Verliog采用SPI协议与单片机沟通

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更新时间:2024-09-21

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FPGA采用SPI协议与单片机沟通

单片机与FPGA沟通方式有很多种，只要规定好协议后，做到通信是完成没问题的。
首先先将FPGA的SPI实现…SPI协议不做追溯了。
闲话不多说，先付代码、

module SPILED(
 input clk,
 input rst_n,
 input SCK,
 input CS_N,
 input MOSI,
 output reg MISO,
 output reg [7:0]rxd_data,
 output rxd_flag,
 output reg led0,
 output reg led1,
 output reg led2,
 output reg led3
 );
 //-----------------capture sck side---------//
 reg sck_r0,sck_r1;
 wire sck_n,sck_p;
 reg [7:0]txd_data;
 initial txd_data[7:0] <= 8'd11;
 always@(posedge clk or negedge rst_n)
 begin
  if(!rst_n)
   begin
    sck_r0 <= 1'b1;   //sck of the idle state is high 
    sck_r1 <= 1'b1;
   end
  else
   begin
    sck_r0 <= SCK;
    sck_r1 <= sck_r0;
   end
 end
 assign sck_n = (~sck_r0 & sck_r1)? 1'b1:1'b0;   //capture the sck negedge
 assign sck_p = (~sck_r1 & sck_r0)? 1'b1:1'b0;   //capture the sck posedge

从机如何读数据

//---------------spi_slaver read data---------//
 reg rxd_flag_r;
 reg [2:0]rxd_state;
 always@(posedge clk or negedge rst_n)
  begin
   if(!rst_n)
    begin
     rxd_data <= 1'b0;
     rxd_flag_r <= 1'b0;
     rxd_state <= 1'b0;
    end
   else if(sck_n&&!CS_N)
    begin
     case(rxd_state)
      3'd0:begin
        rxd_data[7]<=MOSI;
        rxd_flag_r <= 1'b0;
        rxd_state <= 3'd1;
        end
      3'd1:begin
        rxd_data[6]<=MOSI;
        rxd_state <= 3'd2;
        end 
      3'd2:begin
        rxd_data[5]<=MOSI;
        rxd_state <= 3'd3;
        end 
      3'd3:begin
        rxd_data[4]<=MOSI;
        rxd_state <= 3'd4;
        end       
      3'd4:begin
        rxd_data[3]<=MOSI;
        rxd_state <= 3'd5;
        end        
      3'd5:begin
        rxd_data[2]<=MOSI;
        rxd_state <= 3'd6;
        end       
      3'd6:begin
        rxd_data[1]<=MOSI;
        rxd_state <= 3'd7;
        end      
      3'd7:begin
        rxd_data[0]<=MOSI;
        rxd_flag_r <= 1'b1;
        rxd_state <= 3'd0;
        end    
      default: ;
     endcase
    end
  end

中间穿插用灯指示一下。

   always@(posedge clk )
  begin
  led0 <= rxd_data[0];
  led1 <= rxd_data[1];
  led2 <= rxd_data[2];
  led3 <= rxd_data[3];
  end

从机发送数据

//--------------------capture spi_flag posedge--------------------------------
 reg rxd_flag_r0,rxd_flag_r1;
 always@(posedge clk or negedge rst_n)
  begin
   if(!rst_n)
    begin
     rxd_flag_r0 <= 1'b0;
     rxd_flag_r1 <= 1'b0;
    end
   else
    begin
     rxd_flag_r0 <= rxd_flag_r;
     rxd_flag_r1 <= rxd_flag_r0;
   end
 end
assign rxd_flag = (~rxd_flag_r1 & rxd_flag_r0)? 1'b1:1'b0;   //capture rxd_flag_r posedge
//---------------------spi_slaver send data---------------------------
 reg [2:0] txd_state;
 always@(posedge clk or negedge rst_n)
  begin
   if(!rst_n)
    begin
     txd_state <= 1'b0;
    end
   else if(sck_p && !CS_N)
    begin
     case(txd_state)
      3'd0:begin
                       MISO <= txd_data[7];
                       txd_state <= 3'd1;
                       end
      3'd1:begin
                       MISO <= txd_data[6];
                       txd_state <= 3'd2;
         end
      3'd2:begin
                       MISO <= txd_data[5];
                       txd_state <= 3'd3;
                      end
      3'd3:begin
                       MISO <= txd_data[4];
                       txd_state <= 3'd4;
                       end
      3'd4:begin
                       MISO <= txd_data[3];
                       txd_state <= 3'd5;
                      end
      3'd5:begin
                       MISO <= txd_data[2];
                       txd_state <= 3'd6;
                      end
      3'd6:begin
                       MISO <= txd_data[1];
                       txd_state <= 3'd7;
                       end
      3'd7:begin
                       MISO <= txd_data[0];
                       txd_state <= 3'd0;
                       end
                 default: ;
             endcase
         end
 end 
endmodule

以上都是FPGA端的，当时写的单片机的软件SPI，注意时序边沿对应。当然软件SPI通信效率很低，但是谁让单片机硬件SPI总出错呢。
需要软件SPI的，请私信吧，这里不写了。

作者：没脑子的人

spi 沟通单片机

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