Arduino IDE Cheat Sheet

IDE Shortcuts #

Shortcut	Action
`Ctrl + R`	Verify / compile
`Ctrl + U`	Upload
`Ctrl + Shift + U`	Upload using a programmer
`Ctrl + Shift + M`	Serial Monitor
`Ctrl + T`	Auto format
`Ctrl + /`	Comment / uncomment
`Ctrl + Space`	Autocomplete
`Ctrl + click`	Go to definition
`Ctrl + F`	Find / replace
`Ctrl + Shift + I`	Library Manager
`Ctrl + Shift + B`	Boards Manager
`Ctrl + Alt + S`	Export compiled binary
`Ctrl + K`	Show the sketch folder
`Ctrl + ,`	Preferences
`Ctrl + N` / `Ctrl + O` / `Ctrl + S`	New / open / save

Sketch Structure #

const int LED = 13;

void setup() {             // runs once
  pinMode(LED, OUTPUT);
  Serial.begin(115200);
}

void loop() {              // runs forever
  digitalWrite(LED, HIGH);
  delay(500);
  digitalWrite(LED, LOW);
  delay(500);
}

Pins #

Function	Use
`pinMode(pin, OUTPUT / INPUT / INPUT_PULLUP)`	Set the pin mode
`digitalWrite(pin, HIGH / LOW)`	Output on / off
`digitalRead(pin)`	Read HIGH / LOW
`analogRead(pin)`	0–1023 (Uno, 10-bit) / 0–4095 (ESP32, 12-bit)
`analogWrite(pin, 0–255)`	PWM output (LED brightness, motor speed)
`attachInterrupt(digitalPinToInterrupt(pin), isr, RISING)`	Run a function on a pin change

Time #

Function	Use
`delay(ms)`	Pause (blocks everything)
`millis()`	Milliseconds since start (non-blocking timing)
`micros()`	Microseconds since start

unsigned long last = 0;
void loop() {
  if (millis() - last >= 1000) {   // every second, without delay()
    last = millis();
    Serial.println("tick");
  }
}

Serial #

Function	Use
`Serial.begin(115200)`	Start (match the baud rate in the monitor!)
`Serial.print(x)` / `Serial.println(x)`	Print / print + newline
`Serial.printf("T=%.1f\n", t)`	Formatted print (ESP32 / ESP8266)
`Serial.available()`	Bytes waiting to be read
`Serial.read()` / `Serial.readStringUntil('\n')`	Read input

Math & Helpers #

Function	Use
`map(x, 0, 1023, 0, 255)`	Re-scale a value
`constrain(x, 0, 100)`	Clamp
`random(min, max)`	Random number (`randomSeed(analogRead(A0))` first)
`tone(pin, freq, ms)` / `noTone(pin)`	Buzzer
`F("text")`	Keep strings in flash, saves RAM on AVR

Communication Libraries #

Library	Use
`Wire.h`	I²C (sensors, OLED displays): `Wire.begin()`
`SPI.h`	SPI (SD cards, TFT displays)
`WiFi.h`	Wi-Fi on ESP32
`EEPROM.h` / `Preferences.h`	Store data permanently (AVR / ESP32)

Data Types #

Type	AVR (Uno)	ESP32
`int`	16-bit	32-bit
`long`	32-bit	32-bit
`float` / `double`	32-bit / 32-bit	32-bit / 64-bit
`uint8_t`, `int16_t`, `uint32_t`	Exact sizes, use these when it matters

Boards & Troubleshooting #

Problem / task	Fix
Add ESP32 boards	Preferences → Additional boards URLs: `https://espressif.github.io/arduino-esp32/package_esp32_index.json` → Boards Manager → install esp32
No port shows up	Install the USB driver (CH340 or CP210x), try another (data) cable
ESP32 "Failed to connect"	Hold the BOOT button when "Connecting…" appears
Garbage in Serial Monitor	Baud rate doesn't match `Serial.begin()`
Sketch too big / low memory	Use `F()` strings, smaller types, fewer libraries