Xilinx Associate Partner

INGESPACE participation in the LEON SVF project

by S. REILLER, ASTRIUM Technical manager
and F. PASQUIER, ASTRIUM study manager




INTRODUCTION LEON SVF PROJECT

With the LEON2-FT processor being released for industrial applications, ESA/ESTEC has initiated and granted to ASTRIUM Satellites a study for the development of a versatile Software Validation Facility (SVF) for this new target processor. By versatile it is meant that this SVF can be configured either as a full software simulation tool or with an hardware accelerator board running the LEON2-FT VHDL code. The LEON2-FT processor is available in VHDL which enables to use commercial off-the-shelf FPGA boards, ease the design of the interface between the CPU and the remaining part of the simulation, while ensuring fidelity.
The hardware accelerator board is an FPGA board in which a XILINX contains the LEON2-FT processor and a support control logic. This VHDL glue enables the simulation software which run on a host PC to control the LEON2-FT processor through PCI. It provides all the required services to the simulation software to simulate all the resources of a full LEON2-FT based On Board Computer (i.e. 1553 buses, SpaceWire link, Real Time Clock…) such as the SRT management, the suspend/resume mechanism, the timed event management and IO access detection… One of the main objective of the study is to develop a LEON2-FT running at 100 MHz with small performance degradation for the simulation of the OBC resources.

STATUS OF THE STUDY BEFORE INGESPACE ARRIVAL

Astrium Satellites has developed and successfully integrated a LEON2-FT processor on a Virtex-4 based FPGA board for a LEON2-FT at 66 MHz. In order to increase the frequency, an improvement proposed by ASTRIUM Satellites and accepted by ESA/ESTEC has been started in june 2008 : the replacement of the FPGA board with another one from the same manufacturer shipped with a more powerful XILINX : the VIRTEX-5.
With this new board, Astrium Satellites generates a LEON2-FT at 90 MHz with an instability issue : the FPGA board was spuriously locked and the only way to unlock the board was to reset the PC ! To fix the instability issue and to increase the frequency of the LEON2-FT, INGESPACE expertise has been requested.

INGESPACE EXPERTISE

Ingespace expertise has been done in two steps. First of all, INGESPACE has reviewed the existing VHDL source code and architecture and tools environment. Then, they have provided a set of recommendations which have been successfully implemented in collaboration with Astrium Satellites team leading to a LEON2-FT at 90 MHz without instability issue.
In addition INGESPACE has proposed a re-design of the VHDL in order to reach the targeted frequency of 100 MHz and to increase the maintainability of the VHDL thanks to a modular architecture. The challenge was to implement exactly the same functionalities in order to avoid any change in the simulation software.
The re-design has been successfully performed by INGESPACE with a modular and incremental approach and tested by Astrium Satellites team on the FPGA board. The hardware accelerator in its new version, is able to run a LEON2-FT at 100 MHz without instability issue. Both teams have worked together in full confidence : INGESPACE for the development and Astrium for the validation and non-regression. These outstanding results have been possible thanks to the actual skills of INGESPACE in VHDL and FPGA tools environment. In addition to these technical skills, INGESPACE has showed a very strong implication in the project which schedule was very tight.