Digital PCB Design and Bootloader for ROMEO radiation-tolerant Langmuir Probe Instrument

The digital electronics of a satellite instrument must be able to progress from power-on or reset to application execution without the continuous debugging support available during laboratory development. This thesis addresses this problem for the Langmuir Probe Instrument (LPI) on the Research and Observation in Medium Earth Orbit (ROMEO) satellite, that follows a radiation-aware architecture based on the NanoXplore NG-Medium field-programmable gate array (FPGA) and a LEON3 soft-core processor.
The work combines two connected developments. First, the DataHub+ digital printed circuit board (PCB) was developed to provide the hardware platform required by the NG-Medium/LEON3 system. The design addresses the FPGA voltage domains, memory subsystem, configuration, clock, reset, debug and communication interfaces, together with the placement, routing, manufacturing and signal-integrity constraints of the multilayer PCB. Second, a standalone bare-metal bootloader, referred to as Stage-0, was implemented for the LEON3 processor. Stage-0 validates stored software images using structured headers and cyclic redundancy checks, maintains redundant persistent boot metadata, selects software images according to a defined state and retry policy, loads the selected payload into execution memory, and provides fallback to golden recovery images when required.
Stage-0 was verified on the NG-Medium development platform through controlled fault injection, reset and power-cycle tests. The results confirmed software-image integrity checking, deterministic image selection and fallback, redundant metadata recovery, trial-boot handling, runtime-failure management, recovery from storage-access failures, and autonomous startup to the selected application.
Together, these developments provide a hardware and software foundation for further radiation tolerant Langmuir probe instrument integration. The DataHub+ remains a design-level artifact and was not fabricated or electrically tested, while radiation qualification and integration with the final application based on the Real-Time Executive for Multiprocessor Systems (RTEMS) remain outside the scope of this work.