use 1 Hz clock for visible walking

fsm-tut4/rtl/clk_gen.v

@@ -5,7 +5,25 @@ module clk_gen(
    output wire o_clk
 );
 
-assign o_clk = i_clk;
+// assign o_clk = i_clk;
+reg [31:0] counter;
+reg buf_clk;
+parameter CLK_RATE_HZ = 12_000_000;
+
+initial  begin
+   counter = 0;
+   buf_clk = 0;
+end
+assign o_clk = buf_clk;
+
+always @(posedge i_clk) begin
+   if (counter >= CLK_RATE_HZ/2 - 1) begin
+      counter <= 0;
+      buf_clk <= ~buf_clk; 
+   end
+   else
+      counter <= counter + 1;
+end
 
 endmodule
 // Local Variables:

fsm-tut4/rtl/top.v

@@ -8,18 +8,17 @@ module top(i_clk, o_led, o_led_row_0, i_request, o_busy);
    input wire i_request;
    output wire o_busy;
 
-   wire clk_12MHz;
+   wire clk_1Hz;
 
    clk_gen clk_gen_0 (/*autoinst*/
       // Outputs
-      .o_clk                 (clk_12MHz),
+      .o_clk                 (clk_1Hz),
       // Inputs
       .i_clk                 (i_clk));
 
    reg [WIDTH-1:0] counter;
    reg [3:0] state;
    reg [5:0] led_buf; // output buffer, take into account the icefun use active low LED
-   // reg strobe;
    reg busy_buf;
    wire req_buf;
 
@@ -30,30 +29,26 @@ module top(i_clk, o_led, o_led_row_0, i_request, o_busy);
 
    initial begin
       led_buf = 6'h0;
-      // {strobe, counter} = 0;
       counter = 0;
       state = 0;
       busy_buf = 0;
    end
 
-   always @(posedge clk_12MHz) begin
+   always @(posedge clk_1Hz) begin
       if (!busy_buf && req_buf)
          busy_buf <= 1;
       else
          busy_buf <= (state != 4'h0);
    end
    // counter and strobe run only during busy signal is High
-   always @(posedge clk_12MHz) begin
+   always @(posedge clk_1Hz) begin
       if (busy_buf)
          counter <= counter + 1'b1;
-         // {strobe, counter} <= counter + 1'b1;
       else
-         // {strobe, counter} <= 0;
          counter <= 0;
    end
 
-   // state change once strobe starts
+   always @(posedge clk_1Hz) begin
-   always @(posedge clk_12MHz) begin
       if (!busy_buf && req_buf)
          state <= 4'h1;
       else if (state >= 4'hB)
@@ -63,8 +58,7 @@ module top(i_clk, o_led, o_led_row_0, i_request, o_busy);
    end
 
    // fsm for led_buf
-   always @(posedge clk_12MHz) begin
+   always @(posedge clk_1Hz) begin
-      // if (strobe)
       case (state)
          4'h1: led_buf <= 6'b00_0001;
          4'h2: led_buf <= 6'b00_0010;
@@ -81,7 +75,7 @@ module top(i_clk, o_led, o_led_row_0, i_request, o_busy);
       endcase
    end
 
-`ifdef	FORMAL
+   `ifdef	FORMAL
       // state should never go beyond 13
       always @(*)
          assert(state <= 4'hd);
@@ -118,7 +112,7 @@ module top(i_clk, o_led, o_led_row_0, i_request, o_busy);
          // assert($onehot(o_led));
          // and avoided this case statement entirely.
       end
-`endif
+   `endif
 
 endmodule