VERILONG串口单秒发数据简单实例 -

标题: VERILONG串口单秒发数据简单实例 [打印本页]

作者: nmgbtzyf 时间: 2024-12-24 10:37
标题: VERILONG串口单秒发数据简单实例
/*+++++++TOP++++++++++++*/

module uart_tx(
input             wire          sclk,
      input             wire                rst_n,
      output             reg       uart_tx
);

parameter                CLK_FREQ          =24000000;       //时钟频率50M
parameter                UART_BAUD          = 115200;       //时钟频率50M
parameter                MAX_BIT_COUNT       = 31;       //时钟频率50M
localparam                MAX_BAUD_CNT       = CLK_FREQ / UART_BAUD;//434

reg [7:0] write_data; //发送数据

//运行计数器
reg [31:0] run_cnt;       //波特率计数器
always @(posedge sclk or negedge rst_n)
begin
if(rst_n == 1'b0)
      run_cnt <= 32'd0;
else if(run_cnt == CLK_FREQ)
      run_cnt <= 0;
else
      run_cnt <= run_cnt + 1;
end

//波特率计数器
reg [8:0] baud_cnt;       //波特率计数器
reg en_baud_cnt;       //波特率计数器开关
always @(posedge sclk or negedge rst_n)
begin
if(rst_n == 1'b0)
      baud_cnt <= 8'd0;
else if(en_baud_cnt == 1'b1) begin
      if(baud_cnt == MAX_BAUD_CNT)
         baud_cnt <= 8'd0;
      else
         baud_cnt <= baud_cnt + 1;
end
else
      baud_cnt <= baud_cnt;
end

//发送位计数器
reg [4:0] bit_cnt = 0;       //波特率计数器
always @(posedge sclk or negedge rst_n)
begin
if(rst_n == 1'b0)
      bit_cnt <= 4'd0;
else if(baud_cnt == MAX_BAUD_CNT)
      begin
         if(bit_cnt ==  MAX_BIT_COUNT)
            bit_cnt <= 4'd0;
         else
            bit_cnt <= bit_cnt + 1;
      end
else
      bit_cnt <= bit_cnt;
end

//位发送逻辑
always @(posedge sclk or negedge rst_n)
begin
if(rst_n == 1'b0)
      uart_tx <= 1'b0;
else if(baud_cnt == MAX_BAUD_CNT/2)
      begin
         if(bit_cnt ==  0)
            uart_tx <= 1'b0;
         else if(bit_cnt == MAX_BIT_COUNT)
            uart_tx <= 1'b1;
         else
         begin
         case(bit_cnt)
            1:uart_tx <= write_data[0];
            2:uart_tx <= write_data[1];
            3:uart_tx <= write_data[2];
            4:uart_tx <= write_data[3];
            5:uart_tx <= write_data[4];
            6:uart_tx <= write_data[5];
            7:uart_tx <= write_data[6];
            8:uart_tx <= write_data[7];
            default:uart_tx <= uart_tx;
         endcase
         end
         //uart_tx <= write_data[bit_cnt-1];
      end
else
      uart_tx <= uart_tx;
end

always @(posedge sclk or negedge rst_n)
begin
if(rst_n == 1'b0)
      en_baud_cnt <= 1'b0;
else if(run_cnt == 0) begin
      en_baud_cnt <= 1'b1;
end
else if(bit_cnt ==  MAX_BIT_COUNT && baud_cnt == MAX_BAUD_CNT)
      en_baud_cnt <= 1'b0;
else
      en_baud_cnt <= en_baud_cnt;
end

always @(posedge sclk or negedge rst_n)
begin
if(rst_n == 1'b0)
      write_data <= 8'd0;
else if(run_cnt == 0)
      write_data <= write_data + 1;
else
      write_data <= write_data;
end

endmodule

画红线的一个小问题，有没有人帮我解释一下？
寄存器是八位的最大数值255

但是
MAX_BAUD_CNT数值是434这个应该怎么理解？

IMG_20241224_212921.jpg (324.31 KB, 下载次数: 0)

作者: tyrl800 时间: 2024-12-25 17:00
reg [8:0] baud_cnt;是9位

作者: nmgbtzyf 时间: 2024-12-26 18:32
对对对我，low 真是一起语醒梦中人谢谢

欢迎光临 (http://www.51hei.com/bbs/)