Sequential Devices have
STATES!!
Which brings us to the
PROGRAM to WRITE.
There are several languages
that one can use.
THE PROGRAM CUPL HAS FOUR PARTS. [You will type the program in a TEXT processor, and save it with the *.pld extension. ]
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1. Header info [name, device format: leave Device and Format, make NAME same as your file]
2. Inputs: clock and maybe one other
3. Outputs: you have 2 states and 7 LED pins
4. LOGIC:
A. You have to name your states
B. You have to give the present/next/out equations
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Name scroll;
Device G22V10;
Format j;
/** Inputs */
Pin 1 = Clock;
Pin 2 = Stop;
/** Outputs **/
pin [14..15] = [Q1..Q0];
pin 16 = a;
pin 17 = b;
pin 18 = c;
pin 19 = d;
pin 20 = e
pin 21 = f;
pin 22 = g;
field count = [Q1..Q0];
$define S0 'b' 00
$define S1 'b' 01
$define S2 'b' 10
$define S3 'b' 11
/** Logic Equations */
Sequenced scroll {
present S0 next S1 out a,b,c;
present S1 next S2 out b,c,d;
present S2 next S3;
present S3 next S0; }
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Once you type the program as myfile.pld, the remaining steps:
1. Compile using the CUPL compiler [which is on all computers in LAB]. The compiler will generate a *.jed file, -- which will have the ONES/ZEROES that you'll need.