo 
(jpg) in binary.

von ElectroCataru (Guest)


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FPGA NOTFALLSEELSORGE wrote:
> 1. Too few information given.
>
> 2. Wild guess:
>
> The Image is stored in blocks. The addressing of the image memory lags
> behind or the data is behind and so for some clocks old data is being
> put on the lines.
> But it is strange that the lines are on both sides of the caracters.
> Something went horrible wrong.
>



> Did you do simulation? What if you just output a white rectangle, is
> that ok?
> How is the signal path inside the FPGA, where is the image stored, how
> do you output it and what external electronics is involved? Is it
> classic VGA or do you just mean the resolution and it is HDMI/DP/...?
>

classic VGA, with bitmap


> Is the Image supposed to look green? Where is the original image? Maybe
> the lines are an artistic sideeffect?

yes, it's supposed to look green.

von Lothar M. (lkmiller) (Moderator)


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ElectroCataru wrote:
>> Are they static? Or do they change?
> are static
You have the traditional "off-by-one" problem due to latency.


> i use this site https://www.dcode.fr/binary-image to convert a photo
> (jpg) in binary.
Try out some test patterns: half black/half white with top/bottom and 
left/right. Try vertical/horizontal lines with one pixel width. Or any 
other repeating pattern like squares or hatches.

Try to find out a behaviour and dig this out in simulation.

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