ESP8266EX

The ESP8266EX (Figure 1.1) is a single-chip microcontroller developed by Espressif (https://espressif.com/). It can be used to develop low-power, highly-integrated Wi-Fi solutions especially for mobile devices, wearable electronics, and the Internet of Things (IoT) applications. The main advantage of ESP8266EX is that it can give any microcontroller access to a Wi-Fi network. As an example, it can offload all Wi-Fi networking functions for Arduino just like the Arduino Wi-Fi shield:

Figure 1.1: ESP8266EX chip

The chip has the following great features:

Small size (5 mm x 5 mm)
Requires minimal external circuitry
Wide temperature range (-40°C to + 125°C)
All-in-one small package -SoC (integrates a 32-bit Tensilica MCU, standard digital peripheral interfaces, antenna switches, RF balun, power amplifier, low-noise receive amplifier, filters, and power management modules)
Low power consumption

ESP-01

ESP-01 is a small Wi-Fi module based on Espressif ESP8266EX that can give any microcontroller access to a Wi-Fi network. The ESP-01 module (Figure 1.2) is the basic and the most popular board of the ESP8266 module family. You should have an ESP8266 ESP-01 module to understand the basics of ESP8266 and build robotics projects.

This is a list of vendors that typically stock the ESP-01 modules:

SparkFun Electronics: https://www.sparkfun.com/products/13678
Adafruit Industries: https://www.adafruit.com/product/2282
Electrodragon: http://www.electrodragon.com/product/esp8266-wi07c-wifi-module/

Figure 1.2: The original ESP8266 ESP-01. Image courtesy of SparkFun Electronics (https://www.sparkfun.com)

The original ESP8266 ESP-01 has the following features:

Offloads all Wi-Fi networking functions from another application's processor
Self-hosting of applications
Only four pins interface, VCC-3V3, GND, TX, and RX
1 MB (8 MB) flash memory
Pre-programmed AT command set firmware
Supports APSD for VoIP applications and Bluetooth co-existence interfaces

Here is a list of all the ESP8266 boards of the ESP8266 module family at the time of writing:

ESP-01
ESP-02
ESP-03
ESP-04
ESP-05
ESP-06
ESP-07
ESP-08
ESP-09
ESP-10
ESP-11
ESP-12
ESP-12F
ESP-12-E/Q
ESP-12S
ESP-13
ESP-14

Board features and connections

The top of the ESP-01 board consist of the following things:

An ESP8266EX chip—Offloading all Wi-Fi networking functions
A Berg Micro BG25Q80A 1518 flash chip—Serial Peripheral Interface (SPI) flash memory
A printed Wi-Fi antenna—Transmitting and receiving Wi-Fi signals

Figure 1.3: ESP-01 top view

Connections

The original ESP8266 ESP-01 board has eight pins and comes without headers. You can solder regular wires with pins, but if you want to use it with a breadboard, you should attach headers: