forked from tanchou/Verilog
Init et début de réflexion sur le projet
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`timescale 1ns/1ps
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module tb_ultrasonic_fpga;
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reg clk = 0;
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reg rst = 1;
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reg start = 0;
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reg echo = 0;
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wire trig_out;
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wire [8:0] distance;
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time t_start, t_end;
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// Clock 27MHz => periode = 37ns
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always #18 clk = ~clk;
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ultrasonic_fpga uut (
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.clk(clk),
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.rst(rst),
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.start(start),
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.echo(echo),
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.trig_out(trig_out),
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.distance(distance)
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);
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initial begin
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$dumpfile("ultrasonic.vcd");
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$dumpvars(0, tb_ultrasonic_fpga);
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// Reset
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#100;
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rst = 0;
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// Start
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#100;
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start = 1;
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#40;
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start = 0;
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wait (trig_out == 1);
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t_start = $time;
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// Attendre qu'il redescende
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wait (trig_out == 0);
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t_end = $time;
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$display("Trig HIGH duration: %0dns", t_end - t_start);
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if ((t_end - t_start) >= 9500 && (t_end - t_start) <= 10500) begin
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$display("Trigger signal is high for 10us.");
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#10;
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echo = 1;
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#5800;// Echo dure 5800ns (≈ 100 cycles @ 27MHz => ≈ 100 cm aller-retour)
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echo = 0;
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end else begin
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$display("Trigger signal is NOT high for 10us.");
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end
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#500;
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// Affiche la distance
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if (distance > 0) begin
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$display("Distance measured: %d cm", distance);
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end else begin
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$display("No distance measured.");
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end
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$finish;
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end
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endmodule
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@@ -0,0 +1,114 @@
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module ultrasonic_fpga #(
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parameter integer CLK_FREQ = 27_000_000 // Fréquence d'horloge en Hz
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)(
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input wire clk,
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input wire start,
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inout wire sig, // Broche bidirectionnelle vers le capteur
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output reg [15:0] distance, // Distance mesurée en cm
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output reg [2:0] state = IDLE
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);
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reg [15:0] trig_counter;
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reg [31:0] echo_counter;
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reg sig_out;
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reg sig_dir; // 1: output, 0: input
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assign sig = sig_dir ? sig_out : 1'bz;
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wire sig_in = sig;
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localparam IDLE = 3'd0,
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TRIG_HIGH = 3'd1,
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TRIG_LOW = 3'd2,
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WAIT_ECHO = 3'd3,
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MEASURE_ECHO = 3'd4,
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DONE = 3'd5,
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WAIT_NEXT = 3'd6;
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localparam integer TRIG_PULSE_CYCLES = CLK_FREQ / 100_000; // 10us pulse
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localparam integer DIST_DIVISOR = (58 * CLK_FREQ) / 1_000_000; // pour conversion us -> cm
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localparam integer MAX_CM = 350;
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localparam integer TIMEOUT_CYCLES = (MAX_CM * 58 * CLK_FREQ) / 1_000_000;
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localparam WAIT_NEXT_CYCLES = (CLK_FREQ / 1000) * 100; // 60 ms
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reg [31:0] wait_counter;
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always @(posedge clk) begin
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case (state)
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IDLE: begin
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sig_out <= 0;
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sig_dir <= 1;
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distance <= 0;
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if (start) begin
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state <= TRIG_HIGH;
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trig_counter <= 0;
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end
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end
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TRIG_HIGH: begin
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sig_out <= 1;
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sig_dir <= 1;
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if (trig_counter < TRIG_PULSE_CYCLES) begin
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trig_counter <= trig_counter + 1;
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end else begin
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trig_counter <= 0;
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state <= TRIG_LOW;
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end
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end
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TRIG_LOW: begin
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sig_out <= 0;
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sig_dir <= 0; // Mettre en entrée
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state <= WAIT_ECHO;
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end
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WAIT_ECHO: begin
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if (sig_in) begin
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echo_counter <= 0;
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state <= MEASURE_ECHO;
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end else if (echo_counter >= TIMEOUT_CYCLES) begin
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distance <= 0;
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state <= DONE;
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end else begin
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echo_counter <= echo_counter + 1;
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end
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end
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MEASURE_ECHO: begin
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if (sig_in) begin
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if (echo_counter < TIMEOUT_CYCLES) begin
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echo_counter <= echo_counter + 1;
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end else begin
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distance <= 0;
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state <= DONE;
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end
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end else begin
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distance <= (echo_counter * 1000) / DIST_DIVISOR;
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state <= DONE;
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end
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end
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DONE: begin
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if (start) begin
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wait_counter <= 0;
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state <= WAIT_NEXT;
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end else begin
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state <= IDLE;
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end
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end
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WAIT_NEXT: begin
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wait_counter <= wait_counter + 1;
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if (wait_counter >= WAIT_NEXT_CYCLES) begin
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state <= TRIG_HIGH;
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end
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end
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endcase
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end
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endmodule
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