uart带fifo的verilog

下面是一个基本的带FIFO的UART Verilog代码示例：

module uart_with_fifo(
    input clk,
    input reset,
    input rx,
    output tx,
    input [7:0] data_in,
    output [7:0] data_out,
    input write,
    input read,
    input clk_en
);

parameter BAUD_RATE = 9600; // 波特率
parameter CLK_FREQ = 50000000; // 时钟频率

parameter FIFO_DEPTH = 16; // FIFO深度

reg [7:0] fifo[FIFO_DEPTH-1:0];
reg [3:0] write_ptr = 0;
reg [3:0] read_ptr = 0;
reg [3:0] fifo_count = 0;

reg [3:0] bit_count = 0;
reg [7:0] shift_reg = 0;
reg tx_enable = 1;

assign tx = ~tx_enable;

// baud rate generator
reg [15:0] baud_tick = 0;
reg [15:0] baud_tick_max = CLK_FREQ / BAUD_RATE / 16;

always @(posedge clk) begin
    if (reset) begin
        baud_tick <= 0;
    end else if (baud_tick == baud_tick_max - 1) begin
        baud_tick <= 0;
    end else begin
        baud_tick <= baud_tick + 1;
    end
end

// tx state machine
reg [1:0] tx_state = 0;
parameter TX_IDLE = 0;
parameter TX_START = 1;
parameter TX_DATA = 2;
parameter TX_STOP = 3;

always @(posedge clk) begin
    if (reset) begin
        tx_state <= TX_IDLE;
        bit_count <= 0;
        shift_reg <= 0;
        tx_enable <= 1;
    end else begin
        case (tx_state)
            TX_IDLE:
                if (write && fifo_count > 0 && tx_enable) begin
                    tx_state <= TX_START;
                    shift_reg <= 0;
                    shift_reg[0] <= 0;
                    shift_reg[7:1] <= fifo[read_ptr];
                    read_ptr <= read_ptr + 1;
                    if (read_ptr == FIFO_DEPTH) begin
                        read_ptr <= 0;
                    end
                    fifo_count <= fifo_count - 1;
                    tx_enable <= 0;
                end else begin
                    tx_state <= TX_IDLE;
                end
            TX_START:
                tx_state <= TX_DATA;
                bit_count <= 0;
            TX_DATA:
                if (bit_count < 8) begin
                    shift_reg <= {shift_reg[6:0], data_in[bit_count]};
                    bit_count <= bit_count + 1;
                    tx_state <= TX_DATA;
                end else begin
                    tx_state <= TX_STOP;
                end
            TX_STOP:
                tx_state <= TX_IDLE;
                tx_enable <= 1;
        endcase
    end
end

// rx state machine
reg [2:0] rx_state = 0;
parameter RX_IDLE = 0;
parameter RX_START = 1;
parameter RX_DATA = 2;
parameter RX_STOP = 3;

reg [7:0] rx_data = 0;
reg rx_enable = 0;

always @(posedge clk) begin
    if (reset) begin
        rx_state <= RX_IDLE;
        rx_data <= 0;
    end else begin
        case (rx_state)
            RX_IDLE:
                if (rx == 0) begin
                    rx_state <= RX_START;
                    bit_count <= 0;
                    shift_reg <= 0;
                end else begin
                    rx_state <= RX_IDLE;
                end
            RX_START:
                rx_state <= RX_DATA;
                bit_count <= 0;
            RX_DATA:
                if (bit_count < 8) begin
                    shift_reg <= {shift_reg[6:0], rx};
                    bit_count <= bit_count + 1;
                    rx_state <= RX_DATA;
                end else begin
                    rx_state <= RX_STOP;
                end
            RX_STOP:
                rx_state <= RX_IDLE;
                if (rx == 1) begin
                    rx_data <= shift_reg;
                    rx_enable <= 1;
                end else begin
                    rx_enable <= 0;
                end
        endcase
    end
end

// fifo
always @(posedge clk) begin
    if (reset) begin
        write_ptr <= 0;
        read_ptr <= 0;
        fifo_count <= 0;
    end else begin
        if (clk_en) begin
            if (write && fifo_count < FIFO_DEPTH) begin
                fifo[write_ptr] <= data_in;
                write_ptr <= write_ptr + 1;
                if (write_ptr == FIFO_DEPTH) begin
                    write_ptr <= 0;
                end
                fifo_count <= fifo_count + 1;
            end else if (read && fifo_count > 0) begin
                read_ptr <= read_ptr + 1;
                if (read_ptr == FIFO_DEPTH) begin
                    read_ptr <= 0;
                end
                fifo_count <= fifo_count - 1;
            end
        end
    end
end

// data in/out
assign data_out = rx_data;
assign tx_enable = (tx_state == TX_IDLE) && (fifo_count > 0);

endmodule

此代码实现了一个带有FIFO缓冲区的UART模块，可以通过读/写接口向FIFO缓冲区中写入/读取字节，并通过tx和rx接口进行串口通信。它还包括一个波特率发生器和一个状态机来实现数据的传输和接收。需要注意的是，此代码是一种基本实现，您需要根据您的特定需求进行修改和调整。