3.2.5.9 Design a Moore FSM

问题描述

分析：

1.s=000时，打开fr1,fr2,fr3和补充水dfr
2.s=001时，打开fr1,fr2
3.s=011时，打开fr1
4.s=111时，关闭
5.当水位下降时，打开dfr

绘制一下状态转移图

代码：

module top_module (
    input clk,
    input reset,
    input [3:1] s,
    output fr3,
    output fr2,
    output fr1,
    output dfr
); 
	parameter A=0,B=1,C=2,D=3,E=4,F=5;
    reg [2:0] state,next_state;
    always @(posedge clk) begin
        if(reset) state <= A;
        else state <= next_state;
    end
    
    
    always @(*) begin
        case(state)
            A:next_state = s[1]?B:A;
            B:next_state = s[2]?D:(s[1]?B:A);
            C:next_state = s[2]?D:(s[1]?C:A);
            D:next_state = s[3]?F:(s[2]?D:C);
            E:next_state = s[3]?F:(s[2]?E:C);
            F:next_state = s[3]?F:E;
        endcase
    end
    always @(*) begin
        case(state)
            A:{fr3,fr2,fr1,dfr} = 4'b1111; 
            B:{fr3,fr2,fr1,dfr} = 4'b0110;
            C:{fr3,fr2,fr1,dfr} = 4'b0111;
            D:{fr3,fr2,fr1,dfr} = 4'b0010;
            E:{fr3,fr2,fr1,dfr} = 4'b0011;
            F:{fr3,fr2,fr1,dfr} = 4'b0000;
        endcase
    end
endmodule