题解 | #序列发生器#
序列发生器
https://www.nowcoder.com/practice/1fe78a981bd640edb35b91d467341061
序列发生器多种解法：
解法1、二阶段moore状态机：
注意点：
1、就离谱，状态机都写不利索了。是把下一状态赋值给当前状态。state <= n_state;
2、还有个问题，就是多了一个idle状态，为什么必须要一个idle状态？本题加idle是因为牛客网题目的问题吗？这样第一次输出变成了0001001？
`timescale 1ns/1ns module sequence_generator( input clk, input rst_n, output reg data ); parameter [2:0] s0 = 3'd0, s1 = 3'd1, s2 = 3'd2, s3 = 3'd3, s4 = 3'd4, s5 = 3'd5, idle = 3'd6; reg [2:0] state, n_state; always@(posedge clk, negedge rst_n) begin if(~rst_n) begin n_state <= s0; end else begin n_state <= state; end end always@(posedge clk, negedge rst_n) begin if(~rst_n) begin state <= idle; end else begin state <= n_state; end end always @ (*) begin case(state) idle: begin n_state <= s0; data <= 1'b0; end s0: begin n_state <= s1; data <= 1'b0; end s1: begin n_state <= s2; data <= 1'b0; end s2: begin n_state <= s3; data <= 1'b1; end s3: begin n_state <= s4; data <= 1'b0; end s4: begin n_state <= s5; data <= 1'b1; end s5: begin n_state <= s0; data <= 1'b1; end default: begin n_state <= s0; data <= 1'b0; end endcase end endmodule
一开始没想出来
注意点：
1、在复位时赋初值，等效初始化，提供了一个思路，有时候初始化可以用复位赋初值代替
`timescale 1ns/1ns
module sequence_generator(
input clk,
input rst_n,
output reg data
);
//方法2：移位
reg [5:0] seque;
always@(posedge clk, negedge rst_n) begin
if(~rst_n) begin
seque <= 6'b001011;
end
else begin
seque <= {seque[4:0], seque[5]};
end
end
always@(posedge clk, negedge rst_n) begin
if(~rst_n) begin
data <= 1'b0;
end
else begin
data <= seque[5];
end
end
endmodule
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