Getting started

What you need

• A board, such as an Arduino Uno or an ESP32 development board
• A USB cable that carries data, not only power
• A computer with the free Arduino IDE installed

Your first sketch: blink

Most boards have a small LED built in. This sketch turns it on and off every second.

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

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);  // LED on
  delay(1000);                      // wait one second
  digitalWrite(LED_BUILTIN, LOW);   // LED off
  delay(1000);
}

Steps

1. Plug the board into your computer with the USB cable.
2. Open the Arduino IDE and choose your board and port from the Tools menu. For an ESP32, first add its board package.
3. Paste in the sketch (the IDE also has a Blink example under File, Examples, Basics).
4. Press Upload and watch the LED blink.

Safe next steps

• Add an external LED, always with a resistor in series.
• Read a button with digitalRead().
• Stay with low-voltage, battery or USB power. Do not connect a board to mains electricity.
• Check voltage: 5 volts on an Uno, 3.3 volts on an ESP32.
• Change one thing at a time, so you know what caused any problem.