🤖 Jeremy's Arduino Lab

📟 Which device do I use?

💻 Windows computer — for coding

The Arduino IDE program and the USB cable only work on a real computer. You'll write code and run every experiment here.

📱 iPad — for reading & watching

Use the iPad to read this page and watch the ELEGOO videos while you build. (It can't run the Arduino IDE or plug into the board.)

Get Set Up

Do this once

🎯 Install the Arduino IDE on your Windows computer and make sure it can talk to your Mega2560 board.

What you need

🖥️ Windows computer 🔌 Mega2560 board 🔵 Blue USB cable (square end)

Install Arduino IDE

On the Windows computer, click one of these — the Microsoft Store version is the easiest:

🪟Get it from Microsoft StoreOne click · updates itself · Windows 10/11 ⬇️Download installer (.exe)Arduino IDE 2 · about 160 MB

Or open the official page and choose a download: arduino.cc/en/software

1
Microsoft Store → press Install. Installer (.exe) → open the downloaded file and click I Agree → Install, then Finish.
2
Open Arduino IDE (it may take a minute the first time).
3
Plug the board into the computer: the square (USB-B) end into the board, the flat (USB-A) end into the computer. A little green power light turns on.
4
In Arduino IDE: Tools → Board → Arduino AVR Boards → Arduino Mega or Mega 2560. If it offers to install “Arduino AVR Boards”, click Install.
5
Tools → Port → pick the port that appeared (something like COM3).

🛠️ No COM port showing up?

Most ELEGOO boards use a chip called CH340 that Windows needs a small driver for. Find the CH340 driver in your kit's download folder (or search “CH340 driver Windows”), install it, then unplug and replug the board and check Tools → Port again.

Make the Light Blink

★ Your first program

🎯 Upload your very first program and make the tiny built-in light blink — then make it blink your way.

Parts Needed

🔌 Mega2560 + USB cable ✨ That's it!

Wiring

No wiring needed — the Mega2560 has a small LED built in, already wired to pin 13.

The Code

// Experiment 1 — Blink
// Pin 13 has a tiny LED soldered onto the board.

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);   // get pin 13 ready to send power
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH); // LED ON  (HIGH = 5 volts)
  delay(1000);                     // wait 1000 ms = 1 second
  digitalWrite(LED_BUILTIN, LOW);  // LED OFF (LOW = 0 volts)
  delay(1000);                     // wait 1 second
}

1
In Arduino IDE, delete anything in the editor and type (or paste) the code above.
2
Click the round → Upload button (top-left). Wait for “Done uploading.”
3
Watch the board — the little LED blinks on for 1 second, off for 1 second. 🎉

🔬 How it works

setup() runs once when the board powers on. loop() runs over and over forever. digitalWrite turns a pin ON (HIGH) or OFF (LOW), and delay pauses in milliseconds (1000 = one second).

🧪 Try this

Change both 1000s to 200 and upload again — fast blink! Then make an SOS signal: 3 quick blinks, 3 slow blinks, 3 quick blinks.

A Button Switch

★★ Input + Output

🎯 Wire up a real LED and a push button. Press the button → light ON. Let go → light OFF.

Parts Needed

🍞 Breadboard 💡 LED × 1 🟫 220Ω resistor (red-red-brown) 🔘 Push button 🔗 Jumper wires

Wiring

🍞 Show realistic breadboard layout (Fritzing-style)

Holes in the same column (within one half) are joined inside the board. The button bridges the center gap; both green jumpers go to the blue (−) GND rail.

🔌 Wiring in words

LED: Pin 8 → 220Ω resistor → LED long leg (+); LED short leg (−) → GND.
Button: one leg → Pin 2; the leg diagonally across → GND.

The Code

// Experiment 2 — Button switch
const int buttonPin = 2;   // the push button
const int ledPin    = 8;   // the LED

void setup() {
  pinMode(buttonPin, INPUT_PULLUP); // built-in resistor; pressed = LOW
  pinMode(ledPin, OUTPUT);
}

void loop() {
  if (digitalRead(buttonPin) == LOW) { // button is pressed
    digitalWrite(ledPin, HIGH);        // light ON
  } else {
    digitalWrite(ledPin, LOW);         // light OFF
  }
}

🔬 How it works

digitalRead checks a pin instead of powering it. INPUT_PULLUP uses a resistor inside the chip so the pin reads HIGH normally, and LOW when you press the button (which connects it to GND). The if / else makes a decision every loop.

