
//时钟极性高，采样沿上升沿
module SPI_Master(
  clk,        // 系统时钟
  rst,        // 复位，低有效
  txd_flag,   // 高电平表示发送完成处于忙碌状态，低电平表示处于空闲状态
  sck,        // 时钟输出
  cs,         // 片选输出
  mosi,       // 主设备输出信号
  miso,       // 主设备输入信号
  txd_signal, // 发送触发信号，给一个信号发送8bit
  rxd_out,    // 接收的数据
  txd_in,     // 发送的数据
  led0,
  led1,
  led2
);
//调试引脚
output led0,led1,led2;
assign led0=txd_signal;
assign led1=txd_flag;
assign led2=cs;
// 输入信号
input clk, rst, miso, txd_signal;
// 输出信号
output reg mosi, txd_flag;
output wire sck, cs;
output reg [7:0] rxd_out;
input [7:0] txd_in;
 
// 内部寄存器和变量
reg [2:0] txd_start;
reg [2:0] txd_start_outside;
reg [3:0] cnt;
reg [3:0] cnt1;
reg csr;
assign sck = cnt1[3];
assign cs = csr;
 
// 任务：根据计数器 cnt1 的值更新时钟状态
task clk_states;
  if (cnt1 == 4'b0000) begin
    cnt1 <= 4'b1111;
    cnt <= cnt + 1'b1;
  end else
    cnt1 <= cnt1 - 1'b1;
endtask
 
// always 块：根据时钟和复位信号控制发送过程和计数器的更新
always @(posedge clk or negedge rst) begin
  if (!rst) begin
    // 复位所有状态和寄存器
    txd_flag <= 1'b0;
    txd_start <= 3'd1;
    cnt <= 4'd0;
    cnt1 <= 4'b1111;
    csr <= 1'b1;
  end else begin
    if (txd_start == txd_start_outside) begin
      csr <= 1'b0;
      txd_flag <= 1'b1; // txd_flag 信号与 cs 信号相反，电路当处于通信时为高电平，表示忙碌状态
      case (cnt) // 为低电平表示空闲状态
        0: clk_states();//进八次cnt加1，SCK经过一个周期，SCK高电平持续时间为4和CLK
        1: clk_states();
        2: clk_states();
        3: clk_states();
        4: clk_states();
        5: clk_states();
        6: clk_states();
        7: begin
          if (cnt1 == 4'b0000) begin
            cnt1 <= 4'b1111;
            cnt <= 4'd8;
          end else
            cnt1 <= cnt1 - 1'b1;
        end
        8: begin
          // 多加一个状态延长 cs 的低电平时间，给从机足够的时间接收数据
          txd_start <= txd_start + 1'b1;
          cnt <= 4'd0;
        end
      endcase
    end else begin
      csr <= 1'b1;
      txd_flag <= 1'b0;
    end
  end
end
 
// always 块：外部触发发送脉冲，上升沿触发发送一次
always @(posedge txd_signal or negedge rst) begin
  if (!rst)
    txd_start_outside <= 1'b0;
  else begin
    if (!txd_flag)
      txd_start_outside <= txd_start_outside + 1'b1;
    else;
  end
end
 
// always 块：sck 上升沿采样数据
reg [7:0] rxd_outr;
reg [2:0] rec_cnt;
always @(posedge sck or negedge rst) begin
  if (!rst) begin
    rxd_out <= 8'h00;
    rec_cnt <= 3'd0;
  end else begin
    case (rec_cnt)
      0: begin
        rxd_outr[7] <= miso;
        rec_cnt <= 3'd1;
      end
      1: begin
        rxd_outr[6] <= miso;
        rec_cnt <= 3'd2;
      end
      2: begin
        rxd_outr[5] <= miso;
        rec_cnt <= 3'd3;
      end
      3: begin
        rxd_outr[4] <= miso;
        rec_cnt <= 3'd4;
      end
      4: begin
        rxd_outr[3] <= miso;
        rec_cnt <= 3'd5;
      end
      5: begin
        rxd_outr[2] <= miso;
        rec_cnt <= 3'd6;
      end
      6: begin
        rxd_outr[1] <= miso;
        rec_cnt <= 3'd7;
      end
      7: begin
        rxd_outr[0] <= miso;
        rxd_out <= {rxd_outr[7:1], miso};
        rec_cnt <= 3'd0;
      end
      default:;
    endcase
  end
end
 
// always 块：sck 下降沿时发送数据
reg [2:0] send_cnt;
always @(negedge sck or negedge rst) begin
  if (!rst)
    send_cnt <= 3'd0;
  else begin
    case (send_cnt)
      0: begin
        mosi <= txd_in[7];
        send_cnt <= 3'd1;
      end
      1: begin
        mosi <= txd_in[6];
        send_cnt <= 3'd2;
      end
      2: begin
        mosi <= txd_in[5];
        send_cnt <= 3'd3;
      end
      3: begin
        mosi <= txd_in[4];
        send_cnt <= 3'd4;
      end
      4: begin
        mosi <= txd_in[3];
        send_cnt <= 3'd5;
      end
      5: begin
        mosi <= txd_in[2];
        send_cnt <= 3'd6;
      end
      6: begin
        mosi <= txd_in[1];
        send_cnt <= 3'd7;
      end
      7: begin
        mosi <= txd_in[0];
        send_cnt <= 3'd0;
      end
      default:;
    endcase
  end
end
 
endmodule

STM32从机

SPI模式配置

SPI参数设置

SPI的DMA传输配置

STM32从机SPI接收代码


int main(void)
{
  /* USER CODE BEGIN 1 */
 
  /* USER CODE END 1 */
 
  /* MCU Configuration--------------------------------------------------------*/
 
  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();
 
  /* USER CODE BEGIN Init */
 
  /* USER CODE END Init */
 
  /* Configure the system clock */
  SystemClock_Config();
 
  /* USER CODE BEGIN SysInit */
 
  /* USER CODE END SysInit */
 
  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_DMA_Init();
  MX_SPI1_Init();
  MX_USART1_UART_Init();
  /* USER CODE BEGIN 2 */
	uint8_t data=0;
	HAL_SPI_Receive_DMA(&hspi1,&data,1);
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
		//FPGA RESET
		HAL_GPIO_WritePin(RST_GPIO_Port,RST_Pin,GPIO_PIN_RESET);
		HAL_Delay(10);
		HAL_GPIO_WritePin(RST_GPIO_Port,RST_Pin,GPIO_PIN_SET);
		//等待发送空闲
		while(HAL_GPIO_ReadPin(txd_flag_GPIO_Port,txd_flag_Pin)==GPIO_PIN_SET){
		};
		//延迟便于观察串口输出
		HAL_Delay(2000);
		//上升沿触发FPGA主机发送
		HAL_GPIO_WritePin(txd_signal_GPIO_Port,txd_signal_Pin,GPIO_PIN_SET);
		HAL_Delay(100);
		HAL_GPIO_WritePin(txd_signal_GPIO_Port,txd_signal_Pin,GPIO_PIN_RESET);
		//串口打印data查看数据
		printf("data is %d \r\n",data);
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

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