#include <wiringPi.h>
#include <stdio.h>

#define LED_PIN  26
#define BTN_PIN  27

#define DELY_MS  100

int main(void)
{
    wiringPiSetup();
    pinMode(LED_PIN, OUTPUT);
    pinMode(BTN_PIN, INPUT);

    digitalWrite(LED_PIN, HIGH);
    pullUpDnControl(BTN_PIN, PUD_UP);

    while(1)
    {
        //检测按钮是否被按下
        if(digitalRead(BTN_PIN) == 0)
        {
            //led GPIO引脚置低电平,灯亮
            digitalWrite(LED_PIN, LOW);
            printf("O\n");
        }
        else
        {
            //led GPIO引脚置高电平,灯灭
            digitalWrite(LED_PIN, HIGH);
            printf("X\n");
        }

        //增加延时函数,减少cpu消耗
        delay(DELY_MS);
    }

    return 0;
}