1. Using IoT Device Technology in Spacecraft Checkout Systems
By Chris Plummer
Space EGSE Ltd
Presentation to DASIA 2015
20th May, 2015

2. Using IoT Device Technology for Spacecraft Checkout Systems
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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Using IoT Device Technology for Spacecraft Checkout Systems

3. Using IoT Device Technology for Spacecraft Checkout Systems
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
Size really does matter these days. Floor space is at a premium in most cleanrooms, especially on programs like Galileo and MTG, where there are several spacecraft being integrated at the same time.
Shorter delivery times are important because checkout systems are generally the last thing specified and the first thing needed. The checkout system is always on, or precariously close to, the critical path.
Lower cost not just in terms of the initial procurement costs, but in overall cost of ownership over the whole project lifecycle.
By versatility and flexibility we particularly mean the ability to combine modules without restrictions in order to meet the requirements of a specific spacecraft, but this also refers to the ability to adapt individual modules to offer new features without major rework at a system level.
Scalability means the ability to increase or decrease the number of channels of any particular interface type, as well as the ability to combine interface types within a single system, in order to meet specific spacecraft requirements
Reduced integration effort is extremely important because, in our experience, the initial procurement is only half the story. Integration of the complete system is a major challenge and is invariably underestimated, especially when each of the components has its own unique way of being operated. Integration is both a major cost factor, and determines the earliest availability of the system.
Improved usability in the sense that the system is easier to learn and operate. In particular, we think it is important that all components of the system are operated in the same way, regardless of the specific functions of that component.
Reuse applies at many levels, reuse of whole systems, reuse of individual components of a system, reuse of designs, reuse of specifications, and so on.
Improved usability
Greater reuse potential
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Using IoT Device Technology for Spacecraft Checkout Systems

4. 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
The traditional checkout system architecture consists of:
A set of Special CheckOut Electronics (SCOE) racks that provide subsystem specific interfaces to the test article.
A Checkout System Controller that coordinates the actions of the SCOEs to perform system level tests.
The SCOEs differ in terms of the types, and numbers of interfaces that they provide, and to the functions that they provide, such as simulation of AOCS sensors.
The SCOEs shown are typical, but other SCOE types are also commonly required, e.g. thermal EGSE, Pyro SCOEs, etc.
This architecture is not confined to the space industry. Equivalent architectures are found across many different industries, including automotive, aircraft, and consumer electronics.
It is a common misconception that the SCOEs must perform complex measurements and simulate bizarre behavioural traits on the interfaces. This is actually the job of unit testers that are used before spacecraft integration and test. The SCOEs normally provide ‘plain vanilla’ interfaces to the spacecraft under test.
Spacecraft Under Test
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Using IoT Device Technology for Spacecraft Checkout Systems

5. The anatomy of a spacecraft checkout system - 2
SCOE architecture
Back-end LAN Interface to Checkout System Controller
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
A typical SCOE architecture consists of:
A SCOE Controller Computer that controls the front-end hardware and provides local control interfaces and the back-end interface to the Checkout System Controller.
A number of modules providing the hardware interfaces to the spacecraft under test.
Rack internal interconnects between the controller computer and the hardware modules.
Note: Only limited examples of the hardware interface modules are shown.
The rack internal interconnects are usually of several types. Older systems are predominantly backplane buses, such as VME and PCI, but on newer systems we see an increase in serial buses such as USB and LAN.
Front-end Interfaces to Spacecraft
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Using IoT Device Technology for Spacecraft Checkout Systems

6. Using IoT Device Technology for Spacecraft Checkout Systems
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.
What we are actually interested in here are the ‘things’. The cloud-like stuff is basically built on top of existing technology and infrastructure, such as server farms. But the ‘things’ are where the real technical innovation is happening.
In order to make ‘things’ practical, they have got to be made small, cheap, low power consuming, capable, and easily reproducible.
So we are really interested in what is going on in terms of technology development for ‘things’.
But there are many other emerging examples, such as:
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Using IoT Device Technology for Spacecraft Checkout Systems

