51单片机学习--LED流水灯

#include 
#include 

void Delay1ms(int t)		//@11.0592MHz
{
	while(t --) {
		unsigned char i, j;

		_nop_(); //需要添加头文件
		i = 2;
		j = 199;
		do
		{
			while (--j);
		} while (--i);
	}
}//延时1ms执行t次


void main()
{
	while(1)
	{
		P2 = 0xFE; //1111 1110
		Delay1ms(500);
		
		P2 = 0xFD; //1111 1101
		Delay1ms(500);
		
		P2 = 0xFB; //1111 1011
		Delay1ms(500);
		
		P2 = 0xF7; //1111 0111
		Delay1ms(500);
		
		P2 = 0xEF; //1110 1111
		Delay1ms(500);
		
		P2 = 0xDF; //1101 1111
		Delay1ms(500);
		
		P2 = 0xBF; //1011 1111
		Delay1ms(500);
		
		P2 = 0x7F; //0111 1111
		Delay1ms(500);
	}
}

延时代码可通过软件生成，系统频率要和开发板的晶振频率相对应。