无论是课程设计，还是实验课，最好的方法就是在FPGA实验板上进行测试实验，这样可以看到实际交通灯的效果。对每一部分修改可以看到修改的效果，知道程序的修改带来的效果，那样比只看代码要理解的更深刻。
在设计中最好是分模块设计，状态控制，脉冲发生等部分，对每个模块的调试书写时要特别注意每位的意义，尤其在软件绑定引脚时，每个输入输出信号的绑定，引脚的输入输出特性等，要与实际代码中的相符，在调试中不断发现问题，解决问题。
下面附上代码部分：
自制交通灯控制器加倒计时功能：
module traffic(CLK,EN,LIGHT_A,LIGHT_B,TIME_A,TIME_B,a,b,c,d,e,f,g);
output[7:0] TIME_A,TIME_B;
output[2:0] LIGHT_A,LIGHT_B;
output[3:0] a,b,c,d,e,f,g;
input CLK,EN;
reg[7:0] numa,numb;
reg tempa,tempb;
reg[1:0] counta,countb;
reg[5:0] ared,ayellow,agreen,bred,byellow,bgreen;
reg[2:0] LIGHT_A,LIGHT_B;
reg[3:0] a,b,c,d,e,f,g;
always @(EN)
if(!EN)
begin
ared <=8'd45;
ayellow <=8'd05;
agreen <=8'd40;
bred <=8'd45;
byellow <=8'd05;
bgreen <=8'd40;
end
assign TIME_A=numa;
assign TIME_B=numb;
always @(posedge CLK)
begin
if(EN)
begin
if(!tempa)
begin
tempa<=1;
case(counta)
0: begin numa<=ared; LIGHT_A<=4; counta<=1; end
1: begin numa<=agreen; LIGHT_A<=1; counta<=2; end
2:begin numa<=ayellow; LIGHT_A<=2;counta<=0; end
default: LIGHT_A<=4;
endcase
end
else
begin
if(numa>=1)
if(numa[3:0]==0)
begin
numa[3:0]<=9;
numa[7:4]<=numa[7:4]-1;
end
else numa[3:0]<=numa[3:0]-1;
if (numa==0) tempa<=0;
end
end
else
begin
LIGHT_A<=4;
counta<=0;
tempa<=0;
end
end
always @(posedge CLK)
begin
if (EN)
begin
if(!tempb)
begin
tempb<=1;
case (countb)
0: begin numb<=bgreen; LIGHT_B<=1; countb<=1; end
1:begin numb<=byellow; LIGHT_B<=2; countb<=2; end
2: begin numb<=bred; LIGHT_B<=4; countb<=0; end
default: LIGHT_B<=1;
endcase
end
else
begin
if(numb>=1)
if(!numb[3:0])
begin
numb[3:0]<=9;
numb[7:4]<=numb[7:4]-1;
end
else numb[3:0]<=numb[3:0]-1;
if(numb==0) tempb<=0;
end
end
else
begin
LIGHT_B<=4;
tempb<=0;
countb<=0;
end
end
always @(TIME_A)
begin
case(TIME_A[7:4])
4'd0:{a[3],b[3],c[3],d[3],e[3],f[3],g[3]}=7'b1111110;
4'd1:{a[3],b[3],c[3],d[3],e[3],f[3],g[3]}=7'b0110000;
4'd2:{a[3],b[3],c[3],d[3],e[3],f[3],g[3]}=7'b1101101;
4'd3:{a[3],b[3],c[3],d[3],e[3],f[3],g[3]}=7'b1111001;
4'd4:{a[3],b[3],c[3],d[3],e[3],f[3],g[3]}=7'b0110011;
4'd5:{a[3],b[3],c[3],d[3],e[3],f[3],g[3]}=7'b1011011;
4'd6:{a[3],b[3],c[3],d[3],e[3],f[3],g[3]}=7'b1011111;
4'd7:{a[3],b[3],c[3],d[3],e[3],f[3],g[3]}=7'b1110000;
