  Stratospheric balloons have emerged as an affordable and flexible alternative
to traditional spacecrafts as they are implemented using commercial
off-the-shelf (COTS) equipment without following strict methodologies.
HERCCULES is a stratospheric balloon mission that aims to characterize the
convective heat and radiative environment in the stratosphere. The purpose of
this article is to present the HERCCULES onboard software (OBSW) whose design
and complexity is comparable to that of satellite systems, since it must
control about sixty COTS equipment using a single Raspberry Pi 4B as onboard
computer and ensure the real-time requirements. Compared to similar systems,
novel contributions are presented as the OBSW is developed following modelbased
and component-based approaches using the TASTE toolchain from the European
Space Agency (ESA) for automatic code generation. Besides, the OBSW is verified
and validated following the ESA standards and the results obtained demonstrate
the suitability and efficiency of the solution and the selected methodologies.
