使用Quartus+modelsim完成本次设计
目录1. "111"检测器
分析
分析题目，得到其有限状态机为下图：
代码实现
module detector111(
input X,
input rst,
input clk,
output OUT
);
reg [1:0]state;
reg [1:0]next_state;
parameter S0=2'd0,S1=2'd1,S2=2'd2,S3=2'd3;
assign OUT = (state==S3)?1:0; //define OUT=1 when S3 state
always @ (posedge clk or posedge rst)
if (rst)
state <= S0;
else
state <= next_state;
always@(*)
case(state)
S0:if(X) next_state <= S1;
else next_state <= S0;
S1:if(X) next_state <= S2;
else next_state <= S0;
S2:if(X) next_state <= S3;
else next_state <= S0;
S3:if(X) next_state <= S3;
else next_state <= S0;
default: next_state <= S0;
endcase
endmodule
Testbench
`timescale 1 ns/ 1 ns
module detector111_vlg_tst();
reg X;
reg clk;
reg rst;
wire OUT;
detector111 i1 (
.OUT(OUT),
.X(X),
.clk(clk),
.rst(rst)
);
always #10 clk = ~clk;
initial
begin
rst = 1;
clk = 0;
#10 rst = 0;
#20 X = 1;
#20 X = 0;
#20 X = 1;
#20 X = 1;
#20 X = 1;
#20 X = 1;
#20 X = 0;
#20 X = 1;
#20 X = 0;
#20 X = 1;
#20 X = 1;
#20 X = 1;
#20 X = 1;
#20 $stop;
end
initial $monitor($time,"X=%b,OUT=%b",X,OUT);
endmodule
结果
Modelsim结果如下图所示，分析可知实现了题目要求。
逻辑综合出来的电路如下图所示：即只有S3状态才会输出OUT=1。
其中的state的状态机如下图所示（RLT viewer中所示），可见其与分析中绘制的状态机一致。
2. "01110"检测器
分析
题目中关键点为一下几点：
- 检测01110，且他们不重叠。意思为要求检测到一个01110，然后从一个新的开始检测。
- 同时输入AB，那么考虑A和B哪个是01110的开始标志
- Z输出的是一个时钟周期宽度的高电平脉冲，所以要在always里进行赋值
根据题目绘制状态机如下图所示，其中S0表示01110中的0，以此类推，特别注意S1表示第一位是1即没有意义。其中输出为1即检测出01110的状态用红色标出
如果要测试所有情况，那么就是讲detector01110模块中的所有case模块都遍历到，及遍历以下所有情况，需要修改的只有testbench。而如果遍历所有情况，通过分析知道，每次AB的状态为2bit数，可以理解为4种前进的方向，然后一共5个状态，那么要遍历的次数为4^5=1024种情况，遍历即可。
case(state)
S0:case({A,B})
4'b00:state<=S0;
4'b01:state<=S01;
4'b10:state<=S0;
4'b11:state<=S011;
endcase
S01:case({A,B})
4'b00:state<=S0;
4'b01:state<=S01;
4'b10:state<=S0;
4'b11:state<=S0111;
endcase
S011:case({A,B})
4'b00:state<=S0;
4'b01:state<=S01;
4'b10:state<=S1;
4'b11:state<=S1;
endcase
S0111:case({A,B})
4'b00:state<=S0;
4'b01:state<=S01;
4'b10:state<=S0;
4'b11:state<=S1;
endcase
S1:case({A,B})
4'b00:state<=S0;
4'b01:state<=S01;
4'b10:state<=S0;
4'b11:state<=S1;
endcase
代码实现
module detector01110(
input clk,
input clr,
input A,
input B,
output reg Z
);
reg [3:0]state;
parameter S0 = 4'b0,
S01 = 4'b01,
S011 = 4'b011,
S0111 = 4'b0111,
S1 = 4'b10;//S1 is random because S01 has already existed
always@(posedge clk or negedge clr)
begin
if(!clr)
begin
state <= S0;
Z<=0;
end //for {A,B}=4'b00;
else
begin
Z = (state==S011&{A,B}==4'b10 | state==S0111&A==4'b0)?1:0;
case(state)
S0:case({A,B})
4'b00:state<=S0;
4'b01:state<=S01;
4'b10:state<=S0;
4'b11:state<=S011;
endcase
S01:case({A,B})
4'b00:state<=S0;
4'b01:state<=S01;
4'b10:state<=S0;
4'b11:state<=S0111;
endcase
S011:case({A,B})
4'b00:state<=S0;
4'b01:state<=S01;
4'b10:state<=S1;
4'b11:state<=S1;
endcase
S0111:case({A,B})
4'b00:state<=S0;
4'b01:state<=S01;
4'b10:state<=S0;
4'b11:state<=S1;
endcase
S1:case({A,B})
4'b00:state<=S0;
4'b01:state<=S01;
4'b10:state<=S0;
4'b11:state<=S1;
endcase
endcase
end
end
endmodule
Testbench
`timescale 1 ns/ 1 ns
module detector01110_vlg_tst();
reg A;
reg B;
reg clk;
reg clr;
// wires
wire Z;
detector01110 ins1 (
// port map - connection between master ports and signals/registers
.A(A),
.B(B),
.Z(Z),
.clk(clk),
.clr(clr)
);
always #10 clk = ~clk;
integer i0;
integer i1;
integer i2;
integer i3;
integer i4;
//5 layers circulation
//4^5=1024
initial
begin
clr = 0;
clk = 0;
{A,B} = 4'b00;
#15 clr = 1;
for(i0=0;i0<4;i0=i0+1)
begin
#20 {A,B} = i0;
for(i1=0;i1<4;i1=i1+1)
begin
#20 {A,B} = i1;
for(i2=0;i2<4;i2=i2+1)
begin
#20 {A,B} = i2;
for(i3=0;i3<4;i3=i3+1)
begin
#20 {A,B} = i3;
for(i4=0;i4<4;i4=i4+1)
#20 {A,B} = i4;
end
end
end
end
#50 $stop;
end
initial $monitor($time,"Z=%b",Z);
endmodule
结果
Modelsim仿真结果如下所示，经分析与预期一致
逻辑综合后的结果如下图所示：
state里的状态机如下图所示，符合预期：
