1.用System Verilog书写7位数据位，1位偶校验，波特率为115200bps的uart串行发送端 2. 用SV书写对应的行为模型（接收端），并输出激励中的字节值，奇偶性错误的，输出校验错误 3.编写testcase

1. 串行发送端代码：

module uart_tx
(
    input clk,
    input rst,
    input [6:0] data_in,
    output reg tx,
    output reg parity
);

reg [10:0] counter;
reg [7:0] shift_reg;
reg [7:0] data_with_parity;

//计算奇偶校验位
always_comb
begin
    data_with_parity = {data_in, 1'b0};
    parity = ^data_with_parity;
end

always @(posedge clk or posedge rst)
begin
    if (rst) begin
        counter <= 11'b0;
        shift_reg <= 8'h00;
        tx <= 1'b1;
    end
    else begin
        if (counter == 11'b0) begin //发送起始位
            shift_reg <= data_with_parity;
            counter <= counter + 1;
            tx <= 1'b0;
        end
        else if (counter == 11'd9) begin //发送停止位
            shift_reg <= 8'hFF;
            counter <= counter + 1;
        end
        else if (counter == 11'd10) begin //重置状态
            counter <= 11'b0;
            shift_reg <= 8'h00;
            tx <= 1'b1;
        end
        else begin //发送数据位
            shift_reg <= {shift_reg[6:0], data_in[counter - 2]};
            counter <= counter + 1;
        end
    end
end

endmodule

2. 串行接收端代码：

module uart_rx
(
    input clk,
    input rst,
    input rx,
    output reg [6:0] data_out,
    output reg parity_error,
    output reg frame_error,
    output reg overrun_error
);

reg [10:0] counter;
reg [7:0] shift_reg;
reg [6:0] data_reg;
reg last_rx;

//计算奇偶校验位
function automatic bit calc_parity;
    input [7:0] data;
    begin
        calc_parity = ^data;
    end
endfunction

always @(posedge clk or posedge rst)
begin
    if (rst) begin
        counter <= 11'b0;
        shift_reg <= 8'h00;
        data_reg <= 7'b0;
        parity_error <= 1'b0;
        frame_error <= 1'b0;
        overrun_error <= 1'b0;
    end
    else begin
        if (rx != last_rx) begin //检测起始位
            if (rx == 1'b0) begin
                counter <= counter + 1;
                shift_reg <= 8'h00;
                data_reg <= 7'b0;
            end
            else begin
                //起始位错误
                frame_error <= 1'b1;
                counter <= 11'b0;
                shift_reg <= 8'h00;
                data_reg <= 7'b0;
            end
        end
        else if (counter > 0 && counter < 11) begin //接收数据位和校验位
            shift_reg <= {shift_reg[6:0], rx};
            counter <= counter + 1;
            if (counter == 11) begin //接收完成
                data_reg <= shift_reg[6:0];
                shift_reg <= 8'h00;
                counter <= 11'b0;
                if (calc_parity(data_reg) != rx) begin //校验错误
                    parity_error <= 1'b1;
                end
            end
        end
        else if (counter == 11 && rx == 1'b0) begin //接收停止位
            counter <= 11'b0;
            shift_reg <= 8'h00;
            data_out <= data_reg;
        end
        else if (counter == 11 && rx == 1'b1) begin //停止位错误
            frame_error <= 1'b1;
            counter <= 11'b0;
            shift_reg <= 8'h00;
            data_reg <= 7'b0;
        end
        if (counter == 0 && rx == 0 && last_rx == 0) begin //溢出错误
            overrun_error <= 1'b1;
            shift_reg <= 8'h00;
            data_reg <= 7'b0;
        end
        last_rx <= rx;
    end
end

endmodule

3. 测试代码：

module test_uart;

//串行发送端实例
uart_tx tx_inst(
    .clk(clk),
    .rst(rst),
    .data_in(data_in),
    .tx(tx),
    .parity(parity)
);

//串行接收端实例
uart_rx rx_inst(
    .clk(clk),
    .rst(rst),
    .rx(rx),
    .data_out(data_out),
    .parity_error(parity_error),
    .frame_error(frame_error),
    .overrun_error(overrun_error)
);

reg clk;
reg rst;
reg [6:0] data_in;
wire tx;
wire parity;
wire rx;
wire [6:0] data_out;
wire parity_error;
wire frame_error;
wire overrun_error;

//时钟和复位信号
initial begin
    clk = 0;
    forever #5 clk = ~clk;
end

initial begin
    rst = 1;
    #10 rst = 0;
end

//初始测试数据
initial begin
    data_in = 7'b1001001;
    #100;
    data_in = 7'b0101010;
    #100;
end

//测试奇偶校验错误
initial begin
    data_in = 7'b0000111;
    #100;
end

//测试帧错误
initial begin
    data_in = 7'b1001001;
    #100;
    data_in = 7'b0101010;
    #5 rx = 1;
    #5 rx = 0;
    #5 rx = 1;
    #5 rx = 1;
    #5;
end

//测试溢出错误
initial begin
    data_in = 7'b1001001;
    #100;
    data_in = 7'b0101010;
    #5 rx = 0;
    #100 rx = 0;
end

endmodule