Getting Started with ESP32: GPIO, WiFi, and Your First Project

The ESP32 is the most capable entry-level microcontroller available. Dual-core 240 MHz, WiFi, Bluetooth, 34 GPIO pins, under $5. Here's how to go from unboxing to your first WiFi-connected project.

Which Board?

The ESP32 DevKitC (38-pin) is the standard. Most tutorials use it. All pins broken out with clear labels.

Setting Up Arduino IDE

1. Download Arduino IDE from arduino.cc
2. In Preferences, add to Board Manager URLs: https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
3. Tools → Board Manager → search 'esp32' → install 'esp32 by Espressif Systems'
4. Tools → Board → ESP32 → 'ESP32 Dev Module'
5. Select your COM port

First Upload: Blink

void setup() {
  pinMode(2, OUTPUT);
}
void loop() {
  digitalWrite(2, HIGH); delay(1000);
  digitalWrite(2, LOW);  delay(1000);
}

If upload fails, hold the BOOT button while clicking upload, release when 'Connecting...' shows.

GPIO Key Points

• GPIO 0, 2, 15: Boot-mode pins — avoid as inputs at startup
• GPIO 34–39: Input-only, no pullup/pulldown
• ADC2 pins: Unavailable when WiFi active — use ADC1 (GPIO 32–39)
• 3.3V logic: ESP32 is NOT 5V tolerant

See the full ESP32 DevKitC pinout reference on this site.

Connect to WiFi

#include <WiFi.h>
void setup() {
  Serial.begin(115200);
  WiFi.begin("SSID", "password");
  while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); }
  Serial.println("\nConnected! IP: " + WiFi.localIP().toString());
}

Common Problems

Port not detected: Install CP2102 or CH340 USB driver. Upload fails: Hold BOOT button during upload start. WiFi won't connect: ESP32 only supports 2.4 GHz. Crashes on WiFi + ADC: Use ADC1 pins (GPIO 32–39) when WiFi is active.