GPIO Pins of ESP32 | ESP32 Pinout

20th December 2019| 10th March 2025 1 Comment Esp32 3 min read

ESP32 and ESP8266 are two of the most popular development boards, especially for IoT projects. Both are cost-effective Wi-Fi modules perfect for DIY electronics. These boards are equipped with GPIOs, support for protocols like SPI, I2C, UART, and more. What makes them stand out from traditional microcontrollers like Arduino is their built-in wireless networking capabilities, enabling remote control and monitoring via Wi-Fi at a minimal cost.

ESP32 Chip Specifications

The ESP32 is dual-core, meaning it has two processors.
It features built-in Wi-Fi and Bluetooth capabilities.
Runs 32-bit programs with a clock frequency up to 240MHz.
Offers 512 kB RAM and typically comes with 36 GPIO pins.
Includes a variety of peripherals such as capacitive touch, ADCs, DACs, UART, SPI, I2C, and more.
Comes with built-in hall effect and temperature sensors.

ESP32 vs ESP8266 Comparison

Feature	ESP8266	ESP32
MCU	Xtensa Single-core 32-bit L106	Xtensa Dual-Core 32-bit LX6 (600 DMIPS)
Wi-Fi	802.11 b/g/n (HT20)	802.11 b/g/n (HT40)
Bluetooth	X	Bluetooth 4.2 and BLE
Typical Frequency	80 MHz	160 MHz
SRAM	X	✓
Flash	X	✓
GPIO	17	36
Hardware/Software PWM	None / 8 channels	None / 16 channels
SPI/I2C/I2S/UART	2/1/2/2	4/2/2/2
ADC	10-bit	12-bit
CAN	X	✓
Ethernet MAC Interface	X	✓
Touch Sensor	X	✓
Temperature Sensor	X	✓
Hall Effect Sensor	X	✓
Working Temperature	-40ºC to 125ºC	-40ºC to 125ºC

ESP32 GPIO Pinout Overview

ESP32 boards come with 36 GPIO pins that are versatile and configurable for various functionalities such as digital input/output, analog input, touch sensing, and PWM control.

Key Features of ESP32 GPIOs

Configurable as input or output: Each GPIO can be set as an input or output pin with software control.
Analog Support: The ESP32 has 18 ADC channels (12-bit resolution) for analog input.
Capacitive Touch Sensors: 10 dedicated GPIOs are designed for touch sensing.
PWM (Pulse Width Modulation): All GPIOs can be configured as PWM output.
Interrupt Support: Most GPIOs support interrupt capabilities, suitable for handling real-time events.
I2C, SPI, UART Support: GPIOs can be configured for various communication protocols.
Deep Sleep Wake-Up: Select GPIOs can act as wake-up sources when the ESP32 is in deep sleep mode.

ESP32 GPIO Pinout Diagram

Here’s a general pin mapping of the ESP32’s GPIO pins and their functions:

GPIO Pin	Function	Notes
GPIO0	Boot Mode Select	Must be pulled HIGH during boot
GPIO1 (TX)	UART0 TX	Serial communication transmit pin
GPIO2	Built-in LED	Often connected to an onboard LED
GPIO3 (RX)	UART0 RX	Serial communication receive pin
GPIO4	PWM, ADC, Touch	Multipurpose pin
GPIO5	SPI CS	Chip select for SPI interface
GPIO12	ADC, Touch	Often used for touch input
GPIO13	ADC, Touch	Another touch-capable GPIO
GPIO14	PWM, SPI, I2C	Multipurpose pin
GPIO15	PWM, Touch	Multipurpose pin
GPIO32-39	ADC (Analog Inputs)	Supports analog reading

Important Notes on GPIO Usage

GPIO34 to GPIO39 are input-only pins and cannot be used for output functions.
GPIO6 to GPIO11 are connected to the ESP32’s internal flash memory and should be avoided for general use.
Use pull-up or pull-down resistors when necessary to stabilize GPIO behavior.

Best Practices for Using ESP32 GPIOs

Power Considerations: Ensure you follow the voltage limits (3.3V) to avoid damaging the pins.
Pin Mapping: Different ESP32 boards may assign GPIOs to different functions. Always verify the pin mapping for your specific board.
Use External Components: For sensitive sensors, use capacitors or resistors to improve stability.

The ESP32 is a powerful and versatile board packed with features suitable for both beginners and experienced developers. Its advanced GPIO capabilities, combined with Wi-Fi and Bluetooth connectivity, make it an excellent choice for IoT, robotics, and home automation projects.