本期考点
最近忙着毕业，文章写得粗糙，没有配合图，所以暂停更新这个计划，搞完毕设再更~
上期答案
【009】数字IC笔面试常见题
代码语言：javascript复制//Synchronous
module Sync_Pulse(
input clka,
input clkb,
input rst_n,
input pulse_ina,
output pulse_outb,
output signal_outb
);
//-------------------------------------------------------
reg signal_a;
reg signal_b;
reg [1:0] signal_b_r;
reg [1:0] signal_a_r;
//-------------------------------------------------------
//在clka下，生成展宽信号signal_a
always @(posedge clka or negedge rst_n)begin
if(rst_n == 1'b0)begin
signal_a <= 1'b0;
end
else if(pulse_ina == 1'b1)begin
signal_a <= 1'b1;
end
else if(signal_a_r[1] == 1'b1)
signal_a <= 1'b0;
else
signal_a <= signal_a;
end
//-------------------------------------------------------
//在clkb下同步signal_a
always @(posedge clkb or negedge rst_n)begin
if(rst_n == 1'b0)begin
signal_b <= 1'b0;
end
else begin
signal_b <= signal_a;
end
end
//-------------------------------------------------------
//在clkb下生成脉冲信号和输出信号
always @(posedge clkb or negedge rst_n)begin
if(rst_n == 1'b0)begin
signal_b_r <= 2'b00;
end
else begin
signal_b_r <= {signal_b_r[0], signal_b};
end
end
assign pulse_outb = ~signal_b_r[1] & signal_b_r[0];
assign signal_outb = signal_b_r[1];
//-------------------------------------------------------
//在clka下采集signal_b[1]，生成signal_a_r[1]用于反馈拉低signal_a
always @(posedge clka or negedge rst_n)begin
if(rst_n == 1'b0)begin
signal_a_r <= 2'b00;
end
else begin
signal_a_r <= {signal_a_r[0], signal_b_r[1]};
end
end
endmodule
