This article details the creation of a toolkit for building a macropad using an Android app and a Linux server, focusing on communication protocols, security considerations, and the challenges of building a complex interface with App Inventor.
An open-source device, kv4p HT, connects to an Android smartphone and turns it into a radio transceiver for about $35. It uses an ESP32 and transmits one watt, featuring APRS and scanning capabilities. The PCB is simple and affordable with a 3D-printed case.
