AVR读键盘语句用switch

int main(void)

{
DDRD &= ~(1 << 6);//设置为输入
DDRD &= ~(1 << 3);//设置为输入
DDRD &= ~(1 << 7);//设置为输入
PORTD |= (1 << 6);//打开上啦电阻
PORTD |= (1 << 7);//打开上啦电阻
DDRA |= (1 << 3);//设置为输出
DDRB |= (1 << 0);//设置为输出
DDRB |= (1 << 1);//设置为输出
PORTA &= ~(1 << 3);//关蜂鸣器

while(1)
{

switch(PIND & 0b11000000)
{
case 0b10000000:
{
PORTB |= (1 << 0);
PORTA |= (1 << 3);
break;
}
case 0b01000000:
{
PORTB |= (1 << 1);
break;
}
default:
{
PORTA &= ~(1 << 3);
PORTB = 0;
}
}
}

}