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Design and Implementation of Spacecraft Avionics Software Architecture based on
Spacecraft Onboard Interface Services and Packet Utilization Standard
Beijing Institute of Spacecraft System Engineering, China Academy of Space Technology (CAST)
Xiongwen He
10/11/2015
Catalogue
Introduction1
Software Architecture Design2
Implementation and Verification3
Conclusion4
1. Introduction
Currently the characteristics of integration of functions have occurred in
spacecraft, especially in Chinese spacecraft. Traditional spacecraft
functions such as Telemetry and Telecommand, data handling and so on,
have been integrated into avionics system, which also realizes the
autonomous function, including information management, resource
management, operation management and safety management.
1. Introduction
The benefit of integration is the uniform and optimized configuration of
resources, the reduction of power consumption and weight, the
improvement of autonomous ability and the standardization of interface
and products. However, the coupling of each subsystem is also increased
and the hardware and software are becoming more complicated.
How to make the avionics system software adapt the different hardware
interface, protocols and the change of user requirements, and to increase
the reusability of software, is the problem that is to be solved during the
avionics system software architecture design.
1. Introduction
SOIS is focused on the research of onboard information exchange and the
onboard interface of each subsystem and equipment. The layered
architecture defined by CCSDS can shield the upper layer from the
change of hardware and provide a set of standard services to be used by
user applications. The concept of SOIS can be referenced and adopted in
the design of avionics system software architecture.
ECSS published the Telemetry and Telecommand Packet Utilization
Standard (PUS) , which defined 16 services and standardized the
application layer interface between ground and spacecraft, provided
support for the top-level application of avionics system.
1. Introduction
With SOIS and PUS integrated, a new avionics system software
architecture has been designed to solve the problem mentioned above,
thus increase the software reuse, shorten the software development cycle
and increase the efficiency of software development.
Catalogue
Introduction1
Software Architecture Design2
Implementation and Verification3
Conclusion4
2. Software Architecture Design
2.1 Principles
- decompose and simplify the complex problem into several layers
through layering
- standardize the interface of operating system
- define the framework of device drivers
- establish a uniform information transfer mechanism
- define the standardized components and their interfaces
2. Software Architecture Design
2.2 Software Architecture Design
Based on the principles, we presented a software architecture which
includes operating system layer, middleware layer and application layer.
Hardware
CPU Timer
UART
Watchdog
1553BInner Bus
ROM RAM
Extension Interface
Operating System Layer
Real-time Kernel
BSPDevice Drivers
MTS Compone
nt
DDPS Compon
ent
TAS Compon
ent
FPSS Component
Space Packet Component
Onboard Subnet Components
PUS Service Components
Basic Function Library
System Configu-ration Manage-ment
Application Layer
Thermal Management
Power Management
Time Management
Housekeeping Management
Extension
Application SupportLayer
TransferLayer
Subnetwork Layer
Middleware Layer
Space Subnet Components
Telemetry Telecommand
Operating System API
Middleware API
DAS Compo
nent
DVS Compone
nt
Extension
Extension
Payload Management
2. Software Architecture Design
2.2 Software Architecture Design
( 1 ) Operating System Layer
- provide a uniform API
- any Operating System that supports
this API can be used
- include real-time kernel, BSP, device
drivers and basic function library
- new devices supported by add new
driversHardware
CPU Timer
UART
Watchdog
1553BInner Bus
ROM RAM
Extension Interface
Operating System Layer
Real-time Kernel
BSPDevice Drivers
MTS Compone
nt
DDPS Compon
ent
TAS Compon
ent
FPSS Component
Space Packet Component
Onboard Subnet Components
PUS Service Components
Basic Function Library
System Configu-ration Manage-ment
Application Layer
Thermal Management
Power Management
Time Management
Housekeeping Management
Extension
Application SupportLayer
TransferLayer
Subnetwork Layer
Middleware Layer
Space Subnet Components
Telemetry Telecommand
Operating System API
Middleware API
DAS Compo
nent
DVS Compone
nt
Extension
Extension
Payload Management
2. Software Architecture Design
2.2 Software Architecture Design
( 2 ) Middleware Layer
- a common service platform
- integrate SOIS and PUS
- has standard program interface and
protocols
- is divided into three layers
Hardware
CPU Timer
UART
Watchdog
1553BInner Bus
ROM RAM
Extension Interface
Operating System Layer
Real-time Kernel
BSPDevice Drivers
MTS Compone
nt
DDPS Compon
ent
TAS Compon
ent
FPSS Component
Space Packet Component
Onboard Subnet Components
PUS Service Components
Basic Function Library
System Configu-ration Manage-ment
Application Layer
Thermal Management
Power Management
Time Management
Housekeeping Management
Extension
Application SupportLayer
TransferLayer
Subnetwork Layer
Middleware Layer
Space Subnet Components
Telemetry Telecommand
Operating System API
Middleware API
DAS Compo
nent
DVS Compone
nt
Extension
Extension
Payload Management
2. Software Architecture Design
2.2 Software Architecture Design
( 2 ) Middleware Layer
Subnetwork Layer
- include onboard subnet components
and space subnet components
- support packet service, memory
access service, synchronization
service, link convergence
- support TC protocol, AOS protocol
- isolate the influence of the change of
hardware interface and protocols
Hardware
CPU Timer
UART
Watchdog
1553BInner Bus
ROM RAM
Extension Interface
Operating System Layer
Real-time Kernel
BSPDevice Drivers
MTS Compone
nt
DDPS Compon
ent
TAS Compon
ent
FPSS Component
Space Packet Component
Onboard Subnet Components
PUS Service Components
Basic Function Library
System Configu-ration Manage-ment
Application Layer
Thermal Management
Power Management
Time Management
