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module top(input clk_pin, input btn_pin, output [7:0] led_pin, output gpio0_pin);
wire clk;
wire [7:0] led;
wire btn;
wire gpio0;
(* BEL="X0/Y35/PIOA" *) (* IO_TYPE="LVCMOS33" *)
TRELLIS_IO #(.DIR("INPUT")) clk_buf (.B(clk_pin), .O(clk));
(* BEL="X4/Y71/PIOA" *) (* IO_TYPE="LVCMOS33" *)
TRELLIS_IO #(.DIR("INPUT")) btn_buf (.B(btn_pin), .O(btn));
(* BEL="X0/Y23/PIOC" *) (* IO_TYPE="LVCMOS33" *)
TRELLIS_IO #(.DIR("OUTPUT")) led_buf_0 (.B(led_pin[0]), .I(led[0]));
(* BEL="X0/Y23/PIOD" *) (* IO_TYPE="LVCMOS33" *)
TRELLIS_IO #(.DIR("OUTPUT")) led_buf_1 (.B(led_pin[1]), .I(led[1]));
(* BEL="X0/Y26/PIOA" *) (* IO_TYPE="LVCMOS33" *)
TRELLIS_IO #(.DIR("OUTPUT")) led_buf_2 (.B(led_pin[2]), .I(led[2]));
(* BEL="X0/Y26/PIOC" *) (* IO_TYPE="LVCMOS33" *)
TRELLIS_IO #(.DIR("OUTPUT")) led_buf_3 (.B(led_pin[3]), .I(led[3]));
(* BEL="X0/Y26/PIOB" *) (* IO_TYPE="LVCMOS33" *)
TRELLIS_IO #(.DIR("OUTPUT")) led_buf_4 (.B(led_pin[4]), .I(led[4]));
(* BEL="X0/Y32/PIOD" *) (* IO_TYPE="LVCMOS33" *)
TRELLIS_IO #(.DIR("OUTPUT")) led_buf_5 (.B(led_pin[5]), .I(led[5]));
(* BEL="X0/Y26/PIOD" *) (* IO_TYPE="LVCMOS33" *)
TRELLIS_IO #(.DIR("OUTPUT")) led_buf_6 (.B(led_pin[6]), .I(led[6]));
(* BEL="X0/Y29/PIOD" *) (* IO_TYPE="LVCMOS33" *)
TRELLIS_IO #(.DIR("OUTPUT")) led_buf_7 (.B(led_pin[7]), .I(led[7]));
(* BEL="X0/Y62/PIOD" *) (* IO_TYPE="LVCMOS33" *)
TRELLIS_IO #(.DIR("OUTPUT")) gpio0_buf (.B(gpio0_pin), .I(gpio0));
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;
always@(posedge clk) begin
ctr <= btn ? ctr : (dir ? ctr - 1'b1 : ctr + 1'b1);
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;
// Tie GPIO0, keep board from rebooting
assign gpio0 = 1'b1;
endmodule
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