SpaceWire EGSE - STAR
SpaceWire EGSE
The SpaceWire Electronic Ground Support Equipment (EGSE) is a
test and development unit that simulates instruments or other
SpaceWire equipment in real-time. The EGSE is configured using a
simple yet powerful scripting language designed specifically for
SpaceWire applications. Once configured the EGSE operates
independent of software resulting in real-time performance. This
can be used to rapidly mimic the behaviour of SpaceWire
equipment, vastly reducing traditional development time, risk
and cost associated with writing equivalent software in a realtime operating system.
The SpaceWire EGSE can generate detailed packets in pre-defined
sequences at specific times and data rates, controlled by state
machines and events. It is an extremely useful tool during
equipment development and validation, and spacecraft assembly,
integration and test. Using the SpaceWire EGSE and its associated
scripting language it is possible to produce a complete SpaceWire
instrument simulation in little more than a day.
Key Features
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Emulates SpaceWire traffic from almost any instrument, or
other flight equipment in real-time.
Generates sophisticated sequences of packets with varying
payload content, timing and data-rates.
Stores pre-defined packet cargoes in memory to emulate
large payloads from high data-rate instruments.
Monitors received packet streams, reacting to preprogrammed sequences.
Interacts with external hardware through external triggers,
which can be used to trigger different packet sequences.
Interacts with host software via software event and the
provided API to trigger packet sequences for real-time
transmission.
Notifies host software of state changes and events.
Link data-signalling rates can be changed on the fly, with
high resolution, enabling close simulation of an instrument
or other SpaceWire unit.Supports time-code generation and
can act as a time-code master.
Highly configurable using the powerful and intuitive scripting
language.
SpaceWire EGSE Front View
Features
Two SpaceWire interfaces: Each fully compatible with the
SpaceWire standard and able to operate at up to 200 Mbits/s. Tricolour LEDs for each link indicate status and activity.
External triggers: To integrate with external equipment the EGSE
has three external input triggers and one external output trigger.
The external input triggers can be used to change the behaviour
of the EGSE in response to an input signal. The external output
trigger can generate a signal in response to an event, such as the
receipt of a specific packet. This can be used to trigger
oscilloscopes, logic analysers, or other test equipment to make
measurements concurrent with sequences generated by the
EGSE.
Large memory: 128MBytes for storing pre-defined packet.
USB 2.0 interface: Provides a high speed connection between the
host PC or laptop to the EGSE.
19” rack mountable: Readily mounted in a 1U high, 19” rack
alongside other STAR-Dundee products using STAR-Dundee’s rack
mounting kit. Up to four EGSEs can be mounted on a 1U shelf.
SpaceWire EGSE Operation
The SpaceWire EGSE comprises a SpaceWire interface unit and
software running on a host PC. The interface unit connects to the
host PC using a USB 2.0 cable and is powered via a 5V power
brick.
The interface unit is configured using a user authored script that
is compiled and loaded onto the SpaceWire EGSE unit. Once
configured, it can generate complex SpaceWire packet sequences
without further interaction from host PC software.
# Set the line rates to 200Mbits/s
config
spw_tx_rate(1, 200Mbps)
spw_tx_rate(2, 200Mbps)
end config
# Packet defined with 8 hex
# bytes followed by EOP
packet pkt1
hex(0A FF 34 C8 11 4D 54 AB)
eop
end packet
# Send “pkt1” 0.5s after schedule
# starts at 100Mbps
schedule schedule1 @ 100Mbps
500ms send pkt1
end schedule
# SpW link 1 state machine
statemachine 1
# State in which “schedule1”
# is executed repeatedly
state state1
do schedule1 repeatedly
end state
end statemachine
Simple SpaceWire EGSE Script
The SpaceWire EGSE’s ability to generate packets independent of
host software means it can operate in real-time, closely
mimicking the packet generation behaviour of an instrument or
other SpaceWire equipment.
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Time-code transmitted: React to the transmission of a timecode from a SpaceWire interface.
Received pattern matched: Transition from one state to
another when the SpaceWire traffic received on an interface
matches a specified pattern.
Software
The EGSE is supplied with software comprising:
Compiler and loader: Compile scripts and configure the
SpaceWire EGSE using these command line applications.
C API: Write custom software to interact with the EGSE.
Trace of Generated Packet Sequence
The screenshot above is taken from a SpaceWire Link Analyser
Mk2 and demonstrates the high data rates that can be achieved.
It shows the EGSE generating a sequence of small packets on both
SpaceWire links, running at 200MHz with no NULL characters in
the trace.
SpaceWire EGSE Scripting
The SpaceWire EGSE is configured using a simple yet powerful
scripting language that was designed specifically for SpaceWire
applications:
Packet definitions: Can consist of data defined in hexadecimal or
decimal bytes, data imported from file, variable references, CRC
and checksum calculations, EEP and EOP markers and time-code
manager instructions.
Variables: Used to define packets with dynamic data. Declared
variables can be referenced in packet definitions. The value
produced by a variable reference is dependent on its type:
constant, random, increment, decrement, rotate right and rotate
left. CRC and checksum variables are used to perform CRC and
checksum calculations.
Schedules: Define the sequence, timing and data rate at which
pre-defined packets are transmitted.
State machines: Responsible for control of the EGSE state. Each
state in a state machine is associated with a schedule which is
executed when that state is entered. State transition statements
specify the event(s) on which to transition from one state to
another.
Events: Used to control the current state of the SpaceWire EGSE
state machines and therefore the current packet generation
schedule. The different event types are:
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Software: Transition from one state to another in response
to events generated from host software.
State machine: Raise an event when a state of interest is
entered.
External trigger in: React to an external input trigger signal
received from other equipment.
External trigger out: Generate an external trigger output
signal in response to an event of interest.
Time-code received: React to the receipt of a time-code on a
SpaceWire interface.
GUI: Combines a text editor, for creating and modifying EGSE
scripts, with much of the functionality provided by the compiler,
loader and C API including: script compilation, EGSE
configuration, software event generation, state and event
notification monitoring and periodic time-code generation.
Upgrades and Support
Field upgradable: Upgrades and requested customisations can
be downloaded from the STAR-Dundee website and installed
quickly and efficiently.
First class support: As with all of STAR-Dundee’s products, a
year’s support and maintenance is included with the SpaceWire
EGSE. Support is provided directly from the team that developed
the product allowing us to respond quickly with answers to
customer questions, give assistance with application
development, and resolve any problems quickly.
Specifications
Size: 110 x 30 x 112 mm (excluding feet).
Power: +5V DC, power brick supplied.
SpaceWire Ports:
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2 SpaceWire ports, micro-D connectors located on the front
panel.
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ECSS-E50-12A and ECSS-E-ST-50-12C compliant.
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Maximum Speed: 200 Mbits/s each port.
USB 2.0:
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High Speed 480 Mbits/s.
Trigger input and output:
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3 dedicated trigger inputs; 1 on front panel, 2 on the rear
panel
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1 dedicated trigger output on front panel
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SMB connectors with +3.3V signal level and 5V tolerances.
Mictor logic analyser connectors:
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2 on the rear panel show device state
API: C language.
Supporting software included:
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Operates under Windows (Windows 7, Vista, XP, 2000) and
Linux (2.6 and 3 kernels).
Application Notes
Application notes are available that describe how the SpaceWire
EGSE can be used to emulate SpaceWire devices and integrate
with spacecraft EGSE equipment; see www.star-dundee.com.
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