--- /dev/null
+module top(input clk,
+ //#input btn,
+ output green_led_d7,
+ output orange_led_d8,
+ output red_led_d5,
+ output yellow_led_d6
+ );
+ localparam ctr_width = 24;
+ localparam ctr_max = 2**ctr_width - 1;
+ reg [ctr_width-1:0] ctr = 0;
+ reg [9:0] pwm_ctr = 0;
+ reg dir = 0;
+ reg btn = 0;
+
+ always@(posedge clk) begin
+ ctr <= dir ? ctr - 1'b1 - btn: ctr + 1'b1 + btn;
+ if (ctr[ctr_width-1 : ctr_width-3] == 0 && dir == 1)
+ dir <= 1'b0;
+ else if (ctr[ctr_width-1 : ctr_width-3] == 7 && dir == 0)
+ dir <= 1'b1;
+ pwm_ctr <= pwm_ctr + 1'b1;
+ end
+
+ reg [9:0] brightness [0:7];
+ localparam bright_max = 2**10 - 1;
+ reg [7:0] led_reg;
+
+ genvar i;
+ generate
+ for (i = 0; i < 8; i=i+1) begin
+ always @ (posedge clk) begin
+ if (ctr[ctr_width-1 : ctr_width-3] == i)
+ brightness[i] <= bright_max;
+ else if (ctr[ctr_width-1 : ctr_width-3] == (i - 1))
+ brightness[i] <= ctr[ctr_width-4:ctr_width-13];
+ else if (ctr[ctr_width-1 : ctr_width-3] == (i + 1))
+ brightness[i] <= bright_max - ctr[ctr_width-4:ctr_width-13];
+ else
+ brightness[i] <= 0;
+ led_reg[i] <= pwm_ctr < brightness[i];
+ end
+ end
+ endgenerate
+
+ // assign led = led_reg;
+ assign green_led_d7 = led_reg[0];
+ assign orange_led_d8 = led_reg[1];
+ assign red_led_d5 = led_reg[2];
+ assign yellow_led_d6 = led_reg[3];
+
+endmodule