ESP32 Pinout Diagram: Complete Pin Configuration Guide 2026

Introduction

Understanding the ESP32 pinout is essential before building any project.

Each pin has a specific function, and using the wrong pin can:

• ❌ Damage your components
• ❌ Break your WiFi connection
• ❌ Cause your code to fail silently
• ❌ Waste hours of debugging

In this complete pinout guide, I'll show you:

• Detailed pinout diagram
• What each pin does
• Which pins to use and which to avoid
• Pin specifications and limits
• Real project examples

By the end, you'll confidently use any ESP32 pin!

---

ESP32 Board Overview

The ESP32 comes in different variants:

Variant	Pins	Size	Most Common
ESP32 Dev Module	30 pins	Standard	✓ Yes
ESP32 WROOM-32	38 pins	Larger	Industrial
ESP32-S3	48 pins	Newer	Latest
ESP32-C3	22 pins	Tiny	IoT focused

This guide focuses on the most popular: ESP32 Dev Module (30 pins)

---

ESP32 Pinout Diagram

Top Row (Left to Right)

GND | D35 | D34 | D39 | D36 | D3 | D1 | D22 | D21 | GND
 ↓    ↓    ↓    ↓    ↓   ↓   ↓    ↓    ↓    ↓
[==================ESP32 DEV MODULE==================]
 ↑    ↑    ↑    ↑    ↑   ↑   ↑    ↑    ↑    ↑
D23 | D19 | D18 | D5 | D17 | D16 | D4 | D0 | D2 | GND

Complete Pinout List

Pin	Name	Function	Notes
1	GND	Ground	Connect to negative
2	D35	Input only	ADC, cannot use as output
3	D34	Input only	ADC, cannot use as output
4	D39	Input only	ADC, cannot use as output
5	D36	Input only	ADC, cannot use as output
6	D3	GPIO	Can be used as input/output
7	D1	GPIO	Also TX0 (debugging)
8	D22	GPIO	Can be used freely
9	D21	GPIO	Can be used freely
10	GND	Ground	Connect to negative
11	D23	GPIO	Can be used freely
12	D19	GPIO	SPI pins (be careful)
13	D18	GPIO	SPI pins (be careful)
14	D5	GPIO	Can be used freely
15	D17	GPIO	I2C SDA pin
16	D16	GPIO	I2C SCL pin
17	D4	GPIO	Can be used freely
18	D0	GPIO	Strapping pin (careful)
19	D2	GPIO	Can be used freely
20	GND	Ground	Connect to negative
21	D32	ADC	Can be input only
22	D33	ADC	Can be input only
23	D25	DAC	Can output analog voltage
24	D26	DAC	Can output analog voltage
25	D27	GPIO	Can be used freely
26	D14	GPIO	ADC pin
27	D12	GPIO	ADC pin (careful)
28	GND	Ground	Connect to negative
29	D13	GPIO	ADC pin
30	D15	GPIO	Can be used freely

---

Pin Types Explained

GPIO Pins (General Purpose Input/Output)

What they are: Pins you can control freely for digital signals

Safe GPIO pins to use:

• D0, D2, D4, D5, D15, D16, D17, D18, D19, D21, D22, D23, D25, D26, D27, D32, D33

Example:

const int LED_PIN = 5;  // Use D5 for LED

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

void loop() {
  digitalWrite(LED_PIN, HIGH);
  delay(1000);
  digitalWrite(LED_PIN, LOW);
  delay(1000);
}

ADC Pins (Analog Digital Conversion)

What they are: Pins that read analog voltages (0-3.3V)

ADC pins available:

• A0 (D36), A3 (D39), A4 (D32), A5 (D33)
• A6 (D34), A7 (D35)
• A10 (D4), A11 (D0), A12 (D2)
• A13 (D15), A14 (D13), A15 (D12), A16 (D14)

Example:

const int SENSOR_PIN = A4;  // D32

void setup() {
  Serial.begin(115200);
}

void loop() {
  int sensorValue = analogRead(SENSOR_PIN);
  Serial.println(sensorValue);  // 0-4095
  delay(100);
}

DAC Pins (Digital Analog Conversion)

What they are: Pins that output analog voltages (0-3.3V)

DAC pins available:

