No doubt, Arduino became the most widespread SoC, particularly among enthusiasts, educators, amateurs, and hobbyists, driving de-facto the embedded systems market for years.

Using cheap Atmel AVR microcontrollers, delivered along with development board and peripherals of almost any kind, including sensors and actuators, where you do not need to develop your PCB nor solder to obtain the fully functional device, all that triggered a new era where almost anyone can afford to have a development set and start playing the way only professionals used to do. Moreover, Arduino was not only the hardware but also the programming idea, delivering a simple development environment that is easy to use for beginners. Perhaps the most important impact of the Arduino on daily use was to spread the idea of taking automation control from the industry and bringing it on a massive scale to regular life, homes, cars, and toys to automate daily life.

The beginnings of the Arduino are dated to the year 2003 in Italy. Their most popular development board was delivered to the market in the fall of 2010. While AVRs microcontrollers are considered to be embedded systems more than IoT, and most of the early Arduino boards didn't offer any network interface, even then, it is essential to understand the idea of how to work with SoCs, so we start our guide here. However, many extension boards are present, suitable for the standard development boards (so-called shields) that offer wired and wireless networking for Arduino. Some of the Arduino development boards nowadays do integrate networking SoC into one board, i.e. Arduino Yun. Also, their clones, mostly made by Chinese manufacturers, evolved into more sophisticated products, integrating, i.e. Arduino Mega 2560 and ESP8266 SoC into one development board.

The following chapters present the Arduino hardware overview, peripherals and programming as universal basics for IoT systems development using advanced processors like ESP:

• “setting_up_programming_environment”;

• “building_your_first_project”;

• “data_types_and_variable”;

• “program_control_structures”;

• “looping”;

• “interrupts_and_sub-programs”;

• “interacting_with_hardware_devices_and_debugging_the_code”.