基于FPGA的uart程序设计 - - Powered by Discuz!

module uart_rx(
clk,
rst_n,
bps_start,
clk_bps,
rs232_rx,
rx_data,
rx_int,
led
);
input clk; //时钟
input rst_n; //复位
input rs232_rx; //接收数据信号
input clk_bps; //高电平时为接收信号中间采样点
output bps_start; //接收信号时,波特率时钟信号置位
output [7:0] rx_data;//接收数据寄存器
output rx_int; //接收数据中断信号,接收过程中为高
output [7:0] led;
reg [7:0] led;
reg rs232_rx0,rs232_rx1,rs232_rx2,rs232_rx3;//接收数据寄存器
wire neg_rs232_rx;//表示数据线接收到下沿
always @(posedge clk or negedge rst_n) begin
if(!rst_n) begin
rs232_rx0 <= 1'b0;
rs232_rx1 <= 1'b0;
rs232_rx2 <= 1'b0;
rs232_rx3 <= 1'b0;
end
else begin
rs232_rx0 <= rs232_rx;
rs232_rx1 <= rs232_rx0;
rs232_rx2 <= rs232_rx1;
rs232_rx3 <= rs232_rx2;
end
end
assign neg_rs232_rx = rs232_rx3 & rs232_rx2 & ~rs232_rx1 & ~rs232_rx0;//串口传输线的下沿标志
reg bps_start_r;
reg [3:0] num;//移位次数
reg rx_int; //接收中断信号
always @(posedge clk or negedge rst_n)
if(!rst_n) begin
bps_start_r <=1'bz;
rx_int <= 1'b0;
end
else if(neg_rs232_rx) begin//
bps_start_r <= 1'b1; //启动串口,准备接收数据
rx_int <= 1'b1; //接收数据中断使能
end
else if(num==4'd12) begin //接收完有用的信号,
bps_start_r <=1'b0; //接收完毕,改变波特率置位,方便下次接收
rx_int <= 1'b0; //接收信号关闭
end
assign bps_start = bps_start_r;
reg [7:0] rx_data_r;//串口数据寄存器
reg [7:0] rx_temp_data;//当前数据寄存器
always @(posedge clk or negedge rst_n)
if(!rst_n) begin
rx_temp_data <= 8'd0;
num <= 4'd0;
rx_data_r <= 8'd0;
end
else if(rx_int) begin //接收数据处理
if(clk_bps) begin
num <= num+1'b1;
case(num)
4'd1: rx_temp_data[0] <= rs232_rx;
4'd2: rx_temp_data[1] <= rs232_rx;
4'd3: rx_temp_data[2] <= rs232_rx;
4'd4: rx_temp_data[3] <= rs232_rx;
4'd5: rx_temp_data[4] <= rs232_rx;
4'd6: rx_temp_data[5] <= rs232_rx;
4'd7: rx_temp_data[6] <= rs232_rx;
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