• 2022-05-31
    在按键中断实验中,轻触键key0,key1,key2和key3分别与pio[0],pio[1],pio[2]和pio[3]相连,即key0接pio的低位,key3接pio的高位。已知按下轻触键,key=0;不按下,key=1。如果key3按下,执行以下语句后,变量edge_cap_value的值是()。edge_cap_value=IORD_ALTERA_AVALON_PIO_EDGE_CAP (KEY_PIO_BASE);
    A: edge_cap_value=0x1;
    B: edge_cap_value=0x2;
    C: edge_cap_value=0x4;
    D: edge_cap_value=0x8;