题解 | #信号发生器#
信号发生器
https://www.nowcoder.com/practice/39f6766689cc448e928a0921d1d1f858
`timescale 1ns/1ns
module signal_generator(
input clk,
input rst_n,
input [1:0] wave_choise,
output reg [5:0]wave
);
reg [5:0] cnt;
wire flag_fang,flag_juchi,flag_sanjiao;
reg [1:0] wave_choise_r;
wire f_change;
//把wave选择存起来，看看选择是否变更
always@ (posedge clk or negedge rst_n)
begin
if(!rst_n) wave_choise_r <= 0;
else begin wave_choise_r <= wave_choise; end
end
assign f_change = wave_choise!=wave_choise_r?1:0;
//计时器的正常计数，用flag和wave_choise 来确定如何计数
always@ (posedge clk or negedge rst_n)
begin
if(!rst_n)
begin
cnt <= 0;
wave <= 0;
end
else if(f_change == 1)
begin
case(wave_choise)
0: begin cnt <= 0; wave <= 0; end
1: begin cnt <= 0; wave <= 0; end
2: begin
if(wave>=1) begin cnt = 40 - wave+1; wave = wave-1 ; end
else cnt = 40 - wave;
end
endcase
end
else if(f_change == 0)
begin
case(wave_choise)
0: begin
wave = flag_fang?0:20;
if(wave_choise==0 && cnt == 19) begin cnt<=0; end
else begin cnt <= cnt + 1 ; end
end
1: begin
if(wave_choise==1 && cnt == 20) begin cnt<=0; end
else begin cnt <= cnt + 1 ; end
wave <= flag_juchi?0:1+cnt;
end
2: begin
if(wave_choise==2 && cnt == 39) begin cnt<=0; end
else begin cnt <= cnt + 1 ; end
if(flag_sanjiao) wave <= wave + 1;
else wave <= wave - 1;
end
endcase
end
end
assign flag_fang = (cnt>=0 && cnt<9)||cnt==19||cnt==0?1:0;//1时代表空输出，0时代表满输出
assign flag_juchi = (cnt==20)?1:0;//1时代表到顶了，0时代表没有到顶
assign flag_sanjiao = (cnt>=0 && cnt<=19)?1:0;//1时代表着增，0时代表着减，置位的时候也关注一下这里吧。同时设置wave和cnt;
endmodule
