Using IoT Device Technology in
Spacecraft Checkout Systems
By Chris Plummer
Space EGSE Ltd
Presentation to DASIA 2015
20th May, 2015
Outline of the presentation
• What we are trying to achieve
• The anatomy of a spacecraft checkout system
• What is the Internet-of-Things?
• The anatomy of a ‘thing’
• The development story so far
• Product examples
• Where do we go from here?
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What we are trying to achieve
• Physically much smaller systems
• Significantly shorter delivery times
• Lower cost systems
• More versatile and flexible systems
• Much better scalability
• Requiring significantly reduced integration effort
• Improved usability
• Greater reuse potential
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The anatomy of a spacecraft checkout system - 1
Overall system
Checkout
System
Controller
EGSE LAN
TM/TC
SCOE
DHS
SCOE
AOCS
SCOE
Power
SCOE
Payload
SCOE
Spacecraft Under Test
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The anatomy of a spacecraft checkout system - 2
SCOE architecture
Back-end LAN Interface to Checkout System Controller
SCOE Controller Computer
Rack Internal Interconnects
Hardware Interface Modules (examples)
Pulse
Command
Outputs
Thermistor
Sims
1553
Bus
Analogue
Acquisition
SpaceWire
Links
Front-end Interfaces to Spacecraft
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What is the Internet-of-Things
The expression “Internet-of-Things” describes the notion of a
collection of embedded computing devices interconnected through
the cloud-like infrastructure of the internet.
An excellent example of a real internet of things can be seen with
smartphones.
The smartphone is a ‘thing’, the mobile network it attaches to is the
cloud-like infrastructure.
But there are many other emerging examples, such as:
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What is the Internet-of-Things (examples)
• Home automation systems, where the ‘things’ are switches,
lamps, thermostats, motion sensors, etc.
• Automotive systems, where cars are the ‘things’.
• Patient monitoring systems, where the ‘things’ are medical
sensors attached to patients.
• Asset tracking systems, where the ‘things’ are smart tags and
monitoring devices attached to goods.
• POS and ATM networks, where the ‘things’ are cash registers and
dispensers.
• Video gaming systems, where the ‘things’ are the gaming
consoles, hand controllers, and so on.
And the list just keeps growing!
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The anatomy of a ‘thing’
Wired/Wireless Internetworking Interface
Embedded Controller/Computer
Internal Interconnects
Peripheral Interface Modules (examples)
GPIO
Sensor I/Fs
(SPI, I2C)
USB
Analogue
Acquisition
Serial I/Fs
(UART,
USART)
Physical Interfaces to Sensors and Actuators
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The development story so far
• Identified appropriate technology/devices
• Designed an architecture appropriate for modules
applicable to spacecraft checkout systems
• Developed libraries of software modules to enable
rapid development of specific products
• Developed early prototypes of what we consider to
be key products
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IoT Candidate Technologies
The key technology of interest is the general purpose SoCs that have
been developed to meet the needs of ‘things’ by manufacturers such
as Freescale and ST Microelectronics.
These can be classed into a number of families that are mainly differentiated
by the core processor they are based on, the number of cores available, and
the type and number of integrated peripherals.
Two devices of particular interest have been identified:
• Freescale iMX6 series
• STMicroelectronics STM32F4xx series
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STM32F407 SoC Block Diagram - 1
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STM32F407 SoC Block Diagram - 2
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STM32F407 SoC Block Diagram - 3
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STM32F407 SoC
Timer Peripheral
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Module Architecture
Back-end LAN Interface to Checkout System Controller
Embedded
Computer
SCOE Controller Computer
Rack Internal Interconnects
Hardware Interface Modules (examples)
Pulse
Command
Outputs
Thermistor
Sims
1553
Bus
Analogue
Acquisition
SpaceWire
Links
MicroController
Module
Specific
I/O
Front-end Interfaces to Spacecraft
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Software Libraries - 1
For the ARM Cortex A9 embedded controller we have a software
framework that includes:
• Generic TCP and UDP link classes
• EDEN and PUS packet handlers
• Command handler
• Debug interface
• XML libraries
In addition, we have an ECSS compliant TM/TC stack including:
• Packet, segment, and frame level encoding and decoding for TC and TM
• COP-1 dynamically established and maintained on all active virtual channels
• TC authentication using NIST800.38B CMAC authentication codes with key
management and anti-replay counters
• A range of standard codecs
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Software Libraries - 2
For the ARM M4 microcontroller we have implementations of:
• RUAG RF bypass interfaces, including TM frame synchroniser
• DMA based SPI interface control for variable length message transfer at up
to 42Mbps
• Bit-banged 1553 transmit and receive interfaces
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Prototype Modules - 1
Two prototype modules have been developed:
• A 32-channel thermistor simulator module
• A compact TM/TC baseband module
The choice of prototype modules was carefully considered in order to explore
the widest range of capabilities and benefits provided by the SoC based
modules.
The thermistor simulator was chosen as an example of a low tech, plain vanilla
type of EGSE module. We wanted to demonstrate that the SoC technology
offered benefits of scalability, and reduced cost-per-channel for simple
interfaces.
The compact baseband interface was selected because it is technically
challenging in terms of processing and performance in the Cortex A9.
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Prototype Modules - 2
Both prototype modules have been implemented with surprising
ease and are in the advanced stages of testing
In particular for the compact baseband interface, the performance of even the
single core i.MX6 SoC proved more than adequate for typical S-band data
rates.
Both modules are remotely controlled through an EDEN interface using PUS
packets. They can therefore be controlled through dedicated Windows form
based control panels, or via the Terma TSC/CCS products.
Integration of the modules into the checkout system is trivial. In the case of
using dedicated Windows forms, the control application is simply loaded onto
the host computer and started. In the case of a TSC/CCS environment, the
provided MIBs and control scripts are simply copied into the test environment
and run during a test session.
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Product examples - 1
There are a number of modules that we think are good candidates
for this technology in the future:
• Typical standard interfaces such as bi-level discretes, pulse commands,
switch interfaces, etc.
• A debug support unit (DSU) interface module that combines the software
load and debug serial interfaces with the discrete control and status
signals required for the DSU interface. Combined with the compact
baseband module, this would enable early flight software development
with minimal EGSE.
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Product examples - 2
• Hardware-in-the-loop simulator modules for key components, such as
gyros, star trackers, etc. that are form, fit, and function compatible at the
electrical level. E.g. an Astrix gyro simulator could provide the discrete
pulse and status interfaces, 1553 control bus interface, and RS-422
control and stimulus interfaces on identical connectors to the real unit
for use in EMs and flatsat models.
• Multi-channel heater control modules to provide precisely controlled
PWM power inputs for test heaters and thermal test dummies
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Where do we go from here?
We believe that IoT SoC technology can offer huge benefits in
spacecraft checkout systems and can achieve the goals set out in this
presentation, including reduced size, faster development, lower
cost, ease of integration, and so on..
Our immediate next steps are to develop the prototypes that we already have
into production grade designs.
We are in a position where we can rapidly develop new products using our
module architecture and the software libraries and will start developing other
related products outlined above.
We would welcome input from potential customers and users of our products.
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