Control unit
I chose a Raspberry Pi 3 as the control unit of the system, for which I compiled an embedded distribution based on Linux according to my requirements using the buildroot tool. Thanks to this, the whole system takes only a few megabytes.
Modules
I designed and built wireless modules (including PCB design and etching) based on STM32 chips and RFM69 transceivers. I also created the code in C using the STM32CubeMX tool.
App
The application was programmed using the Qt framework. The backend was solved in C++, unlike previous projects. Communication with the control unit was done using SSL sockets. The application was dynamic. After startup, a list of given modules was loaded in the control unit and then the user could see the data about the module. These were sensor value, battery status, and last update times. Finally, a graph was plotted with the values (the plotting was really fast thanks to C++).
