GRBOOT is a flight system software suite targeting LEON based systems. The purpose of the boot SW is to provide initialization, self-test and application loading functionality to payload and on-board computers.
GRBOOT is an implementation of the ESA requirements document SAVOIR Flight Computer Initialisation Sequence (SAVOIR-GS-002). The software is developed in accordance with European Space Agency software engineering standards ECSS-E-ST-40C and ECSS-Q-ST-80C, software criticality category B.
GRBOOT is divided into four main parts; initialization, self-tests, standby extension point and application loader. The application loader selects one out of two application images to load, verify and start with optional one of the images as fall back. An interface is provided for users to integrate a custom standby application for low-level maintenance operations before the application loader is executed.
Currently GR740 and GR712RC devices are supported and the SW architecture allows additional systems to be added. System specific components are configured and built based on chip, board and mission configuration.
Ports are available for the GR-CPCI-GR740 and GR712RC development boards, and UT700. Boot memory options include parallel PROM, flash and similar. Application images can be loaded from memory mapped memory (PROM, FLASH, MRAM, etc) or from SPI flash memory. Several main memory options are possible.
Standby extension point
GRBOOT has been prepared with an extension point to allow users to implement a custom maintenance mode (Standby Mode). When the extension point has finished its execution, it can return and engage the application loader. A freestanding minimal C run-time environment is available for the extension.
SpaceWire/PUS Standby extension for GRBOOT
Test and validation
This SW is based on the GR712RC Boot SW which originally was designed specifically for the ESA JUICE mission instruments. The Boot SW has been successfully designed into 8 LEON3FT based instruments on boards the JUICE satellite targeted to launch 2022. The Boot SW have since been adapted to support multiple HW platforms, such as the GR740, and isolating device/mission specific details have made it possible to create a reusable product GRBOOT.