ESP32 DevKit Board

01Quick Facts

• Brain Classic ESP32-WROOM module on common DevKit boards
• Logic level 3.3 V GPIO
• Programming USB to serial
• Wireless 2.4 GHz Wi-Fi plus Bluetooth/BLE
• Best start ESP32-WROOM DevKit
• Arduino support ESP32 board package

How It Works

02Technical Specifications

Arduino library: Arduino ESP32 board package

03Pinout

• 5V / VIN USB power rail 5 V modules or board input Not a GPIO. Use carefully and do not feed 5 V into signal pins.
• 3V3 Regulated output Small 3.3 V modules Limited current and board-dependent. Do not power motors, pumps, relays, or large LED loads from this pin.
• GND Ground reference All signal-sharing circuits Most external sensors, drivers, and modules need a shared ground/reference with the ESP32.
• EN Enable/reset Usually left alone Pulling EN low resets the chip.
• GPIO0 Boot strapping pin Avoid for first projects Holding it low during reset enters bootloader mode.
• GPIO2 GPIO with boot considerations LED examples on some boards Can affect boot on some boards; use carefully.
• GPIO4, 5, 16, 17, 18, 19, 21, 22, 23 General GPIO Sensors and outputs Good beginner choices for many projects when they are not already used by your board or shield.
• GPIO25, 26, 27, 32, 33 GPIO with ADC support Analog sensors or digital signals Useful classic ESP32 choices when you want ADC1 analog input and Wi-Fi in the same project.
• GPIO21 Default I2C SDA OLED/BME280 SDA Common default for I2C examples; I2C pins are configurable in code.
• GPIO22 Default I2C SCL OLED/BME280 SCL Common default clock line for I2C examples; not the only possible SCL pin.
• GPIO34-39 Input-only pins Externally driven analog or digital inputs Classic ESP32 input-only pins. They cannot drive LEDs, relays, motors, or other outputs and have no internal pull-up or pull-down resistors.
• GPIO32-39 Common ADC1 pins Analog sensors Prefer ADC1 for Wi-Fi sensor projects on classic ESP32 because ADC2 is restricted while Wi-Fi is active.
• TX0/RX0 USB serial pins Programming/logging Avoid using them for beginner circuits while debugging over USB.
• GPIO0, GPIO2, GPIO12, GPIO15 Boot strapping pins Avoid for first projects External wiring can hold the wrong level during reset and prevent boot on classic ESP32 boards.

04Wiring Diagram

Start with one safe output circuit before connecting complex modules. Use USB for board power, keep GPIO signals within 3.3 V logic levels, connect shared ground where signals cross between boards, and never connect 5 V signals directly to ESP32 GPIO pins.

An external LED on GPIO16 is more portable than assuming every DevKit has the same onboard LED. It teaches the most important pattern: GPIO drives a small signal, a resistor limits current, and ground completes the circuit.

1. 1

   Unplug USB before wiring.

2. 2

   Place the ESP32 DevKit so each side of pins sits on a different breadboard half.

3. 3

   Install the ESP32 board package in Arduino IDE.

4. 4

   Connect the board with a known USB data cable, not a charge-only cable.

5. 5

   Select the appropriate ESP32 board profile and the correct COM/serial port.

6. 6

   Connect a 220 ohm resistor from GPIO16 to the LED long leg.

7. 7

   Connect the LED short leg to GND.

8. 8

   Upload the blink code and confirm the external LED changes state.

9. 9

   If upload stays on Connecting, hold BOOT while upload begins, then release when writing starts.

10. 10

    Open Serial Monitor at 115200 baud to confirm the sketch is running.

11. 11

    For sensors, connect VCC to the voltage required by that component and keep any signal into ESP32 GPIO at 3.3 V logic.

12. 12

    Always connect module GND to ESP32 GND when the module exchanges signals with the board.

05Code Examples

Use the same wiring with Arduino IDE, PlatformIO, or ESP-IDF. Start with Arduino, then graduate when you need a larger project structure.

#define LED_PIN 16

void setup() {
  Serial.begin(115200);
  pinMode(LED_PIN, OUTPUT);
  Serial.println("ESP32 DevKit external LED blink test started");
}

void loop() {
  digitalWrite(LED_PIN, HIGH);
  Serial.println("LED ON");
  delay(500);

  digitalWrite(LED_PIN, LOW);
  Serial.println("LED OFF");
  delay(500);
}

#include <Arduino.h>
#define LED_PIN 16

void setup() {
  Serial.begin(115200);
  pinMode(LED_PIN, OUTPUT);
  Serial.println("ESP32 DevKit external LED blink test started");
}

void loop() {
  digitalWrite(LED_PIN, HIGH);
  Serial.println("LED ON");
  delay(500);

  digitalWrite(LED_PIN, LOW);
  Serial.println("LED OFF");
  delay(500);
}

// ESP-IDF starter structure for this component.
// Keep the wiring from the pinout section, then move the read/write logic into app_main().

#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"

void app_main(void) {
  printf("ESP32 DevKit Board ready\n");
  while (true) {
    // Add component read/write code here.
    vTaskDelay(pdMS_TO_TICKS(1000));
  }
}