Saturday, July 14, 2012

vga


It is a wonderful day because I have figured out the vga timer once again.  
The problem probably had something to do with the PES clock.
The first few moments, the output would be undefined.  The
screen I tested on probably saw that undefined ness and put up
a flag that said "problem" and refused to work.  After I took
care of that problem it all started to work.  Its funny how that little 
small start of undefined signal messed everything up.

Another thing that contributed to the problem was that the h counter and
v counter were not counting at the right time.  The v counter should 
increment when ever the h counter was reset to zero.  But for some 
reason, it would increment when h counter reached 400.  

These two problems were eventually solved.  The first one was solved 
by modifying the pes_clock such that  clock_out was given its value soon
after starting up.  It used to have to wait until the process reached its 
max count before giving it a value.

The second was solved by making the the v counter count on the
falling edge of the v_clk.  Even though it gave a warning during synthesis
all I care is that it works.

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