My book «Hands-On Internet of Things with MQTT» (Packt Publishing, 2019) gives an introduction to building connected physical prototypes using the lightweight MQTT protocol.

MQTT is a wonderful pub-sub protocol, which makes it easy to build IoT devices that communicate with each other.

This book is for readers with some Arduino experience who want to learn more about connected devices.

Three hands-on projects teach the reader how to build a physical time-tracking device, an automatic pet-feeder, and an e-ink reminder device.

You can buy the book on the Pack Publishing website, Amazon or O’Reilly.