基于fpga的单线激光雷达数据处理

激光雷达：

首先来给大家稍微介绍以下激光雷达，激光雷达，即Light Detation and ranging,它相比于其他雷达，优点非常明确，包括 1）、具有极高的分辨率；

2）、抗干扰能力强；

3）、获取的信息量丰富；

4）、全天时工作；

最近一段时间有幸接触到镭神LS01C型单线激光雷达，LS01C型激光雷达是深圳市镭神智能系统公司研发的一款低成本二维扫描测距产品。该激光雷达可实现6米范围内的360°二维平面扫描，产生空间的平面点云地图用于地图绘制、机器人自主定位导航、智能设备壁障等应用。

激光测距采用激光三角测距系统，三角测距原理可参考

http://blog.csdn.net/xiangz_csdn/article/details/53814290

LSLIDAR通讯参数：

波特率：230400bps;

校验位：NONE;

数据位：8bits；

停止位：1bits;

数据格式：十六进制。

首先接触雷达，我从数据通信入手，通过uart串口发送启动指令（0xA5 0x2C 0xE1 0xAA 0xBB 0xCC 0xDD
）和停止指令（0xA5 0x25 0xE1 0xAA 0xBB 0xCC 0xDD
）来控制雷达运行和停止。采用两种方法来控制雷达运行状态：（1）、将启动和停止指令预存在程序中，然后和FPGA板子的开关相结合，通过开关来控制雷达；

（2）、采用串口助手来发送指令控制雷达运行和停止。

接下来贡上两种程序代码：

一、预存指令：

  分为四个模块：分频模块clkdiv.v、发送模块uarttx.v、测试模块（存指令模块）test_tx_r.v、顶层模块top_tx_r.v

module clkdiv(clk, clkout); //分频模块
input clk;  
        
output clkout;  
    
 reg clkout; 
reg [15:0] cnt;
always @(posedge clk) 
  
begin //板子时钟为100MHZ，采用16倍波特率进行采样，计算得分频系数为27
if(cnt == 16'd13)
begin  
clkout <= 1'b1; 
cnt <= cnt + 16'd1; 
end  
else if(cnt == 16'd27) 
begin  
clkout <= 1'b0; 
cnt <= 16'd0; 
end 
else 
begin  
cnt <= cnt + 16'd1; 
end 
end 
endmodule

module uarttx(clk, datain, wrsig, idle, tx);//发送模块
input clk;  
    
  
input [7:0] datain;   //并行输入8位数据
input wrsig;   //输入控制位，上升沿有效
output idle;//输出标志位
output tx;  //串行输出数据
 
reg idle, tx; 
reg send;  
reg wrsigbuf, wrsigrise; 
reg presult;  //发送校验
reg[7:0] cnt;   
 
parameter paritymode = 1'b0; 

always @(posedge clk) //判断wrsig的上升沿
begin  
wrsigbuf <= wrsig;  
wrsigrise <= (~wrsigbuf) & wrsig; 
end  
always @(posedge clk) 
begin  
if (wrsigrise && (~idle)) //wrsig为上升沿且处于空闲状态发送数据
 
begin  
send <= 1'b1; //进行发送
end  
else if(cnt == 8'd152) //8位数据发送完毕

begin  
send <= 1'b0; 
end 
end  
always @(posedge clk) 
begin  
if(send == 1'b1) 
begin  
case(cnt)   
    
8'd0: //发送起始位
begin  
tx <= 1'b0; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd16: //发送第一位
begin  
tx <= datain[0];  
  
presult <= datain[0]^paritymode; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd32: //发送第二位
begin  
tx <= datain[1]; 
presult <= datain[1]^presult; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd48: //发送第三位
begin  
tx <= datain[2];  
presult <= datain[2]^presult; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd64: //发送第四位
begin  
tx <= datain[3]; 
presult <= datain[3]^presult; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd80: //发送第五位
begin  
tx <= datain[4];  

presult <= datain[4]^presult; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd96: //发送第六位
begin  
tx <= datain[5];  

presult <= datain[5]^presult; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd112: //发送第七位
begin  
tx <= datain[6]; 

presult <= datain[6]^presult; 
idle <= 1'b1;  //处于忙状态 
cnt <= cnt + 8'd1; 
end 
8'd128: //发送第八位
begin  
tx <= datain[7]; 
presult <= datain[7]^presult;  

