为什么仿真后计数器只在零和一之间跳变

Question

module breath_led(input clk,
input res,
output reg led,
output reg counter1,
output reg counter10);
reg flag=1'b0;
reg c2=5'd1;

always@(posedge clk)
begin
if(!res)
counter1<=0;
else
counter1<=counter1+1;
end

always@(posedge clk)
begin
if(!res)
counter10<=0;
else
counter10<=counter10+1;
end

always@(posedge clk)
begin
if(counter1==4'd9)
counter10<=0;

if(counter10==4'd9&&flag==1'b0)
begin
counter10<=0;
c2<=c2+1;
end
if(counter10==4'd9&&flag==1'b1)
begin
counter10<=0;
c2<=c2-1;
end
if(c2==5'd11||c2==1'd0)
flag<=~flag;
end

always@(posedge clk)
begin
if(counter1<c2)
led<=1'b1;
else
led<=1'b0;
end
endmodule

我想写一个呼吸灯，让灯在每个大周期（10个时钟内）亮起的时间递增，但是这个计数器实在搞不懂。

Answer 1

你定义的计时器的位宽只有1位，计时器只能在0-1之间变化
你需要这样，将计时器定义成多位
output reg [3:0] counter1;
另外，counter10 你在多个 always 中 赋值，这是不允许的