Intel® FPGA University Program
University Program Material, Education Boards, and Laboratory Exercises

UP VGA Pixel Buffer

Honored Contributor II



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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