idle <= 1'b1;  //处于忙状态 
cnt <= cnt + 8'd1; 
end 
8'd144: //发送停止位
begin  
tx <= 1'b1;  
idle <= 1'b1;  //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd152: 
begin  
tx <= 1'b1; 
idle <= 1'b0;// 处于空闲状态，可以发数据
cnt <= cnt + 8'd1; 
end 
default: 
begin  
cnt <= cnt + 8'd1; 
end 
endcase 
end 
else 
begin  
tx <= 1'b1; 
cnt <= 8'd0; 
idle <= 1'b0; 
end 
end  
endmodule 

module testuart(clk, dataout,wrsig,rst,key_mov,key_stop); 
input clk,rst; 
input key_mov;//开始开关
input key_stop;//停止开关
output[7:0] dataout; 
output wrsig;  //发送指令标志位
reg [7:0] dataout; 
reg wrsig; 
reg [16:0] cnt; 


always @(posedge clk or negedge rst ) 
begin
  if(!rst)begin
    dataout<= 0;
    cnt <=0;
    end
else 
begin
if(key_mov==1'b1)//运行开关闭合有效
  begin
     if(cnt <= 1779) //一组指令周期数
        begin  //发送开始指令
          case(cnt)
          16'd254: begin
                   dataout <= 8'hA5;wrsig <= 1'b1;  cnt <= cnt + 16'd1;end
          16'd508:  begin
                   dataout <= 8'h2C;wrsig <= 1'b1; cnt <= cnt + 16'd1; end
          16'd762: begin
                   dataout <= 8'hE1;wrsig <= 1'b1; cnt <= cnt + 16'd1; end
          16'd1016: begin
                   dataout <= 8'hAA;wrsig <= 1'b1; cnt <= cnt + 16'd1; end
          16'd1270:  begin
                   dataout <= 8'hBB;wrsig <= 1'b1; cnt <= cnt + 16'd1; end
           16'd1524: begin
                   dataout <= 8'hCC;wrsig <= 1'b1; cnt <= cnt + 16'd1; end
          16'd1778: begin
                   dataout <= 8'hDD;wrsig <= 1'b1;  cnt <= cnt + 16'd1;end
            
           default:begin
                  wrsig <= 1'b0;  
                 cnt <= cnt + 16'd1;end
          endcase
        end
      else 
         begin  
          wrsig <= 1'b0; 
          cnt <= 16'd0;  
         end 
     end
else  if(key_stop==1'b1)//停止开关闭合
    begin 
     if(cnt <= 1779) 
        begin  //发送停止指令
          case(cnt)
            16'd254: begin
                       dataout <= 8'hA5;wrsig <= 1'b1;  cnt <= cnt + 16'd1;end
            16'd508:  begin
                      dataout <= 8'h25;wrsig <= 1'b1; cnt <= cnt + 16'd1; end
            16'd762: begin
                    dataout <= 8'hE1;wrsig <= 1'b1; cnt <= cnt + 16'd1; end
            16'd1016: begin
                    dataout <= 8'hAA;wrsig <= 1'b1; cnt <= cnt + 16'd1; end
            16'd1270:  begin
                     dataout <= 8'hBB;wrsig <= 1'b1; cnt <= cnt + 16'd1; end
            16'd1524: begin
                     dataout <= 8'hCC;wrsig <= 1'b1; cnt <= cnt + 16'd1; end
             16'd1778: begin
                     dataout <= 8'hDD;wrsig <= 1'b1;  cnt <= cnt + 16'd1;end
            
            default:begin
                   wrsig <= 1'b0;  
                  cnt <= cnt + 16'd1;end
          endcase
        end
     else 
        begin  
          wrsig <= 1'b0; 
          cnt <= 16'd0;  
        end 
    end
else
        begin  
          wrsig <= 1'b0; 
          cnt <= 16'd0;  
        end 
end
end
endmodule  

module uarttx(clk, datain, wrsig, idle, tx);//发送模块
input clk;  
    
  
input [7:0] datain;   //并行输入8位数据
input wrsig;   //输入控制位，上升沿有效
output idle;//输出标志位
output tx;  //串行输出数据
 
reg idle, tx; 
reg send;  
reg wrsigbuf, wrsigrise; 
reg presult;  //发送校验
reg[7:0] cnt;   
 
parameter paritymode = 1'b0; 

always @(posedge clk) //判断wrsig的上升沿
begin  
wrsigbuf <= wrsig;  
wrsigrise <= (~wrsigbuf) & wrsig; 
end  
always @(posedge clk) 
begin  
if (wrsigrise && (~idle)) //wrsig为上升沿且处于空闲状态发送数据
 
begin  
send <= 1'b1; //进行发送
end  
else if(cnt == 8'd152) //8位数据发送完毕

begin  
send <= 1'b0; 
end 
end  
always @(posedge clk) 
begin  
if(send == 1'b1) 
begin  
case(cnt)   
    
