PIC16F877A 的IO口输入和输出 单按键输入，单LED点亮

/*

按键连接RB1，点亮LED ，PORTA RA0 控制输出。按一次点亮，再按一次熄灭，如此循环。

RB外接上拉电阻。

*/

#include

 #define uchar unsigned char

#define uint unsigned int

// CONFIG

#pragma config FOSC = HS        //

#pragma config WDTE = OFF       // Watchdog Timer Enable bit (WDT disabled)

#pragma config PWRTE = OFF      // Power-up Timer Enable bit (PWRT disabled)

#pragma config BOREN = ON       // Brown-out Reset Enable bit (BOR enabled)

#pragma config LVP = ON         // Low-Voltage (Single-Supply) In-Circuit Serial Programming Enable bit (RB3/PGM pin has PGM function; low-voltage programming enabled)

#pragma config CPD = OFF        // Data EEPROM Memory Code Protection bit (Data EEPROM code protection off)

#pragma config WRT = OFF        // Flash Program Memory Write Enable bits (Write protection off; all program memory may be written to by EECON control)

#pragma config CP = OFF         // Flash Program Memory Code Protection bit (Code protection off)

uchar count;

void delay(uint x)

{

    uint y,z;

    for(y=x;y>0;y--)

        for(z=25;z>0;z--);

}

void Init_GPIO()

{

    TRISA = 0X00;   //  RA0 output direction

    PORTA=0X00;

    TRISB = 0x02;  // RB1 input 

    PORTB = 0x00;

}

void Keyscan()

{

    //temp = PORTB&0x02;

    if(RB1==0)

    {

        delay(200);           // delay time 根据机械按键的抖动情况调整，

        if(RB1==0)

        {

            count++;

        }

    }

}

void main(void)

{

    count = 0;

    Init_GPIO();

    while(1)

    {

        Keyscan();

        if((count%2)==1)

        {

            PORTA=0x01;

        }

        else

            PORTA = 0x00;

    }

}