3.c

51单片机及C语言入门源代码

#include <AT89X51.h> //预处理命令

void main(void) //主函数名
{
  unsigned int a; //定义变量a为unsigned int类型
unsigned char b; //定义变量b为unsigned char类型

  do
		{ //do while组成循环
			for (a=0; a<65535; a++)
				P1_0 = 0; //65535次设P1.0口为低电平，点亮LED
			P1_0 = 1; //设P1.0口为高电平，熄灭LED

			for (a=0; a<30000; a++); //空循环

			for (b=0; b<255; b++)
				P1_1 = 0; //255次设P1.1口为低电平，点亮LED
			P1_1 = 1; //设P1.1口为高电平，熄灭LED


			for (a=0; a<30000; a++); //空循环
		}
	while(1);
}