7. Using IoT Device Technology for Spacecraft Checkout Systems
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.
The variety here is very interesting because of the implications that each application has on the capabilities that must be provided by the ‘thing. For example:
All applications imply a physical I/O capability to sensors and actuators built into the ‘thing’, such as buttons, displays, mass memory, and so on.
Medical and automotive systems have extreme reliability and safety implications.
Asset tracking and home automation systems typically imply very small sizes and low power.
POS and ATM networks in particular have extreme security implications.
Video gaming and other consumer related applications imply low cost.
Many applications, POS/ATM, medical, automotive, imply precise synchronization requirements.
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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Using IoT Device Technology for Spacecraft Checkout Systems

8. 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)
The embedded controller/computer is the critical element that makes the ‘thing’ capable of operating within an internetworking environment. This is what makes the ‘thing’ smart.
The capabilities required of the embedded controller/computer will vary across different applications. For example, the embedded controller/computer required in a smart phone needs to be capable of supporting applications running on an operating system such as Android, while in an automotive or medical application it might need to support hard real-time behavior with or without an operating system.
Typically, the back-end interface to the ‘Internet’ can be wireless or wired depending on the application, but it is important that it is a ubiquitous interface such as , Bluetooth, or similar. The required data throughput on this interface also varies between applications.
The actual number and types of physical interfaces that a ‘thing’ supports is also highly variable. Those commonly found are GPIO, and SPI and I2C and their derivatives. However, serial interfaces like USB, and UARTs and USARTS are very common, as are both analogue input and output interfaces.
The internal interconnects between the embedded controller/computer depend on how the ‘thing’ is implemented, and in particular on how tightly it is integrated. These interfaces range from general purpose parallel and serial buses like AMBA and AHB buses, to more specific buses like the CSI camera interface bus.
Physical Interfaces to Sensors and Actuators
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Using IoT Device Technology for Spacecraft Checkout Systems

9. Using IoT Device Technology for Spacecraft Checkout Systems
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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Using IoT Device Technology for Spacecraft Checkout Systems

10. Using IoT Device Technology for Spacecraft Checkout Systems
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
IoT SoCs consist of a processor core together with a number of peripheral devices integrated onto a single chip.
The processor cores are targeted for specific types of ‘thing’ according to whether the ‘thing’ is predominantly processing, e.g. video and audio players, encryption devices, etc., or predominantly I/O based, such as game controllers, sensor devices, and so on.
The same considerations also affect the number and type of peripherals that are integrated. ‘Things’ that are processor intensive also tend to require high level communication peripherals such as Ethernet controllers, and require less general purpose I/O, whereas I/O intensive ‘things’ need more low level general purpose I/O channels and low level communication interfaces like SPI and I2C controllers.
STMicroelectronics STM32F4xx series
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Using IoT Device Technology for Spacecraft Checkout Systems

11. Using IoT Device Technology for Spacecraft Checkout Systems
There are a number of very interesting features to note here, starting with the CPU platform. This is based on an ARM Cortex A9 core. ARM cores come in three flavours; A, for application intensive targets, M, for I/O intensive targets, and R, for real-time targets. This SoC uses an A9 core and runs at up to 1GHz, but to get even higher performance the core includes the NEON 128-bit SIMD accelerator.
Another area of interest is the multimedia block. This actually consists of a VPU and GPU which can be user programmed to perform number crunching activities.
The security block includes hardware accelerators for NIST encryption and authentication with a number of algorithms, including AES, which further unloads the core processor module.
The connectivity block provides a raft of interfaces to external devices, including USB, UARTs, SPI, and so on, but one of the most important interfaces is the 1Gb Ethernet peripheral that has full hardware support for the IEEE Precision Time Protocol.
This all adds up to a device with amazing performance potential, but this is only the single core version of the chip. It is also available in dual and quad core versions!
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Using IoT Device Technology for Spacecraft Checkout Systems