• D25 (DAC1)
• D26 (DAC2)

Example:

const int DAC_PIN = 25;

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

void loop() {
  analogWrite(DAC_PIN, 128);  // 0-255, outputs ~1.65V
  delay(1000);
}

Input-Only Pins

What they are: Pins that can ONLY read, not write

Input-only pins:

• D34, D35, D36, D39

Problem: These pins have no output capability

Solution: Use only as inputs

const int BUTTON_PIN = 34;

void setup() {
  pinMode(BUTTON_PIN, INPUT);
}

void loop() {
  int buttonState = digitalRead(BUTTON_PIN);
  Serial.println(buttonState);
}

Strapping Pins (Avoid or Use Carefully)

What they are: Pins used for boot mode detection

Strapping pins:

• D0 (pulls HIGH to run normally)
• D2 (pulls LOW to run normally)
• D5 (pulls HIGH to run normally)
• D12 (pulls LOW to run normally)

Problem: Pulling them wrong during boot can prevent program upload

Solution: Avoid using them, or use only as OUTPUT after boot

// Avoid:
const int BAD_PIN = 0;

// Better:
const int GOOD_PIN = 22;

---

Pins to AVOID

Pin	Reason	Risk
D6-D11	Flash memory	Program gets corrupted
D37-D38	USB JTAG	Debugging gets broken
EN	Reset pin	Can't upload code
GND	Ground	Shorts circuit
5V	Power	Can burn board

---

Power Pins

Pin	Voltage	Purpose
3V3	3.3V	Power input (up to 500mA)
GND	0V	Ground (negative)
5V	5V	Power input (from USB)
EN	Reset	Press to restart

Important: ESP32 runs on 3.3V, NOT 5V!

Never connect 5V sensors directly to GPIO pins.

---

Pin Functions Reference

UART Pins (Serial Communication)

TX0 = D1 (transmit)
RX0 = D3 (receive)

Use for debugging:

Serial.begin(115200);
Serial.println("Hello!");

SPI Pins (High-Speed Communication)

MOSI = D23
MISO = D19
SCK  = D18
CS   = D5 (configurable)

Use with SD card, displays:

// Usually configured automatically
// by library

I2C Pins (Sensor Communication)

SDA = D21 (data)
SCL = D22 (clock)

Use with sensors:

#include <Wire.h>

void setup() {
  Wire.begin(21, 22);  // SDA, SCL
}

PWM Pins (Pulse Width Modulation)

All GPIO pins support PWM for:

• LED brightness control
• Motor speed control
• Servo control

const int LED_PIN = 5;
const int PWM_CHANNEL = 0;
const int FREQUENCY = 5000;
const int RESOLUTION = 8;

void setup() {
  ledcSetup(PWM_CHANNEL, FREQUENCY, RESOLUTION);
  ledcAttachPin(LED_PIN, PWM_CHANNEL);
}

void loop() {
  // Brightness from 0-255
  for(int i = 0; i < 256; i++) {
    ledcWrite(PWM_CHANNEL, i);
    delay(10);
  }
}

---

Real Wiring Examples

Example 1: LED Connection

ESP32 D5 ──[220Ω]──[LED+]
             LED- ──GND

Code:

const int LED_PIN = 5;

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

void loop() {
  digitalWrite(LED_PIN, HIGH);
  delay(1000);
  digitalWrite(LED_PIN, LOW);
  delay(1000);
}

Example 2: Button Connection

ESP32 D4 ──[10kΩ]──3.3V
ESP32 D4 ──[Button]──GND

Code:

const int BUTTON_PIN = 4;

void setup() {
  pinMode(BUTTON_PIN, INPUT);
}

void loop() {
  if(digitalRead(BUTTON_PIN) == LOW) {
    Serial.println("Button pressed!");
  }
  delay(100);
}

Example 3: Temperature Sensor (I2C)

Sensor VCC ──3.3V
Sensor GND ──GND
Sensor SDA ──D21
Sensor SCL ──D22

Code:

#include <Wire.h>

void setup() {
  Wire.begin(21, 22);
}

void loop() {
  // I2C communication
}

Example 4: Analog Sensor

Sensor OUT ──D32 (ADC)
Sensor VCC ──3.3V
Sensor GND ──GND

Code:

const int ANALOG_PIN = 32;

void loop() {
  int value = analogRead(ANALOG_PIN);  // 0-4095
  float voltage = value * 3.3 / 4095;
  Serial.println(voltage);
}

