多项选择题
下面这段程序中,clk为时钟信号输入,set为复位信号,y1和y2驱动发光二极管,高电平点亮。set置0,待时钟上升沿,同步初始化;之后set置1,开始运行。则下列说法中正确的是:
module Learn6_2(clk,set,y1,y2);
input clk,set;
output reg y1,y2;
reg a1,a2;
always@(posedge clk)
begin
if(!set)
begin
a1 <= 1;
a2 <= 1;
y1 <= 1;
y2 <= 1;
end
else
begin
a1 = (~y1);
y1 = (~a1);
a2 <= (~y2);
y2 <= (~a2);
end
end
endmodule
A、y1在时钟上升沿循环亮灭
B、y1保持常亮
C、y2在时钟上升沿循环亮灭
D、y2保持常亮