File size: 2,025 Bytes
9d6dd52 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 | module led_controller(
input wire clk, reset, pedestrian_button, car_sensor,
output reg [2:0] lights
);
localparam RED = 3'b001, YELLOW = 3'b010, GREEN = 3'b100;
localparam WAIT = 2'b00, GO = 2'b01, WARN = 2'b10, STOP = 2'b11;
reg [1:0] state, next_state;
reg [31:0] count;
initial begin
state = WAIT;
count = 0;
end
always @(posedge clk or posedge reset) begin
if (reset) begin
state <= WAIT;
count <= 0;
end else begin
state <= next_state;
if (count == 10) begin
count <= 0;
end else begin
count <= count + 1;
end
end
end
always @* begin
case (state)
WAIT: begin
if (car_sensor) begin
lights = RED;
next_state = GO;
end else begin
lights = YELLOW;
next_state = WARN;
end
end
GO: begin
if (count < 6) begin
lights = GREEN;
next_state = GO;
end else begin
lights = YELLOW;
next_state = WARN;
end
end
WARN: begin
if (count < 2) begin
lights = YELLOW;
next_state = WARN;
end else if (pedestrian_button) begin
lights = RED;
next_state = STOP;
end else begin
lights = RED;
next_state = GO;
end
end
STOP: begin
if (count < 4) begin
lights = RED;
next_state = STOP;
end else begin
lights = GREEN;
next_state = GO;
end
end
endcase
end
endmodule
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