---

ESP32 Pin Specifications

Electrical Ratings

Spec	Value
Operating Voltage	3.3V
Input Voltage	5-6V (via USB)
GPIO Output Current	40mA per pin
GPIO Input Current	None
Digital Output Range	0-3.3V
Analog Input Range	0-3.3V
ADC Resolution	12-bit (0-4095)
DAC Resolution	8-bit (0-255)

Maximum Current Limits

Single pin:        40 mA max
All pins total:   1200 mA max
3.3V regulator:    600 mA max

⚠️ Warning: Don't exceed these limits or you'll damage the ESP32!

---

Pin Selection Guide

For LEDs

• Best: D2, D4, D5, D22, D23, D27
• Avoid: Input-only pins, D0, D12

For Buttons

• Best: D4, D14, D15, D32, D33
• Avoid: Strapping pins

For Sensors (I2C)

• Fixed: D21 (SDA), D22 (SCL)
• Don't change these

For Analog Sensors

• Best: D32, D33, D34, D35, D36, D39
• Note: Last 4 are input-only

For PWM (Motor, Servo)

• Best: D2, D4, D5, D14, D15, D32, D33, D27
• Note: All pins support PWM

For SPI Communication

• Fixed: D18, D19, D23 (+ CS pin)
• Don't change these

---

Troubleshooting Pin Problems

Problem	Cause	Solution
Code won't upload	Strapping pin shorted	Remove wires, upload, reconnect
GPIO doesn't work	Using input-only pin	Switch to D0-D5, D14-D27, D32-D33
Analog reading wrong	Not using ADC pin	Use D32, D33, D34-D36, D39
WiFi stops working	Pin conflict	Check if using GPIO used by WiFi
LED too bright	Current limiting	Add 220Ω resistor

---

Quick Pin Reference Table

SAFE TO USE:          AVOID:
D0  ✓                 D6-D11  ✗ (Flash)
D2  ⚠ (Strapping)     D37-D38 ✗ (JTAG)
D4  ✓                 5V      ✗ (Logic only)
D5  ⚠ (Strapping)
D14 ✓
D15 ✓
D16 ✓ (I2C)
D17 ✓ (I2C)
D18 ✓ (SPI)
D19 ✓ (SPI)
D21 ✓ (I2C)
D22 ✓ (I2C)
D23 ✓ (SPI)
D25 ✓ (DAC)
D26 ✓ (DAC)
D27 ✓
D32-36 ✓ (ADC)
D39 ✓ (ADC input)
GND ✓ (Ground)
3V3 ✓ (Power)

---

Best Practices

1. Always use a GPIO pinout diagram while wiring
2. Double-check pin numbers before connecting
3. Use resistors for LEDs (220Ω minimum)
4. Use pull-up resistors for buttons (10kΩ)
5. Check voltage before connecting sensors
6. Never exceed current limits per pin
7. Use breadboard for testing (no soldering)
8. Add bypass capacitors near power pins (0.1μF)

---

FAQ

Q: Can I use D6-D11? A: No. These are connected to flash memory and will corrupt your program.

Q: Why is my WiFi weak? A: D19 and D18 are used by WiFi. Don't use them for other things.

Q: Can I power an LED directly from a GPIO pin? A: Maybe, but add a resistor (220Ω) to protect the pin.

Q: What's the difference between GPIO and ADC pins? A: GPIO reads digital (HIGH/LOW), ADC reads analog (0-4095).

Q: Can I use multiple I2C sensors? A: Yes! Same pins (D21, D22) with different I2C addresses.

---

Summary

You now know:

✓ Complete ESP32 pinout diagram ✓ What each pin type does ✓ Which pins are safe to use ✓ Which pins to avoid ✓ Real wiring examples ✓ Pin specifications and limits

Save this guide! Bookmark it for every project.

---

Related Guides

• ESP32 WiFi Setup
• ESP32 Analog Reading
• ESP32 I2C Communication
• ESP32 SPI Communication
• ESP32 PWM Control

Last Updated: June 2026 Verified: ESP32 Dev Module