Housekeeping Management
Extension
Application SupportLayer
TransferLayer
Subnetwork Layer
Middleware Layer
Space Subnet Components
Telemetry Telecommand
Operating System API
Middleware API
DAS Compo
nent
DVS Compone
nt
Extension
Extension
Payload Management
2. Software Architecture Design
2.2 Software Architecture Design
( 2 ) Middleware Layer
Transfer Layer
- include Space packet protocol
component
- space packet protocol is enhanced with
address information added in the
secondary header
- syncretize the space link and onboard
link using packets
Hardware
CPU Timer
UART
Watchdog
1553BInner Bus
ROM RAM
Extension Interface
Operating System Layer
Real-time Kernel
BSPDevice Drivers
MTS Compone
nt
DDPS Compon
ent
TAS Compon
ent
FPSS Component
Space Packet Component
Onboard Subnet Components
PUS Service Components
Basic Function Library
System Configu-ration Manage-ment
Application Layer
Thermal Management
Power Management
Time Management
Housekeeping Management
Extension
Application SupportLayer
TransferLayer
Subnetwork Layer
Middleware Layer
Space Subnet Components
Telemetry Telecommand
Operating System API
Middleware API
DAS Compo
nent
DVS Compone
nt
Extension
Extension
Payload Management
2. Software Architecture Design
2.2 Software Architecture Design
( 2 ) Middleware Layer
Application Support Layer
- support SOIS MTS , DAS , DVS ,DDPS , TAS , FPSS services
- support PUS services
- allow Service Extension
Hardware
CPU Timer
UART
Watchdog
1553BInner Bus
ROM RAM
Extension Interface
Operating System Layer
Real-time Kernel
BSPDevice Drivers
MTS Compone
nt
DDPS Compon
ent
TAS Compon
ent
FPSS Component
Space Packet Component
Onboard Subnet Components
PUS Service Components
Basic Function Library
System Configu-ration Manage-ment
Application Layer
Thermal Management
Power Management
Time Management
Housekeeping Management
Extension
Application SupportLayer
TransferLayer
Subnetwork Layer
Middleware Layer
Space Subnet Components
Telemetry Telecommand
Operating System API
Middleware API
DAS Compo
nent
DVS Compone
nt
Extension
Extension
Payload Management
2. Software Architecture Design
2.2 Software Architecture Design
( 3 ) Application Layer
- contains most of the common
functions of avionics system
- combine the different basic services of
middleware layer to implement
functions
- using tasks or processes with OS
supportHardware
CPU Timer
UART
Watchdog
1553BInner Bus
ROM RAM
Extension Interface
Operating System Layer
Real-time Kernel
BSPDevice Drivers
MTS Compone
nt
DDPS Compon
ent
TAS Compon
ent
FPSS Component
Space Packet Component
Onboard Subnet Components
PUS Service Components
Basic Function Library
System Configu-ration Manage-ment
Application Layer
Thermal Management
Power Management
Time Management
Housekeeping Management
Extension
Application SupportLayer
TransferLayer
Subnetwork Layer
Middleware Layer
Space Subnet Components
Telemetry Telecommand
Operating System API
Middleware API
DAS Compo
nent
DVS Compone
nt
Extension
Extension
Payload Management
2. Software Architecture Design
2.3 Interface Design
( 1 ) Interface of each layer
- Operating system layer interface: includes task management
interface, interrupt management interface, memory management
interface, semaphore management interface, timer management
interface, IO interface, user support library interface and so on.
- Subnetwork layer interface: includes packet service interface,
memory access service interface, synchronization service interface,
TC interface, AOS interface and so on.
- Transfer Layer interface: includes space packet interface and so on.
- Application Support Layer: includes PUS interface, MTS
interface,DAS interface ,…
2. Software Architecture Design
2.3 Interface Design
( 2 ) Interface of Component
The outside interface contains the following types.
- the provided interface, including:
- initialization interface
- functional interface
- configuration interface
- the needed interface: called by this component, which is realized
through configuration.
Catalogue
Introduction1
Software Architecture Design2
Implementation and Verification3
Conclusion4
3. Implementation and Verification
The architecture is implemented and verified based on avionics system
prototype , including SMU and SDIU.
- device drivers and BSP developed
- 28 software components of the middleware developed
- coded more than 40000 lines
- programmed by C language
- implementation scheme for all components using method of software
engineering
3. Implementation and Verification
- components assembled and executed on both SMU and SDIU
- configuration of the software components and the operating system
are pretty much the same
- main differences are:
- 1553B convergence component :BC mode on SMU and RT mode
on SDIU
- Some PUS components not included in SDIU
- Some configurations different (route table, device access table,
device data pool configuration,etc.)
3. Implementation and Verification
- verified on tornado vxSim platform
- result shows that the change of hardware interface and protocols can
be adapted by the design of the architecture
- different requirements can be realized by the combination of service
components
- reusability of the software is well proved
- to be tested and verified on the hardware in the future
Catalogue
Introduction1
Software Architecture Design2
Implementation and Verification3
Conclusion4
4. Conclusion
- Aiming at the trend of the function integration, synthesis and fast
software development on spacecraft avionics system, the avionics
system software architecture designed can adapt to the change of
hardware interface, protocol and user requirements through layered
design and the integration of several standard services and protocols.
Thus the development of application software will be more flexible
and efficient which will benefit the reuse of avionics system software
so that the spacecraft life cycle will be shortened and the cost will be
saved.
4. Conclusion
- There are still some other problems that still need to be concerned on
the architecture, such as how to support the partition management of
operating system, how to realize the visualized assemble of software
components and the visualized simulation of information flow, etc.
Thank you !
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