The Internet of Things has revolutionized the way we interact with the physical world mainly because of the ease of data exchange which we can make almost everywhere. IoT relies on exchanging information between a myriad of devices and sensors, all of which need to communicate with each other and often with the cloud or other servers. The most exciting Internet of Things features are the possibility of using data transmission between nodes, between nodes and servers, and the ability to read measurements and control the behaviour of devices remotely. All these features use networking functionality. IoT networking is the backbone of the IoT ecosystem, enabling devices to collect and transmit data, receive instructions, and interact with other devices, even from another part of the World.
In the previous chapters, some examples were presented for sensors, actuators and other interesting elements, but without the use of computer networks. This chapter presents some elementary programming examples for networking with the use of Espressif SoCs as the Edge-class devices, and Raspberry PI as the Fog-class device. Espressif SoCs can be used as WiFi network controllers connected to other microcontrollers (e.g. Arduino Uno), and programmed with a set of “AT” commands. They can also be stand-alone microcontrollers with on-board network capabilities. ESP8266 and ESP32 can use Wi-Fi connectivity while many versions of ESP32 can also use Bluetooth. In WiFi networks, the Espressif chips can operate as the network client (like a normal computer connected to the Access Point or Router), as the network provider (Access Point), or in both modes simultaneously (as the Repeater).
In this chapter, the emphasis will be put on the ESP8266 SoC, and all the examples will present software for this chip.