Accurate Time Synchronization in a low-cost platform for the Design of a Distributed Digital Events Detector.

The use of the Internet of Things (IoT) paradigm in various application contexts in recent years has increased the amount of information that can be collected from the field. This has been made possible by the widespread availability of low-cost microcontroller platforms, which ensures their widespread adoption. One of the primary functions of these IoT systems is to identify and, if necessary, time-referred digital events. Design systems that can accurately time-stamp digital events on low-cost platforms can be difficult. This article proposes an architecture that can timestamp external digital signals in UTC by appropriately utilizing peripherals available in low-cost microcontroller platforms and the use of Zephyr Real-Time Operating System (RTOS). The system has been evaluated experimentally on an ESP32 platform. The experimental characterization demonstrated how the proposed method can time stamp an event with a maximum error of 66 ns, in the worst case, while using an 80 MHz reference clock.