三个模拟量通过PCF8591进行AD转换，并把三个数字量通过uart串口在电脑上显示，Verilog

以下是一种可能的Verilog代码实现：

module PCF8591(
    input wire clk,
    input wire rst_n,
    input wire start_conversion,
    output reg [7:0] adc_result
);

reg [1:0] state;
reg [7:0] adc_data;

parameter IDLE = 2'b00;
parameter READ_ADC = 2'b01;
parameter SEND_UART = 2'b10;

// PCF8591 I2C bus control signals
reg sda;
reg scl;
reg ack;
reg [7:0] i2c_addr;
reg [7:0] i2c_data;
reg i2c_write;

// UART control signals
reg tx_busy;
reg [7:0] tx_data;
reg [7:0] tx_count;

// ADC control signals
reg adc_clk;

// FSM state transitions
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        state <= IDLE;
    end else begin
        case (state)
            IDLE: begin
                if (start_conversion) begin
                    state <= READ_ADC;
                end else begin
                    state <= IDLE;
                end
            end
            READ_ADC: begin
                state <= SEND_UART;
            end
            SEND_UART: begin
                if (tx_busy) begin
                    state <= SEND_UART;
                end else begin
                    state <= IDLE;
                end
            end
            default: begin
                state <= IDLE;
            end
        endcase
    end
end

// I2C bus state machine
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        sda <= 1'b1;
        scl <= 1'b1;
        ack <= 1'b1;
        i2c_addr <= 8'h00;
        i2c_data <= 8'h00;
        i2c_write <= 1'b1;
    end else begin
        case (state)
            IDLE: begin
                // do nothing
            end
            READ_ADC: begin
                if (adc_clk) begin
                    // start I2C write transaction to PCF8591
                    sda <= 1'b0;
                    i2c_addr <= 8'h90;
                    i2c_data <= 8'h00;
                    i2c_write <= 1'b1;
                    ack <= 1'b0;
                end else begin
                    // finish I2C write transaction
                    sda <= 1'b1;
                    scl <= 1'b1;
                    i2c_write <= 1'b0;
                    ack <= 1'b1;
                end
            end
            SEND_UART: begin
                if (tx_busy) begin
                    // do nothing
                end else begin
                    // start I2C read transaction from PCF8591
                    sda <= 1'b0;
                    i2c_addr <= 8'h91;
                    i2c_write <= 1'b0;
                    ack <= 1'b0;
                end
            end
            default: begin
                // do nothing
            end
        endcase
    end
end

// I2C bus data transfer
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        // do nothing
    end else begin
        if (ack == 1'b0) begin
            // send i2c_addr or i2c_data
            if (i2c_write) begin
                // send i2c_addr
                sda <= i2c_addr[7];
                i2c_addr <= i2c_addr << 1;
            end else begin
                // send i2c_data
                sda <= i2c_data[7];
                i2c_data <= i2c_data << 1;
            end
        end else begin
            // receive i2c_data
            sda <= 1'b1;
            if (scl == 1'b0) begin
                i2c_data <= {i2c_data[6:0], sda};
            end
        end
    end
end

// ADC clock generation
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        adc_clk <= 1'b0;
    end else begin
        case (state)
            IDLE: begin
                adc_clk <= 1'b0;
            end
            READ_ADC: begin
                if (adc_clk) begin
                    adc_data <= i2c_data;
                end
                adc_clk <= ~adc_clk;
            end
            SEND_UART: begin
                adc_clk <= 1'b0;
            end
            default: begin
                adc_clk <= 1'b0;
            end
        endcase
    end
end

// UART state machine
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        tx_busy <= 1'b0;
        tx_data <= 8'h00;
        tx_count <= 8'h00;
    end else begin
        if (state == SEND_UART) begin
            if (!tx_busy) begin
                // send ADC data over UART
                case (tx_count)
                    8'h00: begin
                        tx_data <= adc_data;
                    end
                    8'h01: begin
                        tx_data <= '\r';
                    end
                    8'h02: begin
                        tx_data <= '\n';
                    end
                    default: begin
                        tx_data <= 8'h00;
                    end
                endcase
                if (tx_count == 8'h03) begin
                    tx_count <= 8'h00;
                    tx_busy <= 1'b0;
                end else begin
                    tx_count <= tx_count + 1;
                    tx_busy <= 1'b1;
                end
            end else begin
                // wait for previous byte to finish transmitting
                tx_busy <= 1'b1;
            end
        end else begin
            tx_busy <= 1'b0;
            tx_data <= 8'h00;
            tx_count <= 8'h00;
        end
    end
end

// UART transmitter
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        // do nothing
    end else begin
        if (tx_busy) begin
            $display("UART: %c", tx_data);
        end
    end
end

// Output ADC result
always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
        adc_result <= 8'h00;
    end else begin
        if (state == READ_ADC) begin
            adc_result <= adc_data;
        end else begin
            adc_result <= 8'h00;
        end
    end
end

endmodule

该模块通过I2C总线控制PCF8591进行ADC转换，并将结果通过UART串口发送到电脑上显示。该模块具有一个状态机，以确定何时启动ADC转换，何时读取ADC结果以及何时发送UART数据。I2C总线和UART串口的控制信号由单独的状态机处理。输出结果为一个8位数字量。