12. Using IoT Device Technology for Spacecraft Checkout Systems
STM32F407 SoC Block Diagram - 1
The STM32F407xx series of devices are targeted at more I/O intensive applications. This device is so packed with peripherals that we have had to split the architecture block diagram over three slides. This first slide mainly shows the processor block, which features an ARM M4 core that can operate at 168MHz, together with an integrated Floating Point Unit.
Note also the Nested Vectored Interrupt Controller, NVIC, in this block. This allows hardware interrupts from a large number of sources both on and external to the chip to be filtered, prioritized, and associated to a specific interrupt vector, which enables the processor to respond very quickly to real events without polling.
Also worthy of note on this part of the block diagram is the pair of DMA controller peripherals. These each have eight independent DMA streams, each of eight channels that enable a wide range of memory<->peripheral and memory<->memory DMA paths to be established and thereby unburden the core processor from a lot of the low level I/O activities.
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Using IoT Device Technology for Spacecraft Checkout Systems

13. Using IoT Device Technology for Spacecraft Checkout Systems
STM32F407 SoC Block Diagram - 2
The next section of the STM32F407xx block diagram mainly shows the GPIO channels available. Nine 16-bit GPIO ports are available giving a total of 144 GPIO lines that can be configured as inputs or outputs, and can be programmed to generate interrupts on rising, falling, or both edge transitions, and can be configured with pull-up, pull-down resistors, or neither, for push-pull or open drain operation.
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Using IoT Device Technology for Spacecraft Checkout Systems

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STM32F407 SoC Block Diagram - 3
The last part of the STM32F407xx block diagram is where things really get busy. The notable peripherals that can be seen here are the timers, fourteen of them, most being four channel timer/counters, the USART and UART serial interfaces, six in total, and the SPI interfaces.
But also there are I2C, ADC and DAC interfaces available.
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Using IoT Device Technology for Spacecraft Checkout Systems

15. Using IoT Device Technology for Spacecraft Checkout Systems
STM32F407 SoC
Timer Peripheral
This slide expands just one of the available peripheral types, namely the general purpose timer, to illustrate the sort of capability that is provided. There are actually ten timers like this available on the chip! Of the other four timers on the chip, two are actually more complex, while two are slightly simpler.
Apart from the incredible configurability of these timers, which can be used to count events, measure durations, generate periodic signals with configurable duty cycles, and so on, note the number of configurable interrupt sources. These allow the system to be configured so that the processor core can be configured to respond very rapidly to very specific events, and ensures both minimal cycle wastage on the processor, and a very fast responses to events.
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Using IoT Device Technology for Spacecraft Checkout Systems

16. Module Architecture Embedded Computer SCOE Controller Computer
Back-end LAN Interface to Checkout System Controller
Back-end LAN Interface to Checkout System Controller
SCOE Controller Computer
Embedded Computer
Rack Internal Interconnects
Hardware Interface Modules (examples)
Micro-Controller
Pulse Command Outputs
Thermistor
Sims
1553 Bus
Analogue Acquisition
SpaceWire Links
Revisiting the traditional SCOE architecture, the IoT SoC technology allows us to rethink how we modularize the system. The cost of providing the control function is now so low that simplistically we can just slice it vertically so that for each interface type, e.g. pulse command, thermistor, bi-level discrete, etc., we have an embedded controller. This actually makes a lot of sense for some classes of interface, particularly those with high channel count like HPC, BSM, TSM, and so on, and leads to highly scalable systems.
But it also does not preclude us having multiple interface types on a single module when that makes sense, for example if we are simulating a device that has a 1553 control bus, but requires HPC pulses to turn it on and of, and delivers a bi-level discrete power on status signal. In fact the SoCs are highly amenable to this.
The resulting module architecture is shown on the right. Instead of a single LAN interface to the checkout system controller there is now one LAN interface per module. This is generally not a problem because LAN switches are cheap and can be deployed appropriately to minimize cabling. If IEEE1588 is used, the LAN also enables very high precision synchronization between the modules so we no longer need monstrosities like IRIG-B for this. Note also that the rack internal interconnects are eliminated in most cases that we can envisage.
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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18. Using IoT Device Technology for Spacecraft Checkout Systems
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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Using IoT Device Technology for Spacecraft Checkout Systems

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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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Using IoT Device Technology for Spacecraft Checkout Systems

23. Using IoT Device Technology for Spacecraft Checkout Systems
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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Using IoT Device Technology for Spacecraft Checkout Systems