LEON процессоры: Ғарышқа арналған радиацияға төзімді микропроцессорлар отбасысы

32 bit CPU microprocessor core originally designed by the European Space Agency
the family of microprocessors

LEON (from lang es meaning lion) is a radiation tolerant 32 bit central processing unit (CPU) microprocessor core that implements the SPARC V8 instruction set architecture (ISA) developed by Sun Microsystems. It was originally designed by the European Space Research and Technology Centre (ESTEC), part of the European Space Agency (ESA), without any involvement by Sun. Later versions have been designed by Gaisler Research, under a variety of owners. It is described in synthesizable VHSIC Hardware Description Language (VHDL). LEON has a dual license model: An GNU Lesser General Public License (LGPL) and GNU General Public License (GPL) free and open source software (FOSS) license that can be used without licensing fee, or a proprietary license that can be purchased for integration in a proprietary product. The core is configurable through VHDL generics, and is used in system on a chip (SOC) designs both in research and commercial settings.

The LEON project was begun by the European Space Agency (ESA) in late 1997 to study and develop a high performance processor to be used in European space projects. The objectives for the project were to provide an open, portable and non proprietary processor design, capable to meet future requirements for performance, software compatibility and low system cost. Another objective was to be able to manufacture in a single event upset (SEU) tolerant sensitive semiconductor process. To maintain correct operation in the presence of SEUs, extensive error detection and error handling functions were needed. The goals have been to detect and tolerate one error in any register without software intervention, and to suppress effects from Single Event Transient (SET) errors in combinational logic. The LEON family includes the first LEON1 VHSIC Hardware Description Language (VHDL) design that was used in the LEONExpress test chip developed in 0.25 μm technology to prove the fault tolerance concept. The second LEON2 VHDL design was used in the processor device AT697 from Atmel (F) and various system on chip devices. These two LEON implementations were developed by ESA. Gaisler Research, now part of Cobham (and previously Aeroflex Gaisler), developed the third LEON3 design and has announced the availability of the fourth generation LEON, the LEON4 processor.

Design flow documentation for the LEON into FPGA are available from the manufacturer and from third party resources.

The term LEON2/LEON2 FT often refer to the LEON2 system on chip design, which is the LEON2 processor core together with the standard set of peripherals available in the LEON2( FT) distribution. Later processors in the LEON series are used in a wide range of designs and are therefore not as tightly coupled with a standard set of peripherals. With LEON3 and LEON4 the name typically refers to only the processor core, while LEON/GRLIB is used to refer to the complete system on chip design.

The LEON2 FT processor is the single event upset fault tolerant (FT) version of the LEON2 processor. Flip flops are protected by triple modular redundancy and all internal and external memories are protected by EDAC or parity bits. Special licence restrictions apply to this IP (distributed by the European Space Agency and China's Chang'e 4 lunar lander.

The LEON3 is a synthesisable VHDL model of a 32 bit processor compliant with the SPARC V8 architecture. The model is highly configurable, and particularly suitable for system on a chip (SoC) designs. The full source code is available under the GNU GPL license, allowing use for any purpose without licensing fee. LEON3 is also available under a proprietary license, allowing it to be used in proprietary applications. There are several differences between the two LEON2 processor models and the LEON3. LEON3 includes SMP support and a seven stage pipeline, while LEON2 does not support SMP and has a five stage pipeline.

In January 2010, the fourth version of the LEON processor was released.

The Real time operating systems that support the LEON core are currently RTLinux, PikeOS, eCos, RTEMS, Nucleus, ThreadX, OpenComRTOS, VxWorks (a port by Gaisler Research), LynxOS (also a port by Gaisler Research), POK (a free ARINC653 implementation released under the BSD licence) and ORK+, an open source real time kernel for high integrity real time applications with the Ravenscar Profile, Embox an open source configurable real time OS which allows using Linux software without Linux.