first commit

rtl/button_trigger.sv

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+module button_trigger # (
+	parameter CLOCK_FREQUENCY = 100_000_000,
+	parameter DEBOUNCE_MILLIS  = 40
+) (
+	input  logic clock,
+	input  logic reset,
+	input  logic raw_button,
+	output logic trigger_signal
+);
+	localparam DEBOUNCE_COUNTER_MAX = (CLOCK_FREQUENCY / 1000) * DEBOUNCE_MILLIS;
+
+	logic [$clog2(DEBOUNCE_COUNTER_MAX)-1:0] counter;
+	enum logic [1:0] { ST_IDLE, ST_FILTER, ST_RELEASE } state;
+	
+	always_ff @(posedge clock, posedge reset) begin
+		if(reset) begin
+			state <= ST_IDLE;
+			counter <= 'bx;
+			trigger_signal <= '0;
+		end else case(state)
+		ST_IDLE: begin
+			if(raw_button) begin
+				counter <= DEBOUNCE_COUNTER_MAX;
+				state <= ST_FILTER;
+			end
+		end
+		
+		ST_FILTER: begin
+			if(!raw_button)
+				state <= ST_IDLE;
+			else if(counter > 0)
+				counter <= counter - 1;
+			else begin
+				trigger_signal <= '1;
+				state <= ST_RELEASE;
+			end
+		end
+			
+		ST_RELEASE: begin
+			trigger_signal <= '0;
+			if(!raw_button)
+				state <= ST_IDLE;
+		end
+		
+		default: state <= ST_IDLE;
+		endcase
+	end
+
+endmodule