OpenWater Hub: An open-source hardware platform for marine robotics support and water quality data acquisition

Marine environmental research often suffers from hardware fragmentation, requiring separate, incompatible systems for laboratory testing, portable field analysis, and long-term offshore monitoring. This increases costs and complicates data integration. This paper presents the OpenWater Hub, a versatile, open- source hardware platform that merges these functions into a single, reconfigurable electronics board. The system is built on a dual-microcontroller architecture (ATmega128A) that handles both high-speed sensor polling via industrial RS485 protocols and direct actuator control through high-current PWM channels. This paper details three specific builds using the same core: (1) a standalone data logger for benchtop calibration, (2) a portable field kit for rapid in-situ water quality monitoring and analysis, and (3) an autonomous floating station that serves as both a long- term environmental monitor and a power/communication gateway for tethered underwater robots. Tests showed the system’s ability to interface with multiple industrial sensors, maintain stable long- range LoRa telemetry, and provide direct open-loop control for soft robotic platforms. The complete design files, firmware, and build instructions are provided to facilitate reproducible marine research.