程序

#include <REGX52.H>

void  main() 
{
	while(1) 
	{
		if(P3_1 == 0)	//DOWN
		{
			P2_0 = 0xFE;
		}
		if(P3_1 == 1)	//UP
		{
			P2_0 = 0XFF;
		}
	};
	
}

按键的抖动问题

软件实现解决-按键的抖动问题

通过延时解决

#include <REGX52.H>

void Delay(unsigned int xms)		
{
	while(xms)
	{
		unsigned char data i, j;

		i = 2;
		j = 239;
		do
		{
			while (--j);
		} while (--i);
		xms--;
	};
}


void main() 
{
	while(1) 
	{
		if(P3_1 == 0)	//down
		{
			Delay(20);	
			while(P3_1 == 0);	//check down
			Delay(20);
			P2_0 = ~P2_0;		//change
		}
	};
	
}