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VGA problem in Verilog
von Xavier P. (Company: PUCMM) (xavi07p)

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Hello.

I have the the Pong Game code in Verilog with FPGA Xilinx Spartan 
Basys2.
Everything works well, but I notice some flickering in the monitor, 
something like vibrations. What do you think? What is the problem? Maybe 
noisy clock?
Thank you.

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Re: VGA problem in Verilog
von Sigi (Guest)

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In general, it's impossible to answer without your source code.
But the Basys2 is well known in e.g. classic fpga computing for
it's bad clock, more exactly, it's a jitty oscillator. This is
often the source of pixel jittering.
AFAIK the board has an 8-pin socket for an extra clock source.

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Re: VGA problem in Verilog
von Verilogi (Guest)

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if there is a pll used, the clock should be fine. small clock problems 
usually lead only to bad pixels. if there is flickering, a bad 
constellation between hsynch and vsynch is given usually

most probably also a unsynched updating process of the screen will be 
the problem to solve

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