In this article by Marco Schwartz the authors of the book ESP8266 Internet of Things Cookbook, we will learn following recipes:

• Setting up the Arduino development environment for the ESP8266
• Choosing an ESP8266
• Required additional components

(For more resources related to this topic, see here.)

Setting up the Arduino development environment for the ESP8266

To start us off, we will look at how to set up Arduino IDE development environment so that we can use it to program the ESP8266. This will involve installing the Arduino IDE and getting the board definitions for our ESP8266 module.

Getting ready

The first thing you should do is download the Arduino IDE if you do not already have it installed in your computer. You can do that from this link:

https://www.arduino.cc/en/Main/Software.

The webpage will appear as shown. It features that latest version of the Arduino IDE. Select your operating system and download the latest version that is available when you access the link (it was 1.6.13 at when this articlewas being written):

When the download is complete, install the Arduino IDE and run it on your computer.

Now that the installation is complete it is time to get the ESP8266 definitions. Open the preference window in the Arduino IDE from File|Preferences or by pressing CTRL+Comma.

Copy this URL: http://arduino.esp8266.com/stable/package_esp8266com_index.json.

Paste it in the filed labelled additional board manager URLs as shown in the figure. If you are adding other URLs too, use a comma to separate them:

Open the board manager from the Tools|Board menu and install the ESP8266 platform. The board manager will download the board definition files from the link provided in the preferences window and install them. When the installation is complete the ESP8266 board definitions should appear as shown in the screenshot. Now you can select your ESP8266 board from Tools|Board menu:

How it works…

The Arduino IDE is an open source development environment used for programming Arduino boards and Arduino-based boards. It is also used to upload sketches to other open source boards, such as the ESP8266. This makes it an important accessory when creating Internet of Things projects.

Choosing an ESP8266 board

The ESP8266 module is a self-contained System On Chip (SOC) that features an integrated TCP/IP protocol stack that allows you to add Wi-Fi capability to your projects. The module is usually mounted on circuit boards that breakout the pins of the ESP8266 chip, making it easy for you program the chip and to interface with input and output devices.

ESP8266 boards come in different forms depending on the company that manufactures them. All the boards use Espressif’s ESP8266 chip as the main controller, but have different additional components and different pin configurations, giving each board unique additional features.

Therefore, before embarking on your IoT project, take some time to compare and contrast the different types of ESP8266 boards that are available. This way, you will be able to select the board that has features best suited for your project.

Available options

The simple ESP8266-01 module is the most basic ESP8266 board available in the market. It has 8 pins which include 4 General Purpose Input/Output (GPIO) pins, serial communication TX and RX pins, enable pin and power pins VCC and GND. Since it only has 4 GPIO pins, you can only connect three inputs or outputsto it.

The 8-pin header on the ESP8266-01 module has a 2.0mm spacing which is not compatible with breadboards. Therefore, you have to look for another way to connect the ESP8266-01 module to your setup when prototyping. You can use female to male jumper wires to do that:

The ESP8266-07 is an improved version of the ESP8266-01 module. It has 16 pins which comprise of 9 GPIO pins, serial communication TX and RX pins, a reset pin, an enable pin and power pins VCC and GND. One of the GPIO pins can be used as an analog input pin.The board also comes with a U.F.L. connector that you can use to plug an external antenna in case you need to boost Wi-Fi signal.

Since the ESP8266 has more GPIO pins you can have more inputs and outputs in your project. Moreover, it supports both SPI and I2C interfaces which can come in handy if you want to use sensors or actuators that communicate using any of those protocols. Programming the board requires the use of an external FTDI breakout board based on USB to serial converters such as the FT232RL chip.

The pads/pinholes of the ESP8266-07 have a 2.0mm spacing which is not breadboard friendly. To solve this, you have to acquire a plate holder that breaks out the ESP8266-07 pins to a breadboard compatible pin configuration, with 2.54mm spacing between the pins. This will make prototyping easier.

This board has to be powered from a 3.3V which is the operating voltage for the ESP8266 chip:

The Olimex ESP8266 module is a breadboard compatible board that features the ESP8266 chip. Just like the ESP8266-07 board, it has SPI, I2C, serial UART and GPIO interface pins. In addition to that it also comes with Secure Digital Input/Output (SDIO) interface which is ideal for communication with an SD card. This adds 6 extra pins to the configuration bringing the total to 22 pins.

Since the board does not have an on-board USB to serial converter, you have to program it using an FTDI breakout board or a similar USB to serial board/cable. Moreover it has to be powered from a 3.3V source which is the recommended voltage for the ESP8266 chip:

The Sparkfun ESP8266 Thing is a development board for the ESP8266 Wi-Fi SOC. It has 20 pins that are breadboard friendly, which makes prototyping easy. It features SPI, I2C, serial UART and GPIO interface pins enabling it to be interfaced with many input and output devices.There are 8 GPIO pins including the I2C interface pins.

