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Department of Microelectronic Systems, Faculty of Electronics,
Telecommunications and Informatics, Gdansk University of Technology
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Counter in Gray code
Task:
Design 2-bit Gray code counter.
Inputs:
- button BTN0 simulating clock
(signal's name - clk_i),
- button BTN3 asynchronous reset
(signal's name - rst_i).
Outputs:
- LED LD0 - bit 0
(signal's name - led_o(0)),
- LED LD1 - bit 1 (signal's name
- led_o(1)).
Clock is generated by consecutive pushing the button BTN0
and due to this switch bouncing can be observed (generation of more than
one slope after single pressing the button).
Functional simulation has to be run and the circuit has to be practically
verified by programming the prototype board.
UCF file, Digilent Spartan-3 board, Spartan-3 3S200 FT256-4:
# Push-buttons:
NET "rst_i" LOC = "L14" ; # pressed high BTN3
NET "clk_i" LOC = "M13" ; # pressed high BTN0
# pin M13 is not dedicated to clock, so force it:
NET "clk_i" CLOCK_DEDICATED_ROUTE = FALSE;
# LEDs:
NET "led_o<0>" LOC = "K12" ; # high on
NET "led_o<1>" LOC = "P14" ; # high on
