Question

Building on a code in the Serial Monitor video, add in the ability to type the word “off” into the serial monitor and have both the red and green LEDs turn off simultaneously.

Arduino code only.... Thank You.

Answer 1

int red_led = 13;

int green_led=12;

void setup() {              
pinMode(red_led, OUTPUT); //pins are declared as output

pinMode(green_led, OUTPUT);
Serial.begin(9600);
pinMode(13,OUTPUT);

pinMode(12,OUTPUT);
}

void loop() {
if (Serial.available()){
char s=Serial.read();
Serial.println("on");
if(s=='on'){
digitalWrite(13, HIGH); // LED will be on for this condition

  digitalWrite(12, HIGH);
Serial.println("green and red_LED are ON");          
}
if(s=='off'){
digitalWrite(13,LOW); // led will be off for this condition

digitalWrite(12,LOW);
Serial.println("red_LED and green_led are OFF");
}}}

Explanation:

In this program, when we type "on" in serial monitor then both led's will be on and similarly when we type "off" they will become "off". Ensure that your system is connected to arduino board.