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UP VGA Pixel Buffer

Altera_Forum
Honored Contributor II
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Hi, 

 

I have a problem using the second Pixel Buffer. 

I'm using the SRAM at 0x0000000 for the first one 

and I have althoug configured the second one on 

this adress in the SOPC-Builder. 

 

Now I am manipulating the SRAM via some VHDL 

code, which I connect via the External Master to 

Avalon slave form the UP, which works fine. 

 

Now in NIOS I created an buffer, within SDRAM , 

and passed the adress to the VGA-Framebuffer as 

a the adress of the backbuffer, which also works fine, 

at least in the debug mode. 

 

But when I switch from first to second buffer, the adress 

in the VGA-Pixelbuffer switches correctly but on the 

screen nothing happens. 

 

What's kind of weird is that sometimes I only can see the 

Pixelbuffer stored in the SDRAM, but I can't find out how 

this happens The only way to restore is then to unplug the 

device from current. 

 

Although my alt_alarm functions don't seem to work might 

this be reason for my problem. 

 

Thanks a lot for your help 

 

Best wishes
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