[DIY] Arduino : Serial Monitor - String Operations

Curious on how does Arduino Serial Monitor interacts and processes the string read and Output Functions.

Activity: Use Serial Port to blink Red, Green or Yellow LED one at a time.

Wiring Diagram:

Bill of Material:

Arduino IDE Code: 

int redPin = 13;
int greenPin = 11;
int yellowPin = 9;

String msg = "Hi!, which LED color would you like to glow? ";
String ledPick;
String msg2 = " blinking done!";

void setup() {
  Serial.begin(9600);
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(yellowPin, OUTPUT);
}

void loop() {
  Serial.println(msg);

  while (Serial.available() == 0) {
    // wait for input
  }

  ledPick = Serial.readString();

  if (ledPick == "RED" || ledPick == "red" || ledPick == "Red") {
    digitalWrite(redPin, HIGH);
    digitalWrite(greenPin, LOW);
    digitalWrite(yellowPin, LOW);
  }

  if (ledPick == "GREEN" || ledPick == "green" || ledPick == "Green") {
    digitalWrite(redPin, LOW);
    digitalWrite(greenPin, HIGH);
    digitalWrite(yellowPin, LOW);
  }

  if (ledPick == "YELLOW" || ledPick == "yellow" || ledPick == "Yellow") {
    digitalWrite(redPin, LOW);
    digitalWrite(greenPin, LOW);
    digitalWrite(yellowPin, HIGH);
  }

  Serial.print(ledPick);
  Serial.println(msg2);
}