FPGA+verilog 编程之----跑马灯

FPGA

本帖最后由 FPGAbo 于 2012-5-28 12:59 编辑

什么是跑马灯？8个led灯，每一个时刻8个只有一个被点亮，可以认为8个led灯逐个被点亮过，给人直观的感觉是有一个灯在不断的跑来跑去。跑马灯的实现可以认为是对位数据的操作，可以应用到的位操作可以分为左右移位移位、逐个赋值、循环移位等。以下的代码中以8bit的led为例，依旧是1点亮，0熄灭；每一次被点亮的led灯持续的时间为0.1s=100ms，系统时钟是50Mhz,通过不同的语句实现不同的跑马灯。由于博客网站编辑功能太差，可以讲代码部分复制在专有代码编辑器中；便于阅读
`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Engineer: FpgaBo
/// Create Date: 09:42:41 05/25/2012
// Module Name: RunLed
// Project Name: 8位跑马灯
// Target Devices: XS3C500E-5PQ205
// Tool versions: ISE 12.3+Modelsim SE6.6
// Revision 0.01 - File Created
// Additional Comments: 25000000
////////////////////////////////////////////////////////////////////////////////////
module RunLed(
input CLK,
input RSTn,
output [7:0] LedRun1Lift8,//依然是帕斯卡命名法 1代表第一组，8代表led的个数，左移
output [7:0] LedRun2Lift8,
output [7:0] LedRun3Lift8,
output [7:0] LedRun1Left1Right8,//一次左移一次右移，如此循环
output [7:0] LedRun3Right2Left8//3次右移两次左移，
);
  //50Mhz,20ns,20ns*50000=1ms,2^16 =65 536 counter[15:0]
// parameter  T1MS  = 49_999;//实际分频，为什么不是50_000
parameter  T1MS  = 49;//used in TestBench
// parameter  T100MS = 99;
parameter  T100MS = 9;
//////////////////////////////////////////////////////////////////////////////
//计数模块，控制延时信息，每个灯被点亮100ms，先产生一个1ms，再使用一个100的计数器
//////////////////////////////////////////////////////////////////////////////
reg [15:0]counter;
reg [7:0]cnt;
always@(posedge CLK or negedge RSTn)begin
  if(!RSTn)begin
counter <= 16'd0;
  end
  else if(counter  == T1MS )begin
counter <= 16'd0;
  end
  else begin
counter <= counter + 16'd1;
  end
end
always@(posedge CLK or negedge RSTn)begin
  if(!RSTn)begin
cnt <= 8'd0;
  end
  else if(cnt  == T100MS )begin
cnt <= 8'd0;
  end
  else if(counter  == T1MS)begin
cnt <= cnt + 8'd1;
  end
end
//////////////////////////////////////////////////////////////////////////////
//方法一：连接符移位操作
/////////////////////////////////////////////////////////////////////////////
reg [7:0]run1leftr;
always@(posedge CLK or negedge RSTn)begin
if(!RSTn)begin
  run1leftr <= 8'h01;//初始化
end
else if(cnt  == T100MS)begin
  run1leftr <= {run1leftr[6:0],run1leftr[7]};//将最高位的移位到最低位，连接符{}的使用
end
else begin
  run1leftr <= run1leftr;
end
end
assign LedRun1Lift8 = run1leftr;//输出寄存器化
//////////////////////////////////////////////////////////////////////////////
//方法二：移位运算符
//////////////////////////////////////////////////////////////////////////////
reg [7:0]run2leftr;
always@(posedge CLK or negedge RSTn)begin
if(!RSTn)begin
  run2leftr <= 8'h01;
end
else if(cnt  == T100MS)begin
  run2leftr <=  {run2leftr << 1};//移位操作符
if(run2leftr == 8'h80)
run2leftr <= 8'h01;
end
else begin
  run2leftr <=  run2leftr;
end
end
assign LedRun2Lift8 = run2leftr;
//////////////////////////////////////////////////////////////////////////////
//方法三 case 语句跳转
//////////////////////////////////////////////////////////////////////////////
  reg [7:0]run3leftr;
  reg [3:0]i;
always@(posedge CLK or negedge RSTn)begin
if(!RSTn)begin
  run3leftr <= 8'd01;
  i<=4'd0;
end
else begin
  case(i)//case 语句搭建循环
4'd0: begin
   if(cnt  == T100MS) begin
   i<=i+4'd1;