The board has a 3.3V voltage regulator which allows it to be powered from sources that provide more than 3.3V. It can be powered using a micro USB cable or Li-Po battery. The USB cable also charges the attached Li-Po battery, thanks to the Li-Po battery charging circuit on the board.

Programming has to be done via an external FTDI board:

The Adafruit feather Huzzah ESP8266 is a fully stand-alone ESP8266 board. It has built in USB to serial interface that eliminates the need for using an external FTDI breakout board to program it. Moreover, it has an integrated battery charging circuit that charges any connected Li-Po battery when the USB cable is connected. There is also a 3.3V voltage regulator on the board that allows the board to be powered with more than 3.3V.

Though there are 28 breadboard friendly pins on the board, only 22 are useable. 10 of those pins are GPIO pins and can also be used for SPI as well as I2C interfacing. One of the GPIO pins is an analog pin:

What to choose?

All the ESP8266 boards will add Wi-Fi connectivity to your project. However, some of them lack important features and are difficult to work with. So, the best option would be to use the module that has the most features and is easy to work with. The Adafruit ESP8266 fits the bill.

The Adafruit ESP8266 is completely stand-alone and easy to power, program and configure due to its on-board features. Moreover, it offers many input/output pins that will enable you to add more features to your projects. It is affordable andsmall enough to fit in projects with limited space.

There’s more…

Wi-Fi isn’t the only technology that we can use to connect out projects to the internet. There are other options such as Ethernet and 3G/LTE. There are shields and breakout boards that can be used to add these features to open source projects. You can explore these other options and see which works for you.

Required additional components

To demonstrate how the ESP8266 works we will use some addition components. These components will help us learn how to read sensor inputs and control actuators using the GPIO pins. Through this you can post sensor data to the internet and control actuators from the internet resources such as websites.

Required components

The components we will use include:

• Sensors
• DHT11
• Photocell
• Soil humidity
• Actuators
• Relay
• Powerswitch tail kit
• Water pump
• Breadboard
• Jumper wires
• Micro USB cable

Sensors

Let us discuss the three sensors we will be using.

DHT11

The DHT11 is a digital temperature and humidity sensor. It uses a thermistor and capacitive humidity sensor to monitor the humidity and temperature of the surrounding air and produces a digital signal on the data pin. A digital pin on the ESP8266 can be used to read the data from the sensor data pin:

Photocell

A photocell is a light sensor that changes its resistance depending on the amount of incident light it is exposed to. They can be used in a voltage divider setup to detect the amount of light in the surrounding. In a setup where the photocell is used in the Vcc side of the voltage divider, the output of the voltage divider goes high when the light is bright and low when the light is dim. The output of the voltage divider is connected to an analog input pin and the voltage readings can be read:

Soil humidity sensor

The soil humidity sensor is used for measuring the amount of moisture in soil and other similar materials. It has two large exposed pads that act as a variable resistor. If there is more moisture in the soil the resistance between the pads reduces, leading to higher output signal. The output signal is connected to an analog pin from where its value is read:

Actuators

Let’s discuss about the actuators.

Relays

A relay is a switch that is operated electrically. It uses electromagnetism to switch large loads using small voltages. It comprises of three parts: a coil, spring and contacts. When the coil is energized by a HIGH signal from a digital pin of the ESP8266 it attracts the contacts forcing them closed. This completes the circuit and turns on the connected load. When the signal on the digital pin goes LOW, the coil is no longer energized and the spring pulls the contacts apart. This opens the circuit and turns of the connected load:

Power switch tail kit

A power switch tail kit is a device that is used to control standard wall outlet devices with microcontrollers. It is already packaged to prevent you from having to mess around with high voltage wiring. Using it you can control appliances in your home using the ESP8266:

Water pump

A water pump is used to increase the pressure of fluids in a pipe. It uses a DC motor to rotate a fan and create a vacuum that sucks up the fluid. The sucked fluid is then forced to move by the fan, creating a vacuum again that sucks up the fluid behind it. This in effect moves the fluid from one place to another:

Breadboard

A breadboard is used to temporarily connect components without soldering. This makes it an ideal prototyping accessory that comes in handy when building circuits:

Jumper wires

Jumper wires are flexible wires that are used to connect different parts of a circuit on a breadboard:

Micro USB cable

A micro USB cable will be used to connect the Adafruit ESP8266 board to the compute:

Summary

In this article we have learned how to setting up the Arduino development environment for the ESP8266,choosing an ESP8266, and required additional components. 

Resources for Article:

Further resources on this subject:

• Internet of Things with BeagleBone [article]
• Internet of Things Technologies [article]
• BLE and the Internet of Things [article]