struct

Help/presentation_examples/led_walk/src/verilog/counter.v

@@ -0,0 +1,71 @@
+`timescale 1ns/1ps
+`default_nettype none
+
+// Simple counter_reg with synchronous reset (and no load)
+// 
+
+module counter #(
+    parameter WIDTH = 8,
+    parameter INITIAL_VALUE = 8'h0f
+) (
+    input wire clk,     // global clock
+    input wire reset,   // synchronous reset signal
+    input wire en,      // enable signal
+    output reg strobe   // output strobe
+);
+
+initial strobe = 0;
+
+reg[WIDTH-1:0] counter_reg = INITIAL_VALUE;
+
+always @(posedge clk) begin
+    if (reset) begin
+        counter_reg <= INITIAL_VALUE;
+    end 
+    else if (en) begin
+        strobe <= 0;
+        if (counter_reg == 0) 
+            counter_reg <= INITIAL_VALUE;
+        else begin
+           if (counter_reg == 1) 
+               strobe <= 1;
+           counter_reg <= counter_reg - 1;
+        end
+    end
+
+end
+
+`ifdef FORMAL
+
+reg f_past_valid = 0;
+
+always @* f_past_valid = !$initstate;
+
+always @* begin
+    assume (counter_reg <= INITIAL_VALUE);
+end
+
+always @(posedge clk) begin
+    // if ($initstate) begin
+    //     assume(counter_reg==INITIAL_VALUE);
+    // end
+//    if (!$initstate && $past(en)==1 && !$past(reset)) begin
+    if (f_past_valid && $past(en)==1 && !$past(reset)) begin
+        if (counter_reg < INITIAL_VALUE) 
+            assert (counter_reg == $past(counter_reg) - 1);
+        else begin
+            assert(counter_reg == INITIAL_VALUE && $past(counter_reg)==0);
+        end
+    end
+end
+
+`endif
+
+
+`ifdef VERIFIC
+//internal_check: assert property (@(posedge clk)(counter_reg==11)|=>(counter_reg==10));
+//assert property (@(posedge clk)(counter_reg==11 && en && !reset)|=>(counter_reg==10));
+`endif
+
+    
+endmodule

Help/presentation_examples/led_walk/src/verilog/led_walk.v

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+`timescale 1ns/1ps
+`default_nettype none
+module led_walk #(
+    parameter CLK_SPEED = 27_000_000,
+    parameter NBLEDS = 5
+)
+(
+    input wire clk,
+    output reg [NBLEDS-1:0] led
+);
+
+wire strobe;
+
+localparam ONE_HALF_S = CLK_SPEED / 2;
+localparam ONE_S = CLK_SPEED ;
+localparam TWO_S = CLK_SPEED *2;
+
+
+localparam TIME = TWO_S;
+localparam TIME_WIDTH = $clog2(TIME);
+
+initial led = {NBLEDS{1'b1}};
+
+counter  #(.WIDTH(TIME_WIDTH), .INITIAL_VALUE(TIME)) counter_inst
+(
+    .clk(clk),
+    .reset(1'b0),
+    .en(1'b1),
+    .strobe(strobe)
+);
+
+
+
+// State machine to cycle through LEDs
+reg [$clog2(NBLEDS)-1:0] current_led; // Tracks the current LED index
+
+always_ff @(posedge clk) begin
+    if (strobe) begin
+        // Turn off all LEDs and turn on the next one in the cycle
+        led <= {NBLEDS{1'b1}};
+        led[current_led] <= 1'b0;
+
+        // Move to the next LED in the cycle
+        if (current_led == NBLEDS - 1)
+            current_led <= 0;
+        else
+            current_led <= current_led + 1;
+    end
+end
+
+endmodule

Help/presentation_examples/led_walk/src/verilog/led_walk_top.v

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+module blink_top
+(
+    input wire clk,
+    output wire [5:0] leds
+);
+
+led_walk #(
+    .CLK_SPEED(27_000_000),
+    .NBLEDS(6)
+) lw_inst (
+    .clk(clk),
+    .led(leds)
+);
+
+endmodule