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How Does an ESP32 Board Run and Communicate?

  • Basic
  • Article
  • Ages 15+
  • 4 min read
A compact microcontroller board with a metal shield is wired to a temperature sensor.

The ESP32-DevKitC V4 example in this article is a development board carrying an ESP32-WROOM-32E module, with the ESP32 chip at its core, plus a USB port and pin headers that bring signals out. You load firmware from a computer over the serial port, and the chip can communicate wirelessly over Wi-Fi and Bluetooth. The board can be used to build IoT devices.

Contents
A computer loads a program onto the board, which communicates wirelessly.
  • Computer
  • ESP32 board
  • Wireless link

What you will learn

Before you start

It helps to know what GPIO and UART are.

What parts does an ESP32 board have?

The ESP32-DevKitC is a small development board based on the ESP32, made by Espressif. The V4 comes with several module variants; the documented example uses the ESP32-WROOM-32E, a module with the ESP32 at its core.

Most of the I/O pins on the ESP module are broken out to the pin headers on the board. Developers can either connect peripherals with jumper wires or mount the board on a breadboard. On the V4, avoid using D0, D1, D2, D3, CMD and CLK as peripheral pins: they are used internally for flash memory.

Module in the middle, USB port at one end, pins along the sides.
  • Development board
  • ESP32 module
  • USB port

How is firmware loaded onto the board?

The Micro-USB port supplies power to the board and carries communication between a computer and the module. Holding down Boot and then pressing EN starts Firmware Download mode, which loads firmware through the serial port.

ESP-IDF is the official development framework for the ESP32 series of chips. A simple example shows how to use ESP-IDF for menu configuration, then for building and flashing firmware onto an ESP32 board.

Firmware travels from the computer through USB to the board; Boot and EN switch it to download mode.
  • Computer with ESP-IDF
  • USB cable
  • ESP32 board
  • Symbol for Boot and EN buttons

How does the ESP32 communicate wirelessly?

The ESP32 is a Wi-Fi and Bluetooth combo chip. Depending on the variant, it contains one or two microprocessors.

One chip with two kinds of wireless link.
  • ESP32 chip
  • Wi-Fi
  • Bluetooth

Real-world example

With an adult, think of a temperature sensor that sends readings over the home network. An ESP32 board reads the sensor through its pins, then sends the readings over Wi-Fi.

Common misunderstandings

An ESP32 board and an ESP32 chip are the same. The chip is the core; the development board adds a module, a USB port and pin headers.

Firmware must be loaded over Wi-Fi. The documented ESP32-DevKitC V4 can enter download mode and receive firmware over its serial connection; other update methods depend on the board and firmware.

Frequently asked questions

What is the ESP32?

The ESP32 is Espressif's Wi-Fi and Bluetooth combo chip.

What is ESP-IDF for?

It is the official development framework for building and flashing firmware for the ESP32.

What are the Boot and EN buttons for?

EN is the reset button. Hold Boot and then press EN to enter Firmware Download mode through the serial port.

What does the USB port on the board do?

It supplies power and carries communication between a computer and the module.

Summary

  • An ESP32 board has a module, a USB port and pin headers that bring signals out.
  • Firmware is loaded from a computer through the serial port, with ESP-IDF as the development framework.
  • The ESP32 is a Wi-Fi and Bluetooth combo chip.

Terms in this article

English and Vietnamese terms, with the meanings used here. Hover, tap or Tab to a term with a dotted underline for an explanation as you read.

ESP32
Espressif's Wi-Fi and Bluetooth combo chip, with one or two microprocessors depending on the variant.
Development boardBo phát triển
In the ESP32-DevKitC V4 example, the board breaks out module pins to headers and has a USB port for programming and testing.
Module
A small unit with the ESP32 chip at its core, mounted on the development board.
Firmware
The program loaded onto the board, here through the serial port.
ESP-IDF
Espressif's official development framework for ESP32 chips.

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Sources

These sources are written for older readers. If they feel hard, read them with an adult.