8'd0: //发送起始位
begin  
tx <= 1'b0; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd16: //发送第一位
begin  
tx <= datain[0];  
  
presult <= datain[0]^paritymode; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd32: //发送第二位
begin  
tx <= datain[1]; 
presult <= datain[1]^presult; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd48: //发送第三位
begin  
tx <= datain[2];  
presult <= datain[2]^presult; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd64: //发送第四位
begin  
tx <= datain[3]; 
presult <= datain[3]^presult; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd80: //发送第五位
begin  
tx <= datain[4];  

presult <= datain[4]^presult; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd96: //发送第六位
begin  
tx <= datain[5];  

presult <= datain[5]^presult; 
idle <= 1'b1;   //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd112: //发送第七位
begin  
tx <= datain[6]; 

presult <= datain[6]^presult; 
idle <= 1'b1;  //处于忙状态 
cnt <= cnt + 8'd1; 
end 
8'd128: //发送第八位
begin  
tx <= datain[7]; 
presult <= datain[7]^presult;  

idle <= 1'b1;  //处于忙状态 
cnt <= cnt + 8'd1; 
end 
8'd144: //发送停止位
begin  
tx <= 1'b1;  
idle <= 1'b1;  //处于忙状态
cnt <= cnt + 8'd1; 
end 
8'd152: 
begin  
tx <= 1'b1; 
idle <= 1'b0;// 处于空闲状态，可以发数据
cnt <= cnt + 8'd1; 
end 
default: 
begin  
cnt <= cnt + 8'd1; 
end 
endcase 
end 
else 
begin  
tx <= 1'b1; 
cnt <= 8'd0; 
idle <= 1'b0; 
end 
end  
endmodule 

二、通过串口助手来发送：

      分频模块和上面的一样，此处不再呈上；

module top(clk,rx,tx,idle);
input clk,rx;
output tx,idle;

wire tx,idle;
wire clkout,rdsig;
wire [7:0] dataout;

 clkdiv clkdiv_inst(
 .clk(clk),
 .clkout(clkout)
  );
 
 uarttx uarttx_inst(
   .clk(clkout), 
   .datain(dataout), 
   .wrsig(rdsig), 
   .idle(idle), 
   .tx(tx)
   );
  
  uartrx uartrx_inst(
  .clk(clkout), 
  .rx(rx), 
  .dataout(dataout), 
  .rdsig(rdsig)
  );
  endmodule

module uartrx(clk, rx, dataout, rdsig);
input clk; //采样时钟
input rx; //UART 数据输入
output dataout; //接收数据输出
output rdsig;
reg[7:0] dataout;
reg rdsig;
reg [7:0] cnt;
reg rxbuf, rxfall, receive;
parameter paritymode = 1'b0;
reg presult, idle;
always @(posedge clk) //检测线路的下降沿
begin
rxbuf <= rx;
rxfall <= rxbuf & (~rx);
end
always @(posedge clk)
begin
if (rxfall && (~idle)) //检测到线路的下降沿并且原先线路为空闲，启动接收数据进程
begin
receive <= 1'b1;
end
else if(cnt == 8'd152) //接收数据完成
begin
receive <= 1'b0;
end
end
always @(posedge clk)
begin
if(receive == 1'b1)
begin
case (cnt)
8'd0:
begin
idle <= 1'b1;
cnt <= cnt + 8'd1;
rdsig <= 1'b0;
end
8'd24: //接收第 0 位数据
begin
idle <= 1'b1;
dataout[0] <= rx;
presult <= paritymode^rx;
cnt <= cnt + 8'd1;
rdsig <= 1'b0;
end
8'd40: //接收第 1 位数据
begin
idle <= 1'b1;
dataout[1] <= rx;
presult <= presult^rx;
cnt <= cnt + 8'd1;
rdsig <= 1'b0;
end
8'd56: //接收第 2 位数据
begin
idle <= 1'b1;
dataout[2] <= rx;
presult <= presult^rx;
cnt <= cnt + 8'd1;
rdsig <= 1'b0;
end
8'd72: //接收第 3 位数据
begin
idle <= 1'b1;
dataout[3] <= rx;
presult <= presult^rx;
cnt <= cnt + 8'd1;
rdsig <= 1'b0;
end
8'd88: //接收第 4 位数据
begin
idle <= 1'b1;
dataout[4] <= rx;
presult <= presult^rx;
cnt <= cnt + 8'd1;
rdsig <= 1'b0;
end
8'd104: //接收第 5 位数据
begin
idle <= 1'b1;
dataout[5] <= rx;
presult <= presult^rx;
cnt <= cnt + 8'd1;
rdsig <= 1'b0;
end
8'd120: //接收第 6 位数据
begin
idle <= 1'b1;
dataout[6] <= rx;
presult <= presult^rx;
cnt <= cnt + 8'd1;
rdsig <= 1'b0;
end
8'd136: //接收第 7 位数据
begin
idle <= 1'b1;
dataout[7] <= rx;
presult <= presult^rx;
cnt <= cnt + 8'd1;
rdsig <= 1'b0;
end
8'd144:
begin
idle <= 1'b1;
cnt <= cnt + 1'b1;
rdsig <= 1'b1;
end
default:
begin
cnt <= cnt + 8'd1;
end
endcase
end
else
begin
cnt <= 8'd0;
idle <= 1'b0;
rdsig <= 1'b0;
end
end
endmodule

