I recently purchased three ESP8266 ESP-05 WiFi modules. These are very cheap WiFi modules costing around $4 USD each, so are ideal for hobbyists, makers and hackers to use in various projects. My idea was to try to get an Arduino web server working on WiFi as a cheap alternative to using an Ethernet shield or WiFi shield.
Although the same module is available from several suppliers, the particular module that I bought was from SainSmart: SainSmart Neu ESP8266 Esp-05 Remote Serial Port WIFI Transceiver Wireless Module AP+STA
ESP8266 ESP-05 Pinout and Documentation
The supplier web page for the ESP8266 ESP-05 had no pinout for the module and no documentation. Some of the information on the web page for the module was also completely wrong, for example they state that the module has 5V compatible I/O, however this is wrong. The I/O pins only work with 3.3V logic and are not 5V tolerant.
They also state “on board antennae”, but this module does not have an on board antennae, it has a connector for an external antennae.
ESP8266 ESP-05 Pinout
After some searching on the web I found a pinout diagram for the 5 pin version of the ESP8266 ESP-05. A new article with pinout and power requirements for the ESP-05 is now available on the Starting Electronics website.
The manufacturer of the ESP8266EX chip found on the ESP-05 and other modules is the Espressif company. Documentation for the module must be taken from the ESP8266EX datasheets on the Espressif website. Look under Documentation on the ESP8266 resource page where you will find datasheets, user guides, application notes, technical references, etc.
Getting Started with the ESP8266 ESP-05 WiFi Module
You bought a ESP8266 5-pin ESP-05 module, now what? Here are the steps necessary to get the module working for the first time. Once you have a basic understanding of the module and where to find further information you will be able to start your own project development.
Soldering the Header
The module comes with a separate 5-pin header that must be soldered into the module. After the header is soldered to the module it is easy to use the module in a breadboard.
The following video shows how to solder the header to the module.
Aerial / Antennae
I found that the module works fine without an aerial / antennae as long as it is near enough to the WiFi router that it is connecting to. Connecting a wire to the aerial connector does give it more range and picks up the second WiFi router that I have on the other side of the house.
Testing the Module
Use the pinout diagram to correctly connect the ESP8266 module power and UART data pins. An Arduino Due is ideal for testing the module. This is because a Due can supply enough current from its 3.3V pin and works with 3.3V logic. The Arduino Due is therefore completely compatible with the ESP8266 module.
The article on testing the ESP8266 ESP-05 module using an Arduino Due shows how to connect the ESP8266 module to the Due and test it. Use this article to get started with sending AT commands to the WiFi module.
Documentation and Staring your Own Projects
Once you have the ESP8266 module working, it is a matter of sending the correct AT commands to the module to set it up for your project.
Find example AT commands in the ESP8266 AT Command Examples document.
Find all of the AT commands in the ESP8266 Instruction Set document.