pwm.v

一个在xilinx的ise环境下编译仿真成功的pWM程序。

module pwm(clock,keyin,pwm_out);
    input clock;
    input [1:0] keyin;
    output pwm_out;

	 reg [20:0] count;
	 reg [9:0] pwm_count;
	 reg pwm_reg;
	
always @(posedge clock)
begin
	count=count+1;
	if (count[15:6] < pwm_count)
		pwm_reg=1;
	else
		pwm_reg=0;
end

always @(posedge count[15])
begin
	if (keyin[0] == 1'b0)
	begin
			pwm_count=pwm_count+1;
	end
	else if (keyin[1] == 1'b0)
	begin
			pwm_count=pwm_count-1;
	end
end

assign pwm_out=pwm_reg;

endmodule