// Debounce.v
module DEBOUNCE
(
input CLK, RESET_N, SWITCH, // inputs
output reg INTERRUPT // output
);
//// ---------------- internal constants --------------
parameter N = 12 ;
////---------------- internal variables ---------------
reg [N-1 : 0] q_reg; // timing regs
reg [N-1 : 0] q_next;
reg DFF1, DFF2; // input flip-flops
wire q_add; // control flags
wire q_reset;
//// ------------------------------------------------------
////contenious assignment for counter control
assign q_reset = (DFF1 ^ DFF2); // xor input flip flops to look for level chage to reset counter
assign q_add = ~(q_reg[N-1]); // add to counter when q_reg msb is equal to 0
//// combo counter to manage q_next
always @ ( q_reset, q_add, q_reg)
begin
case( {q_reset , q_add})
2'b00 :
q_next <= q_reg;
2'b01 :
q_next <= q_reg + 1;
default :
q_next <= { N {1'b0} };
endcase
end
//// Flip flop inputs and q_reg update
always @ ( posedge CLK )
begin
if(RESET_N == 1'b0)
begin
DFF1 <= 1'b0;
DFF2 <= 1'b0;
q_reg <= { N {1'b0} };
end
else
begin
DFF1 <= SWITCH;
DFF2 <= DFF1;
q_reg <= q_next;
end
end
//// counter control
always @ ( posedge CLK )
begin
if(q_reg[N-1] == 1'b1)
INTERRUPT <= ~DFF2;
else
INTERRUPT <= INTERRUPT;
end
endmodule
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