Question

write a code in C on RaspberryPi to have an LED light turn on and off using a push button

Answer 1

Answer :

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I am writing code for Raspberry pi 3 .

Hardware connection :

1. LED 3.3v connected to GPIO 2 which is BCM2 (SDA ) with 100 ohm resistor .

2. PUSH button 1 connected to GPIO 3 which is SCL pin . (for turn on led)

3. PUSH button 2   connected to GPIO17 to turn off led

Program Plan :

1. set GPIO2 led pin as OUTPUT .

2. set GPIO3 push button pin as INPUT and set pullup resistor high to detect low on push button pin .

3. run a while loop where we will check continuously push button.

4. in if statement will check for push button pressed if pressed we will get 0 of pin status and will set LED high .

5. if second button pressed turn off led.

Code :

#include <wiringPi.h>           //hardware  definition file
#include <stdio.h>

#define LED    2    //GPIO 2
#define OnButton 3      //GPIO 3   to turn on led 
#define OffButton 17   //GPIO 17  to turn off led

int main(void)
{

    
    pinMode(LED, OUTPUT);   //set o/p to led pin 
    pinMode(OnButton, INPUT);  //set input on button pin 
    pinMode(OffButton, INPUT);  //set input on button pin 

    pullUpDnControl(OnButton, PUD_UP);             //pull up set to detect low on pin 
    pullUpDnControl(OffButton, PUD_UP);             //pull up set to detect low on pin 
    while(1){ 
    
        if(digitalRead(OnButton) == 0){ //button presses 
            digitalWrite(LED, HIGH);   //Set LED high 
           delay(100); //debounce time 
          
        }
        else if(digitalRead(OffButton)==0){
             digitalWrite(LED,LOW);  //turn off led
             delay(100); //debounce time 
        }
    }

    return 0;
}