tut4 with strobe, stuck at the last transition

fsm-tut4/rtl/top.v

@@ -19,7 +19,7 @@ module top(i_clk, o_led, o_led_row_0, i_request, o_busy);
    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 strobe;
    reg busy_buf;
    wire req_buf;
 
@@ -30,8 +30,8 @@ module top(i_clk, o_led, o_led_row_0, i_request, o_busy);
 
    initial begin
       led_buf = 6'h0;
-      // {strobe, counter} = 0;
+      {strobe, counter} = 0;
-      counter = 0;
+      // counter = 0;
       state = 0;
       busy_buf = 0;
    end
@@ -45,26 +45,26 @@ module top(i_clk, o_led, o_led_row_0, i_request, o_busy);
    // counter and strobe run only during busy signal is High
    always @(posedge clk_12MHz) begin
       if (busy_buf)
-         counter <= counter + 1'b1;
+         // counter <= counter + 1'b1;
-         // {strobe, counter} <= counter + 1'b1;
+         {strobe, counter} <= counter + 1'b1;
       else
-         // {strobe, counter} <= 0;
+         {strobe, counter} <= 0;
-         counter <= 0;
+         // counter <= 0;
    end
 
    // state change once strobe starts
    always @(posedge clk_12MHz) begin
       if (!busy_buf && req_buf)
          state <= 4'h1;
-      else if (state >= 4'hB)
+      else if (state >= 4'hB && strobe)
          state <= 4'h0;
-      else if (state != 0)
+      else if (state != 0 && strobe)
          state <= state + 1'b1;
    end
 
    // fsm for led_buf
    always @(posedge clk_12MHz) begin
-      // if (strobe)
+      if (strobe)
          case (state)
             4'h1: led_buf <= 6'b00_0001;
             4'h2: led_buf <= 6'b00_0010;