Droopy: A Dynamic Runtime Platform for Micro-Controller Units Supporting Partial and Incremental Updates of Modularized Firmware

Long-range and low-power wireless communication technologies, such as LoRa, Sigfox, myiot and Wi-Fi HaLow, have emerged to massively connect things to the Internet. The ability to effectively update the firmware of these things over the air is becoming a necessity, particularly when resources are restricted. This paper presents Droopy, a runtime platform for things powered by MCUs that supports the deployment and execution of firmware designed as a composition of software modules that can express dependencies on other modules. Droopy currently enables partial and incremental over-the-air updates of modules using LoRaWAN, and does not necessarily require a reboot to apply these updates. Modules can be stored in flash memory, or copied to RAM to speed up execution. This paper outlines an implementation of Droopy on STM32 MCUs and details an evaluation of its performance.