module uarttx(clk, datain, wrsig, idle, tx);
input clk; //UART 时钟
input [7:0] datain; //需要发送的数据
input wrsig; //发送命令，上升沿有效
output idle; //线路状态指示，高为线路忙，低为线路空闲
output tx; //发送数据信号
reg idle, tx;
reg send;
reg wrsigbuf, wrsigrise;
reg presult;
reg[7:0] cnt; //计数器
parameter paritymode = 1'b0;
//检测发送命令是否有效
always @(posedge clk)
begin
wrsigbuf <= wrsig;
wrsigrise <= (~wrsigbuf) & wrsig;
end
always @(posedge clk)
begin
if (wrsigrise && (~idle)) //当发送命令有效且线路为空闲时，启动新的数据发送进程
begin
send <= 1'b1;
end
else if(cnt == 8'd152) //一帧资料发送结束
begin
send <= 1'b0;
end
end
always @(posedge clk)
begin
if(send == 1'b1)
begin
case(cnt) //产生起始位
8'd0:
begin
tx <= 1'b0;
idle <= 1'b1;
cnt <= cnt + 8'd1;
end
8'd16:
begin
tx <= datain[0]; //发送数据 0 位
presult <= datain[0]^paritymode;
idle <= 1'b1;
cnt <= cnt + 8'd1;
end
8'd32:
begin
tx <= datain[1]; //发送数据 1 位
presult <= datain[1]^presult;
idle <= 1'b1;
cnt <= cnt + 8'd1;
end
8'd48:
begin
tx <= datain[2]; //发送数据 2 位
presult <= datain[2]^presult;
idle <= 1'b1;
cnt <= cnt + 8'd1;
end
8'd64:
begin
tx <= datain[3]; //发送数据 3 位
presult <= datain[3]^presult;
idle <= 1'b1;
cnt <= cnt + 8'd1;
end
8'd80:
begin
tx <= datain[4]; //发送数据 4 位
presult <= datain[4]^presult;
idle <= 1'b1;
cnt <= cnt + 8'd1;
end
8'd96:
begin
tx <= datain[5]; //发送数据 5 位
presult <= datain[5]^presult;
idle <= 1'b1;
cnt <= cnt + 8'd1;
end
8'd112:
begin
tx <= datain[6]; //发送数据 6 位
presult <= datain[6]^presult;
idle <= 1'b1;
cnt <= cnt + 8'd1;
end
8'd128:
begin
tx <= datain[7]; //发送数据 7 位
presult <= datain[7]^presult;
idle <= 1'b1;
cnt <= cnt + 10'd1;
end
8'd144:
begin
tx <= 1'b1; //发送停止位
idle <= 1'b1;
cnt <= cnt + 8'd1;
end
8'd152:
begin
tx <= 1'b1;
idle <= 1'b0; //一帧资料发送结束
cnt <= cnt + 8'd1;
end
default:
begin
cnt <= cnt + 8'd1;
end
endcase
end
else
begin
tx <= 1'b1;
cnt <= 8'd0;
idle <= 1'b0;
end
end
endmodule

串口通信是熟悉板子的入门练习，可以深刻理解发送数据的方式，以及波特率的含义和计算。