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Altera_Forum's avatar
Altera_Forum
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13 years ago

lcd display

hi i'm beginner to vhdl. i'm write a vhdl code to display characters on lcd using de2 board. it display different characters for different input from 000 to 111. i'm already compile the code in q...
Altera_Forum's avatar
Altera_Forum
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13 years ago

You don't have any delay in your code. For example in this line

db<=x"4D",x"41",x"58",x"49",x"4D",x"55",x"4D",x"20 ",x"5A",x"4F",x"4E",x"45";
the synthesizer will just see that you assign all those values to db successively with no delay, and will just simplify it to
db<=x"45";

You need to add a clock input to your process and do things in sequence, for example by using a state machine, a counter to know which data word to send next, and possibly another counter to implement delays. The LCD datasheet should tell you how much you will need to wait between two states.