What I wanted to learn, and why it interested me: I want to control a fan on and off remotely.

Process and reflection: 

I first followed the technical exercise to build basic communication between 2 arduinos. When the LED is blinking that means the receiver arduino is receving signals from the transmitter. Then I added a potentiometer to the transmitter as input to control the LED brightness from the receiver. Then I wanted to use a fan as a creative output and ultrasonic ranger as an input. I learned to wire and code both of them in class. One of the bigger takeaway is that both arduinos need to be connected to the same power and ground!! The fan with ultrasonic input can be finicky sometimes since it can't always stop entirely when an object is close. 

I definitely enjoy this small exercise since I have a lot of freedom and the pace is good enough for me to enjoy learning. I don't know what exactly I want to do for the second project yet but I am sure this exploration is helpful. I like using fan as an output a lot though!

Receiver: 

/*

   60-223 Intro to Physical Computing, fall 2025

   Domain-specific Skill Building exercise: remote control air

 This is connected two arduinos. Transmiter with ultrasonic ranger input. Receiver with fan output.

 Depends on the distance of an object, when the object is closer, the fan will stop. If the object distance is far,

 the fan will continue to blow.

   Pin mapping:

   Arduino pin | role  | details

   ------------------------------

   9             output  external fan

*/

int fanPin = 9;

int inVal = 0;

void setup() {

 // put your setup code here, to run once:

 pinMode(fanPin, OUTPUT);

 Serial.begin(9600);

}

void loop() {

 // put your main code here, to run repeatedly:

 while (Serial.available()) {

   int inVal = Serial.parseInt();  // read the value as an integer

   // int mapVal = map(inVal, 0, 50, 0, 255);

   if (inVal < 10) {

     analogWrite(fanPin, 0);

   } else {

     analogWrite(fanPin, 200);

   }

 }

}

Transimiter: 

/*

   60-223 Intro to Physical Computing, fall 2025

   Domain-specific Skill Building exercise: remote control air

 This is connected two arduinos. Transmiter with ultrasonic ranger input. Receiver with fan output.

 Depends on the distance of an object, when the object is closer, the fan will stop. If the object distance is far,

 the fan will continue to blow.

   Pin mapping:

   Arduino pin | role  | details

   ------------------------------

   9             input   echo pin

10            output  trigger pin

Code example credit: https://create.arduino.cc/projecthub/Isaac100/getting-started-with-the-hc-sr04-ultrasonic-sensor-036380

*/

const int trigPin = 10;

const int echoPin = 9;

float duration, distance;

void setup() {

 pinMode(trigPin, OUTPUT);

 pinMode(echoPin, INPUT);

 Serial.begin(9600);

}

void loop() {

 digitalWrite(trigPin, LOW);

 delayMicroseconds(2);

 digitalWrite(trigPin, HIGH);

 delayMicroseconds(10);

 digitalWrite(trigPin, LOW);

 duration = pulseIn(echoPin, HIGH);

 distance = (duration*.0343)/2;

 distance = constrain(distance,0,50);

 Serial.print("Distance: ");

 Serial.println(distance);

 delay(100);

}