There's an excellent book (and associated open source project) on using state machines for reactive systems or embedded systems in general: "Practical UML State

There's an excellent book (and associated open source project) on using state machines for reactive systems or embedded systems in general: "Practical UML Statecharts in C/C++, 2nd Edition: Event-Driven Programming for Embedded Systems" by Miro Samek. Here's a link to the site where you can download it from (https://www.state-machine.com/psicc2 https://www.state-machine.com/psicc2).