4'd8:{a[3],b[3],c[3],d[3],e[3],f[3],g[3]}=7'b1111111;
4'd9:{a[3],b[3],c[3],d[3],e[3],f[3],g[3]}=7'b1111011;
default:{a[3],b[3],c[3],d[3],e[3],f[3],g[3]}=7'bx;
endcase
end
always @(TIME_A)
begin
case(TIME_A[3:0])
4'd0:{a[2],b[2],c[2],d[2],e[2],f[2],g[2]}=7'b1111110;
4'd1:{a[2],b[2],c[2],d[2],e[2],f[2],g[2]}=7'b0110000;
4'd2:{a[2],b[2],c[2],d[2],e[2],f[2],g[2]}=7'b1101101;
4'd3:{a[2],b[2],c[2],d[2],e[2],f[2],g[2]}=7'b1111001;
4'd4:{a[2],b[2],c[2],d[2],e[2],f[2],g[2]}=7'b0110011;
4'd5:{a[2],b[2],c[2],d[2],e[2],f[2],g[2]}=7'b1011011;
4'd6:{a[2],b[2],c[2],d[2],e[2],f[2],g[2]}=7'b1011111;
4'd7:{a[2],b[2],c[2],d[2],e[2],f[2],g[2]}=7'b1110000;
4'd8:{a[2],b[2],c[2],d[2],e[2],f[2],g[2]}=7'b1111111;
4'd9:{a[2],b[2],c[2],d[2],e[2],f[2],g[2]}=7'b1111011;
default:{a[2],b[2],c[2],d[2],e[2],f[2],g[2]}=7'bx;
endcase
end
always @(TIME_B)
begin
case(TIME_B[7:4])
4'd0:{a[1],b[1],c[1],d[1],e[1],f[1],g[1]}=7'b1111110;
4'd1:{a[1],b[1],c[1],d[1],e[1],f[1],g[1]}=7'b0110000;
4'd2:{a[1],b[1],c[1],d[1],e[1],f[1],g[1]}=7'b1101101;
4'd3:{a[1],b[1],c[1],d[1],e[1],f[1],g[1]}=7'b1111001;
4'd4:{a[1],b[1],c[1],d[1],e[1],f[1],g[1]}=7'b0110011;
4'd5:{a[1],b[1],c[1],d[1],e[1],f[1],g[1]}=7'b1011011;
4'd6:{a[1],b[1],c[1],d[1],e[1],f[1],g[1]}=7'b1011111;
4'd7:{a[1],b[1],c[1],d[1],e[1],f[1],g[1]}=7'b1110000;
4'd8:{a[1],b[1],c[1],d[1],e[1],f[1],g[1]}=7'b1111111;
4'd9:{a[1],b[1],c[1],d[1],e[1],f[1],g[1]}=7'b1111011;
default:{a[1],b[1],c[1],d[1],e[1],f[1],g[1]}=7'bx;
endcase
end
always @(TIME_B)
begin
case(TIME_B[3:0])
4'd0:{a[0],b[0],c[0],d[0],e[0],f[0],g[0]}=7'b1111110;
4'd1:{a[0],b[0],c[0],d[0],e[0],f[0],g[0]}=7'b0110000;
4'd2:{a[0],b[0],c[0],d[0],e[0],f[0],g[0]}=7'b1101101;
4'd3:{a[0],b[0],c[0],d[0],e[0],f[0],g[0]}=7'b1111001;
4'd4:{a[0],b[0],c[0],d[0],e[0],f[0],g[0]}=7'b0110011;
4'd5:{a[0],b[0],c[0],d[0],e[0],f[0],g[0]}=7'b1011011;
4'd6:{a[0],b[0],c[0],d[0],e[0],f[0],g[0]}=7'b1011111;
4'd7:{a[0],b[0],c[0],d[0],e[0],f[0],g[0]}=7'b1110000;
4'd8:{a[0],b[0],c[0],d[0],e[0],f[0],g[0]}=7'b1111111;
4'd9:{a[0],b[0],c[0],d[0],e[0],f[0],g[0]}=7'b1111011;
default:{a[0],b[0],c[0],d[0],e[0],f[0],g[0]}=7'bx;
endcase
end
endmodule
