项目场景：

See also: Serial receiver and datapath

We want to add parity checking to the serial receiver. Parity checking adds one extra bit after each data byte. We will use odd parity, where the number of 1s in the 9 bits received must be odd. For example, 101001011 satisfies odd parity (there are 5 1s), but 001001011 does not.

Change your FSM and datapath to perform odd parity checking. Assert the done signal only if a byte is correctly received and its parity check passes. Like the serial receiver FSM, this FSM needs to identify the start bit, wait for all 9 (data and parity) bits, then verify that the stop bit was correct. If the stop bit does not appear when expected, the FSM must wait until it finds a stop bit before attempting to receive the next byte.

You are provided with the following module that can be used to calculate the parity of the input stream (It’s a TFF with reset). The intended use is that it should be given the input bit stream, and reset at appropriate times so it counts the number of 1 bits in each byte.

module parity (
    input clk,
    input reset,
    input in,
    output reg odd);

    always @(posedge clk)
        if (reset) odd <= 0;
        else if (in) odd <= ~odd;

endmodule

Note that the serial protocol sends the least significant bit first, and the parity bit after the 8 data bits.
Some timing diagrams
No framing errors. Odd parity passes for first byte, fails for second byte.

问题描述

请参见:串行接收器和数据路径。
我们想在串行接收器中添加奇偶校验。奇偶校验在每个数据字节后增加一个额外的位。我们将使用奇数奇偶校验，其中接收的9位中的1的数量必须为奇数。例如，101001011满足奇偶校验(有5个1)，而001001011不满足奇偶校验。
修改FSM和数据路径为奇偶校验。只有当一个字节被正确接收并且其奇偶校验通过时，才断言完成的信号。像串行接收FSM一样，这个FSM需要识别起始位，等待所有9位(数据和校验位)，然后验证停止位是否正确。如果停止位没有出现，FSM必须等待，直到它找到一个停止位，然后再尝试接收下一个字节。
您可以使用以下模块来计算输入流的奇偶校验(它是一个带复位的TFF)。预期的用途是，应该给它输入位流，并在适当的时间重置，以便它计算每个字节中1位的数量。

module parity (
    input clk,
    input reset,
    input in,
    output reg odd);

    always @(posedge clk)
        if (reset) odd <= 0;
        else if (in) odd <= ~odd;

endmodule

注意，串行协议先发送最低有效位，然后发送校验位。
一些时间图
没有框架的错误。奇偶校验对第一个字节通过，对第二个字节失败。

原因分析：

像串行接收FSM一样，这个FSM需要识别起始位，等待所有9位(数据和校验位)，然后验证停止位是否正确。如果停止位没有出现，FSM必须等待，直到它找到一个停止位，然后再尝试接收下一个字节。
首先要寻找起始位0，找到起始位后依次识别8位数据位和1位奇偶校验位，再次就是寻找停止位1。通过FSM有限状态机明确状态跳转的条件，通过对状态的判断可以得出done信号的状态转换条件，通过移位寄存器可以对识别到的八位数据进行存储，再结合奇偶校验函数odd可以判断识别到的八位数据是不是我们需要的数据。

解决方案：

module top_module(
    input clk,
    input in,
    input reset,    // Synchronous reset
    output [7:0] out_byte,
    output done
); //
	reg	[3:0] state;
    reg [3:0] next_state;
    parameter	IDEL = 4'd0;
    parameter	START = 4'd1;
    parameter	B1 = 4'd2;
    parameter	B2 = 4'd3;
    parameter	B3 = 4'd4;
    parameter	B4 = 4'd5;
    parameter	B5 = 4'd6;
    parameter	B6 = 4'd7;
    parameter	B7 = 4'd8;
    parameter	B8 = 4'd9;
    parameter	STOP = 4'd10;
    parameter	SEARCH = 4'd11;
    parameter	PARITY = 4'd12;
    reg	[7:0]	data_reg;
    
    always@(*)
        case(state)
            IDEL	:next_state <= (!in) ? START : IDEL;
            START	:next_state <= B1;
            B1		:next_state <= B2;
            B2		:next_state <= B3;
            B3		:next_state <= B4;
            B4		:next_state <= B5;
            B5		:next_state <= B6;
            B6		:next_state <= B7;
            B7		:next_state <= B8;
            B8		:next_state <= PARITY;
            PARITY	:next_state <= (in) ? STOP : SEARCH;
            SEARCH	:next_state <= (in) ? IDEL : SEARCH;
            STOP	:next_state <= (!in) ? START : IDEL ;
            default:next_state <= IDEL;
        endcase
    
    always@(posedge clk)
        if(reset)
            state <= IDEL;
    	else
            state <= next_state;
    
    
     always@(posedge clk) 
        if(reset) 
           data_reg <= 8'd0;
        else
            case(next_state)
                B1: data_reg[0] <= in;
                B2: data_reg[1] <= in;
                B3: data_reg[2] <= in;
                B4: data_reg[3] <= in;
                B5: data_reg[4] <= in;
                B6: data_reg[5] <= in;
                B7: data_reg[6] <= in;
                B8: data_reg[7] <= in;
                PARITY: data_reg <= data_reg;
                STOP: data_reg <= data_reg;
                default: data_reg <= 8'd0;
            endcase     
    //assign done = (odd == 1'b1);
    always@(posedge clk)
        if(reset)
            done <= 1'b0;
    	else	if((next_state == STOP) && (odd == 1'b1))
        	done <= 1'b1;
    	else
            done <= 1'b0;
    // Modify FSM and datapath from Fsm_serialdata
 	always@(posedge clk)
        if(reset)
            out_byte <= 8'd0;
    	else	if((next_state == STOP) && (odd == 1'b1))
            out_byte <= data_reg;
    	else
            out_byte <= 8'd0;
    // New: Add parity checking.
    wire	odd,reset_p;
    assign	reset_p = (next_state == START || reset == 1'b1);
    parity	parity_inst
    (
        . clk	(clk	),
        . reset	(reset_p	),
        . in	(in),
        . odd	(odd	)
    );
	
endmodule

最后

以上就是高大巨人为你收集整理的Serial receiver with parity checking(Fsm serialdp)项目场景：问题描述原因分析：解决方案：的全部内容，希望文章能够帮你解决Serial receiver with parity checking(Fsm serialdp)项目场景：问题描述原因分析：解决方案：所遇到的程序开发问题。

如果觉得靠谱客网站的内容还不错，欢迎将靠谱客网站推荐给程序员好友。