🧪 Try this

Turn it into a toggle: press once to turn on, press again to turn off. (Hint: you'll need a variable that remembers if the light is on, and you only flip it the moment the button is first pressed.)

Breathing Light

★★★ PWM & loops

🎯 Make the LED smoothly fade brighter and dimmer, like it's slowly breathing.

Parts Needed

🍞 Breadboard 💡 LED × 1 🟫 220Ω resistor 🔗 Jumper wires

Wiring

🍞 Show realistic breadboard layout (Fritzing-style)

Same single LED branch as Experiment 2 — just move the orange wire to Pin 9 (~) so it can fade. The green jumper goes to the blue (−) GND rail.

🔌 Wiring in words

Same as before, but the LED's resistor now connects to Pin 9 (a pin with a ~ next to it). LED short leg (−) → GND.

The Code

// Experiment 3 — Breathing light (PWM)
const int ledPin = 9;   // pin 9 has a "~" (can fade)

void setup() {
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // fade up: 0 (off) to 255 (full brightness)
  for (int b = 0; b <= 255; b++) {
    analogWrite(ledPin, b);
    delay(6);
  }
  // fade down: 255 back to 0
  for (int b = 255; b >= 0; b--) {
    analogWrite(ledPin, b);
    delay(6);
  }
}

🔬 How it works

analogWrite uses a trick called PWM: it flicks the pin on and off super fast, so the LED looks dimmer or brighter — any value from 0 to 255. A for loop counts for you, so you don't write 256 separate lines.

🧪 Try this

Make the delay(6) bigger for slow, sleepy breathing or smaller for fast. Bonus: add a second LED on another ~ pin that fades the opposite way.

Smart Night Light

★★★★ Sensors & Serial Monitor

🎯 Use a light sensor so the LED brightens when the room gets dark and dims when it's bright — all by itself. Then watch the numbers live on screen.

Parts Needed

🍞 Breadboard 🌗 Photoresistor (light sensor) 🟫 10kΩ resistor (brown-black-orange) 💡 LED + 220Ω resistor 🔗 Jumper wires

Wiring

🍞 Show realistic breadboard layout (Fritzing-style)

Left = the light-sensor divider (5V → LDR → node → 10kΩ → GND), with A0 reading the node. Right = the same LED branch as before on Pin 9 (~). Green jumpers and the black wire all meet at the blue (−) GND rail.

🔌 Wiring in words

Sensor: 5V → photoresistor → row we'll call “middle”; from “middle” → 10kΩ resistor → GND; and a wire from “middle” → A0.
LED: Pin 9 → 220Ω → LED long leg (+); LED short leg (−) → GND.

The Code

// Experiment 4 — Smart night light
const int sensorPin = A0;   // the light sensor
const int ledPin    = 9;    // LED on a "~" pin

void setup() {
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);       // open a line to the computer
}

void loop() {
  int light = analogRead(sensorPin);            // 0 = dark ... 1023 = bright
  int brightness = map(light, 0, 1023, 255, 0); // darker -> brighter LED
  analogWrite(ledPin, brightness);
  Serial.println(light);    // print the reading
  delay(50);
}

1
Upload the code, then open Tools → Serial Monitor and set it to 9600 baud (bottom-right).
2
Cover the sensor with your hand — the number drops and the LED gets brighter.
3
Shine a phone light on it — the number rises and the LED dims.

🔬 How it works

analogRead turns the sensor's voltage into a number from 0 to 1023. map rescales one range to another (here, flipping it so dark = bright LED). Serial.println sends data back to the computer so you can see what the board senses.

🧪 Try this

Watch your room's numbers, pick a “dark” value, then add an if so the LED only switches on below that number — a real automatic night light that ignores small changes.

⚠️ Lab Rules

Always put a resistor in line with an LED — a bare LED on 5V can burn out.
Build and rewire with the USB unplugged; plug it in only when you're ready to test.
Never connect 5V straight to GND — that's a short circuit.
LED legs: the long leg is + (anode); the short leg / flat side is − (cathode).
Push pins and wires in gently, and keep drinks away from the breadboard.

🏆 My Progress

#	Experiment	Level
0	Get Set Up	—
1	Make the Light Blink	★
2	A Button Switch	★★
3	Breathing Light	★★★
4	Smart Night Light	★★★★