If you are looking for a small yet powerful IoT device, you are likely to come across the ESP8266 and compatible products on the market today. One of these, the Wemos/Lolin D1 Mini Pro board strikes a remarkable balance between cost and performance. A small and very affordable prototype board, the D1 Mini Pro stands out with its WiFi functionality and a 16-Mbytes flash memory for easy creation of a flash file system. In addition, there are sufficient input and output pins (only one analog input though) to support PWM, I²C, and One-Wire systems to mention but a few. The book describes the operation, modding, construction, and programming of home appliances including a colorful smart home accessory, a refrigerator/greenhouse controller, an AC powerline monitor, a door lock monitor, and an IKEA Trådfri controller. As a benefit, all firmware developed for these DIY, IoT-ized devices can be updated over-the-air (OTA). For most of the designs in the book, a small printed circuit board (PCB) and an enclosure are presented so readers can have a finished and attractive-looking product. Readers having - or with access to! - a 3D printer can print the suggested enclosures at home or in a shop. Some of the constructions benefit from a Raspberry Pi configured as a gateway or cms server. This is also described in detail with all the necessary configuring. You dont need to be an expert but the prerequisites to successful replication of the projects include basic skills with PC software including the ability to surf the Internet. In terms of hardware, you should be comfortable with soldering and generally assembling the PCBs presented in the book. All custom software written for the IoT devices, the PCB layouts, and 3D print files described in the book are available for free downloading from www.elektor.com/20370.

Hans Henrik Skovgaard has over 25 years of management experience in the mobile phone industry and holds an MSc. in Electronic Engineering. He has authored four top-selling books on electronics design and embedded software.