So as we move to the modern day we are talking more about wireless systems, wireless communication and everything that operates and connects the internet. ESP8266 is a great WiFi module for IoT and Home Automation Projects. Lets dive deeper in this development board.

Introduction

The ESP8266 is a low cost module and it is great for the functions it does at this low price. There are many ways to use the ESP8266, we can program it using the Arduino IDE too. This device will help you build wireless projects from your basic arduino projects.

Functions

This WiFi Module can create :

• Web Servers
• Send Hypertext requests
• Control actuators
• Read Sensors
• Send Email

This list can go on, but we need to get learning this device. Getting started might be a bit tricky, but once you get a hang if it, you will explore another world of wireless modules.

About ESP8266

There are various versions of the ESP8266. The most popular to todays date is ESP-02 and NodeMCU kit.

Pin Diagram NodeMCU

Installing ESP8266 Board for Arduino IDE

So we will be programming the ESP8266 with the Arduino IDE. The best part is that you do not need to learn a new language for programming the ESP8266.

Now for Windows, Linux and Mac OS you can download all the latest Arduino IDE from https://www.arduino.cc/en/Main/Software

After you complete the installation of the IDE. Follow the below instructions:

1. Open the Arduino IDE
2. Click on File —> Preferences
3. Enter the link http://arduino.esp8266.com/stable/package_esp8266com_index.json in the Additional Board Managers URL

4. Open the Boards Manager. Go to Tools > Board > Boards Manager
5. Search for ESP8266 and press install button

Now you have configured the Arduino IDE for the ESP8266. Please note that in order to program Arduino you will have to restore the settings in the board manger and select Arduino Uno or whichever family of Arduino that you use.

Pin Functions / How to use the multipurpose pins

17 GPIO pins are available on the ESP8266, some of the GPIOs have very specific functions and some are advisable not to use. Find the listing to check for the best pins for your project. So just a suggestion, Get your blueprint ready for your innovative project before you can start programming the ESP8266. This process will save hours of your life.

Label on the ESP8266	GPIO	Input	Output	Important Notes
D0	GPIO16	no interrupt	no PWM or I2C support	HIGH at boot used to wake up from deep sleep
D1	GPIO5	OK	OK	SCL
D2	GPIO4	OK	OK	SDA
D3	GPIO0	pulled up	OK	HIGH at boot connected to FLASH button, boot fails if pulled LOW
D4	GPIO2	pulled down	OK	HIGH at boot connected to on-board LED, boot fails if pulled LOW
D5	GPIO14	OK	OK	SPI (SCLK)
D6	GPIO12	OK	OK	SPI (MISO)
D7	GPIO13	OK	OK	SPI (CS) Boot fails if pulled HIGH
D8	GPIO15	pulled to GND	OK	SPI (CS) Boot fails if pulled HIGH
RX	GPIO3	OK	RX	HIGH at boot
TX	GPIO1	TX	OK	debug output at boot, boot fails if pulled LOW
A0	ADC0	Analog Input	X

GPIOs – Flash Chip

GPIO6 to GPIO11 are connected to the flash chip in the ESP8266. These pins are not recommended for use. You can use them based on the notes. As long as they in do not interfere with your requirements.

Pin Status on Boot

The ESP8266 can be prevented from booting if some pins are pulled LOW or HIGH. The following list shows the state of the following pins on BOOT:

• GPIO16: pin is high at BOOT
• GPIO0: boot failure if pulled LOW
• GPIO2: pin is high on BOOT, boot failure if pulled LOW
• GPIO15: boot failure if pulled HIGH
• GPIO3: pin is high at BOOT
• GPIO1: pin is high at BOOT, boot failure if pulled LOW
• GPIO10: pin is high at BOOT
• GPIO9: pin is high at BOOT

There are certain pins that output a 3.3V signal when the ESP8266 boots. This may be problematic if you have relays or other peripherals connected to those GPIOs. All the pins marked in yellow are HIGH.

GPIO4 and GPIO5 are the most safe to use GPIOs if you want to operate relays.

So these are a few notes you may keep in mind before we start programming. We will start with our first program in the next chapter. The other important notes will follow as we program the ESP8266.