August 9, 2016

On-board management unit (UGB)

on-board management unit

© EREMS

EREMS is responsible for the UGB.
The UGB computer has been designed to perform the following hardware functions:

Power supply management provided by the PDU (28V) and mainly:

ON/OFF of the PHARAO equipment
Thermal regulation (heaters and peltiers coolers)

Data handling protocol with the ACES XPLC computer using serial link (time tagging and synchronization with ACES),
Data handling protocols with the PHARAO equipment,
Control the on-board timing and synchronization (micro sequencer),
TM/TC activities to control analogue housekeeping TMs and digital parameters.

The UGB overall dimensions are: 240 x 245 x 120 mm (7.3 l). The unit weight is near 5kg and the total power consumption is less than 30W. The computer is based onto five boards connected to a back frame

CPU board
Digital sampling board
Analogue acquisition board
Power heater board
DC/DC converter boards

Flight Software

The context of the PHARAO project implies two constraints to the flight software, i.e. flexibility and ability to evolve.
Therefore, the main aspect of the PHARAO Flight Software is the definition of a software interpreter. The PHARAO flight software relies on two concepts: an interpreter and scientific sequences.

The Flight Software is constituted of three levels of software:

Board Support Package: this is the first level of software which is in charge of control and supervises the hardware.
Low Level Software: this is the part of the software which provides a set of primitives to operate the hardware and sub-systems.
PHARAO Flight Software: this is the part of the software which implements the functional part (TM/TC management, sub-system control and supervision, interpreter and sequences, etc.) using LBN services. It relies on the software interpreter and scientific sequences. A sequence is a set of software instructions that the flight software has to execute. The sequences are defined by the scientists and the system team. They control and supervise the sub-systems and create TM packages.