Arduino Basics Cheat Sheet

1. What is Arduino?

• Arduino is an open-source electronics platform combining hardware and software.
• Microcontroller Boards: Arduino UNO, Mega, Nano, etc.
• Languages: C/C++ (with Arduino libraries).

---

2. Setting Up Arduino IDE

• Download: https://www.arduino.cc/en/software
• Install on Windows/Mac/Linux.
• Connect Board: Use USB cable.
• Select Board and Port:
  • Tools > Board > Arduino Uno
  • Tools > Port > COM (USB)

---

3. Basic Structure of Arduino Code

// Runs once when the board starts
void setup() {
  pinMode(LED_BUILTIN, OUTPUT);  // Initialize pin
}

// Loops continuously after setup
void loop() {
  digitalWrite(LED_BUILTIN, HIGH);  // Turn LED on
  delay(1000);                      // Wait 1 second
  digitalWrite(LED_BUILTIN, LOW);   // Turn LED off
  delay(1000);                      // Wait 1 second
}

Key Functions:

• setup() – Runs once when the board powers on.
• loop() – Repeats continuously.

---

4. Uploading Code

1. Write code in the Arduino IDE.
2. Click Upload (→) or press Ctrl + U.
3. The board will reset and run the code.

---

5. Pin Modes

pinMode(pin, mode);

• INPUT – Receives data (sensors).
• OUTPUT – Sends data (LEDs, motors).
• INPUT_PULLUP – Internal pull-up resistor (for switches).

---

6. Digital I/O

digitalWrite(pin, HIGH);  // Turn on
digitalWrite(pin, LOW);   // Turn off

int value = digitalRead(pin);  // Read pin (HIGH/LOW)

• HIGH – 5V (On).
• LOW – 0V (Off).

---

7. Analog I/O

Analog Read (0-1023):

int sensorValue = analogRead(A0);  // Read value from pin A0

Analog Write (PWM, 0-255):

analogWrite(9, 128);  // Write PWM signal to pin 9

---

8. Serial Communication

Serial.begin(9600);            // Start Serial at 9600 baud
Serial.println("Hello!");      // Print with newline
Serial.print("Value: ");       // Print without newline
Serial.print(sensorValue);

---

9. Control Structures

If-Else Statement:

if (sensorValue > 500) {
  digitalWrite(LED_BUILTIN, HIGH);
} else {
  digitalWrite(LED_BUILTIN, LOW);
}

For Loop:

for (int i = 0; i < 10; i++) {
  Serial.println(i);
}

While Loop:

while (digitalRead(2) == LOW) {
  Serial.println("Waiting...");
}

---

📌 10. Common Functions

---

11. Sensors and Modules

LED Blinking (Basic Example):

pinMode(LED_BUILTIN, OUTPUT);

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);
  delay(500);
  digitalWrite(LED_BUILTIN, LOW);
  delay(500);
}

Button Input:

pinMode(2, INPUT);

void loop() {
  if (digitalRead(2) == HIGH) {
    Serial.println("Button Pressed");
  }
}

Temperature Sensor (LM35):

int temp = analogRead(A0);
float temperature = (temp / 1023.0) * 500;
Serial.println(temperature);

---

12. Controlling Motors

Servo Motor (Using Servo Library):

#include <Servo.h>

Servo servoMotor;
servoMotor.attach(9);  // Attach to pin 9

void loop() {
  servoMotor.write(90);  // Move to 90 degrees
  delay(1000);
  servoMotor.write(0);   // Move to 0 degrees
  delay(1000);
}

---

13. Ultrasonic Sensor (Distance Measurement)

const int trigPin = 9;
const int echoPin = 10;

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);

  long duration = pulseIn(echoPin, HIGH);
  int distance = duration * 0.034 / 2;
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");
  delay(500);
}

---

14. Troubleshooting Tips

• Check Wiring – Ensure correct connections to pins.
• Verify Board/Port – Recheck board and port selection.
• Test with Basic Sketch – Upload a simple LED blink to verify hardware.
• Restart Arduino IDE – Sometimes restarting the IDE resolves upload issues.

---

15. Useful Arduino Libraries

#include <Servo.h>         // Servo motor control
#include <Wire.h>          // I2C communication
#include <Adafruit_Sensor.h>  // Adafruit sensor library

• Install libraries via Sketch > Include Library > Manage Libraries.

---

Example: Full Project (Temperature and LED Control)

const int tempPin = A0;
const int ledPin = 9;

void setup() {
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  int temp = analogRead(tempPin);
  float temperature = (temp / 1023.0) * 500;
  Serial.print("Temp: ");
  Serial.println(temperature);

  if (temperature > 30) {
    digitalWrite(ledPin, HIGH);
  } else {
    digitalWrite(ledPin, LOW);
  }
  delay(1000);
}