Week 8: Switch – Healthy Screen Distance

Concept

For this week’s assignment, I designed a simple switch to be positioned in front of a screen, like a laptop. This switch uses an HC-SR04 distance sensor and an Arduino board to control either a red or green LED. When the user is at a healthy distance from the screen—set to 50 cm or more—the green LED lights up. If the user gets too close, the red LED turns on as a warning to move back. This setup helps promote good screen-distance habits to protect eye health.

To implement the logic, I modified an example code for Sensors from the Arduino IDE. Below is a demonstration video for my switch.

Code

void setup() 
{
  // initialize serial communication:
  Serial.begin(9600);
  pinMode(trigPin,OUTPUT);
  pinMode(echoPin,INPUT);
  pinMode(GreenLED, OUTPUT);
  pinMode(RedLED, OUTPUT);
  
}
void loop() 
{
  long duration, inches, cm;
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  cm = microsecondsToCentimeters(duration);
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();
  // Controlling LEDs from Distances
  if(cm<50 )
  {
     digitalWrite(GreenLED, LOW);
     digitalWrite(RedLED, HIGH);
  }else
  {
   digitalWrite(GreenLED, HIGH);
  digitalWrite(RedLED, LOW);
  }
  delay(100);
}

long microsecondsToInches(long microseconds) 
{
  return microseconds / 74 / 2;
}

long microsecondsToCentimeters(long microseconds) 
{
  return microseconds / 29 / 2;
}

 

Reflection for future works

I have gained knowledge on how Simple switches are fundamental devices used to control the flow of current in a circuit.  It was also interesting to use the HC-SR04  sensor and see how it works. Going forward, I hope to use switches in combination with other logics to design complex and interesting projects.