   end
   run3leftr <= 8'h01;
   end
4'd1: begin
   if(cnt  == T100MS) begin  i<=i+4'd1;end run3leftr <= 8'h02;
   end
4'd2: begin
   if(cnt  == T100MS) begin  i<=i+4'd1;end run3leftr <= 8'h04;
   end
4'd3: begin
   if(cnt  == T100MS) begin  i<=i+4'd1;end run3leftr <= 8'h08;
   end
4'd4: begin
   if(cnt  == T100MS) begin  i<=i+4'd1;end run3leftr <= 8'h10;
   end
4'd5: begin
   if(cnt  == T100MS) begin  i<=i+4'd1;end run3leftr <= 8'h20;
   end
4'd6: begin
   if(cnt  == T100MS) begin  i<=i+4'd1;end run3leftr <= 8'h40;
   end
4'd7: begin
   if(cnt  == T100MS) begin  i<=4'd0;end run3leftr <= 8'h80;
   end
default:begin
   run3leftr <= 8'h80;
   i<=4'd0;
   end
  endcase
end
end
assign LedRun3Lift8 = run3leftr;
///////////////////////////////////////////////////////////////////////////////
//左移一次，右移一次
///////////////////////////////////////////////////////////////////////////////
reg [7:0]run1left1rightr;
reg [1:0]j;
always@(posedge CLK or negedge RSTn)begin
if(!RSTn)begin
  run1left1rightr<= 8'h01;
  j <= 2'b01;
end
else if(cnt  == T100MS)begin
  case(j)
2'b01:begin//01--02--04-08-10-20-40-80
   run1left1rightr <= {run1left1rightr[6:0],run1left1rightr[7]};
   if(run1left1rightr==8'h80)begin
   j <= 2'b10;
   run1left1rightr <= 8'h40;
   end
end
2'b10:begin//80-40-20-10-08-04-02-01
   run1left1rightr <= {run1left1rightr[0],run1left1rightr[7:1]};
   if(run1left1rightr==8'h01)begin
   run1left1rightr <= 8'h02;
   j <= 2'b01;
   end
  //  end
end//01-80-10
default:begin
   run1left1rightr <= 8'h01;
   j <= 2'b01;
end
  endcase
end
end
assign LedRun1Left1Right8 = run1left1rightr;
///////////////////////////////////////////////////////////////////////////////
//右移3次,左移2次，
///////////////////////////////////////////////////////////////////////////////
reg [7:0]run3right2leftr;
reg [2:0]k;
always@(posedge CLK or negedge RSTn)begin
if(!RSTn)begin
  run3right2leftr<= 8'h80;
  k <= 3'd0;
end
else if(cnt  == T100MS)begin
  case(j)
3'd0,3'd1:begin//80-40-20-10-08-04-02-01-------------- =>          80-01--80-01--80-01--02-80--01-80-01
   run3right2leftr <= {run3right2leftr[0],run3right2leftr[7:1]};
   if(run3right2leftr==8'h01)begin
   run3right2leftr <= 8'h80;
   k <= k + 3'd1;
   end
end
3'd2:begin//80-40-20-10-08-04-02-01-------------- =>
   run3right2leftr <= {run3right2leftr[0],run3right2leftr[7:1]};
   if(run3right2leftr==8'h01)begin
   run3right2leftr <= 8'h02;
   //run3right2leftr <= 8'h02;
   k <= k + 3'd1;
   end
end
//end//01-80-10
3'd3:begin//02--04-08-10-20-40-80-------------- <=
   run3right2leftr <= {run3right2leftr[6:0],run3right2leftr[7]};
   //if(8'h80 == run3right2leftr)begin
   if(8'b10000000 == run3right2leftr)begin
   k <= k + 3'd1;
   run3right2leftr <= 8'h01;
   end
end
3'd4:begin//01--02--04-08-10-20-40-80-------------- <=
   run3right2leftr <= {run3right2leftr[6:0],run3right2leftr[7]};
   if(8'b10000000 == run3right2leftr)begin
   k <= 3'd0;
   run3right2leftr <= 8'h80;
   end
end
default:begin
   run3right2leftr <= 8'h80;
   k <= 3'd0;
end
  endcase
end
end
assign LedRun3Right2Left8 = run3right2leftr;
endmodule