数字IC-序列检测-fsm_序列测试中pwdnb

序列检测简介及代码实现

序列检测器包含两种，一种是移位寄存器，另一种时状态机，还有重复序列和不重复序列检测。重点关注和了解如何用状态机去实现。

序列检测器就是将指定的序列从数字码流 中检测出来，收到输出1，否则输出0

移位寄存器解法

重复序列检测1101序列

module seq_detect1(
    input clk ,
    input rst_n ,
    input din ,
    output flg  ,
);
 
reg [3:0] din_t ;
always @(posedge clk or negedge rst_n) begin
    if(!rst_n)
    din_t <= 4'b0 ;
    else 
    din_t <= {din_t[2:0] ,din};
end
assign flg = (din_t==4'b1101) ? 1'b1 :1'b0 ;
endmodule

不重复序列检测1101

module seq_detect2(
    input clk ,
    input rst_n ,
    input din ,
    output flg  ,
);
reg [1:0] cnt;
reg [3:0] din_t ;
 
 
always @(posedge clk or negedge rst_n) begin
    if(!rst_n)
    cnt <= 1'b0;
    else if(cnt==2'd3)
    cnt <= 1'b0;
    else 
    cnt <= cnt+1'b1;
    
end
always @(posedge clk or negedge rst_n) begin
    if(!rst_n)
    din_t <= 4'b0 ;
    else 
    din_t <= {din_t[2:0] ,din};
end
assign flg = (din_t==4'b1101) && (cnt==2'd3)? 1'b1 :1'b0 ;
endmodule

状态机解法

此处采用的状态机是三段式Moore状态机的写法

重复序列检测1101

 

module seq_detect3 (
    input clk ,
    input rst_n,
    input din ,
    output  reg flag ,
);
    reg [4:0] cur_state;
    reg [4:0] next_state ;
 
    localparam IDLE = 5'b00001;
    localparam SEQ1 = 5'b00010;
    localparam SEQ11 = 5'b00100;
    localparam SEQ110 = 5'b01000;
    localparam SEQ1101  = 5'b10000 ;
//状态机三段式
    always@(posedge clk or negedge rst_n)begin
        if(!rst_n)
        cur_state <= IDLE;
        else 
        cur_state <= next_state ;
    end 
    always@(*)
begin
    case(cur_state)
        IDLE : next_state = din ? SEQ1 : IDLE;
        SEQ1 : next_state = din ? SEQ11 : IDLE ;
        SEQ11: next_state = din ? SEQ11 : SEQ110 ;
        SEQ110 : next_state = din ? SEQ1101 : IDLE ;
        SEQ1101 :next_state = din ? SEQ11 : IDLE ;
    default : next_state  = IDLE ;
    endcase
end   
always @(posedge clk or negedge rst_n) begin
    if(!rst_n)
    flag <= 1'b0 ;
    else if(cur_state==SEQ1101)
    flag <= 1'b1;
    else 
    flag <= 1'b0 ;
end
 
 
 
endmodule

 不重复序列检测1101

 

module seq_detect4 (
    input clk ,
    input rst_n,
    input din ,
    output  reg flag ,
);
    reg [4:0] cur_state;
    reg [4:0] next_state ;
 
    localparam IDLE = 5'b00001;
    localparam SEQ1 = 5'b00010;
    localparam SEQ11 = 5'b00100;
    localparam SEQ110 = 5'b01000;
    localparam SEQ1101  = 5'b10000 ;
//状态机三段式
    always@(posedge clk or negedge rst_n)begin
        if(!rst_n)
        cur_state <= IDLE;
        else 
        cur_state <= next_state ;
    end 
    always@(*)
begin
    case(cur_state)
        IDLE : next_state = din ? SEQ1 : IDLE;
        SEQ1 : next_state = din ? SEQ11 : IDLE ;
        SEQ11: next_state = din ? IDLE : SEQ110 ;
        SEQ110 : next_state = din ? SEQ1101 : IDLE ;
        SEQ1101 :next_state = IDLE ;
    default : next_state  = IDLE ;
    endcase
end   
always @(posedge clk or negedge rst_n) begin
    if(!rst_n)
    flag <= 1'b0 ;
    else if(cur_state==SEQ1101)
    flag <= 1'b1;
    else 
    flag <= 1'b0 ;
end
 
 
 
endmodule