SIST EN 16603-50-12:2020
(Main)Space engineering - SpaceWire - Links, nodes, routers and networks
Space engineering - SpaceWire - Links, nodes, routers and networks
This Standard specifies the physical interconnection media and data communication protocols to enable the reliable sending of data at highspeed (between 2 Mb/s and 400 Mb/s) from one unit to another. SpaceWire links are fullduplex, pointtopoint, serial data communication links.
The scope of this Standard is the physical connectors and cables, electrical properties, and logical protocols that comprise the SpaceWire data link. SpaceWire provides a means of sending packets of information from a source node to a specified destination node. SpaceWire does not specify the contents of the packets of information.
This Standard covers the following protocol levels:
• Physical level: Defines connectors, cables, cable assemblies and printed circuit board tracks.
• Signal level: Defines signal encoding, voltage levels, noise margins, and data signalling rates.
• Character level: Defines the data and control characters used to manage the flow of data across a link.
• Exchange level: Defines the protocol for link initialization, flow control, link error detection and link error recovery.
• Packet level: Defines how data for transmission over a SpaceWire link is split up into packets.
• Network level: Defines the structure of a SpaceWire network and the way in which packets are transferred from a source node to a destination node across a network. It also defines how link errors and network level errors are handled.
This Standard may be tailored for the specific characteristics and constraints of a space project in conformance with ECSS-S-ST-00.
Raumfahrttechnik - SpaceWire - Verbindungen, Knoten, Router und Netzwerke
Ingénierie spatiale - SpaceWire - Liens, nœuds, routeurs et réseaux
La technologie SpaceWire s'est développée à partir des besoins des applications de
traitement des données embarquées sur les engins spatiaux. La présente norme fournit
une base formelle pour l'exploitation de SpaceWire dans une large gamme de futurs
systèmes de traitement embarqués.
L'un des principaux objectifs de SpaceWire est d'assurer la compatibilité et la
réutilisation des équipements au niveau des composants et des sous-systèmes. En
principe, un système de traitement des données développé pour un instrument optique,
par exemple, peut servir à un instrument radar en débranchant le capteur optique et en
branchant celui du radar. Les unités de traitement, les unités de mémoire de masse et les
systèmes de télémétrie sur liaison descendante mis au point pour une mission peuvent
être facilement utilisés dans le cadre d'une autre mission, ce qui réduit le coût du
développement, améliore la fiabilité et, surtout, augmente le volume de travail
scientifique qui peut être réalisé avec un budget limité.
L'intégration et le test de systèmes embarqués complexes sont également pris en charge
par SpaceWire avec des équipements de support au sol se branchant directement sur le
système de traitement des données embarqué. La surveillance et les tests peuvent être
effectués grâce à une interface transparente avec le système embarqué.
SpaceWire est le résultat des efforts conjugués de nombreuses personnes au sein de
l'Agence Spatiale Européenne, de l'industrie spatiale européenne et du monde
universitaire.
La présente norme peut être adaptée aux caractéristiques et contraintes spécifiques d'un
projet spatial, conformément à l'ECSS-S-ST-00.
Vesoljska tehnika - SpaceWire - Povezave, vozlišča, usmerjevalniki in omrežja
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-junij-2020
Vesoljska tehnika - SpaceWire - Povezave, vozlišča, usmerjevalniki in omrežja
Space engineering - SpaceWire - Links, nodes, routers and networks
Raumfahrttechnik - SpaceWire - Verbindungen, Knoten, Router und Netzwerke
Ingénierie spatiale - SpaceWire - Liens, nœuds, routeurs et réseaux
Ta slovenski standard je istoveten z: EN 16603-50-12:2020
ICS:
49.140 Vesoljski sistemi in operacije Space systems and
operations
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD
EN 16603-50-12
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2020
ICS 49.140
English version
Space engineering - SpaceWire - Links, nodes, routers and
networks
Ingénierie spatiale - SpaceWire - Liaisons, noeuds, Raumfahrttechnik - SpaceWire - Verbindungen,
routeurs et réseaux Knoten, Router und Netzwerke
This European Standard was approved by CEN on 29 December 2019.
CEN and CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for
giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical
references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to
any CEN and CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN and CENELEC member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.
CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium,
Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia,
Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
CEN-CENELEC Management Centre:
Rue de la Science 23, B-1040 Brussels
© 2020 CEN/CENELEC All rights of exploitation in any form and by any means Ref. No. EN 16603-50-12:2020 E
reserved worldwide for CEN national Members and for
CENELEC Members.
Table of contents
European Foreword . 7
1 Scope . 8
2 Normative references . 9
3 Terms, definitions and abbreviated terms . 10
3.1 Terms from other standards . 10
3.2 Terms specific to the present standard . 10
3.3 Abbreviated terms. 20
3.4 Conventions. 21
3.4.1 Numbers . 21
3.4.2 Differential signals . 21
3.4.3 Order of sending bits in symbols . 21
3.4.4 Graphical representation of packets . 22
3.4.5 State diagram notation . 22
3.4.6 UML diagram notation . 23
3.5 Nomenclature . 24
4 Overview of SpaceWire . 25
4.1 Introduction . 25
4.2 SpaceWire Spacecraft Data-Handling Network . 25
4.2.1 The Rationale for SpaceWire . 25
4.2.2 Example SpaceWire Application . 26
4.2.3 How SpaceWire Works . 28
5 Requirements . 33
5.1 Overview . 33
5.2 Protocol stack and interface architecture . 33
5.2.1 Protocol stack . 33
5.2.2 Network layer . 34
5.2.3 Data Link layer . 34
5.2.4 Encoding layer . 35
5.2.5 Physical layer . 35
5.2.6 Management Information Base . 36
5.2.7 Service interfaces . 36
5.2.8 SpaceWire Port architecture . 36
5.3 Physical layer . 37
5.3.1 Introduction . 37
5.3.2 Cables . 38
5.3.3 Connectors . 41
5.3.4 Cable assemblies . 45
5.3.5 PCB tracks . 50
5.3.6 Line drivers and receivers . 51
5.3.7 Data-Strobe skew . 59
5.3.8 Physical layer management parameters . 62
5.4 Encoding layer . 63
5.4.1 Introduction . 63
5.4.2 Serialisation and de-serialisation . 63
5.4.3 Character and control code encoding . 63
5.4.4 Data strobe encoding and decoding . 66
5.4.5 First Null . 68
5.4.6 Null detection . 68
5.4.7 Parity error . 69
5.4.8 Disconnect . 69
5.4.9 ESC error . 69
5.4.10 Data signalling rate . 70
5.4.11 Encoding layer management parameters . 71
5.5 Data link layer . 71
5.5.1 Introduction . 71
5.5.2 Data link layer interfaces . 71
5.5.3 Data link layer management interface . 72
5.5.4 Flow control. 73
5.5.5 Flow control errors . 74
5.5.6 Sending priority . 75
5.5.7 Link initialisation behaviour . 75
5.5.8 Link error recovery . 80
5.5.9 Accepting broadcast codes for sending . 82
5.6 SpaceWire network layer . 82
5.6.1 Introduction . 82
5.6.2 SpaceWire packets . 83
5.6.3 Broadcast codes . 83
5.6.4 SpaceWire time-codes . 84
5.6.5 SpaceWire distributed interrupts . 87
5.6.6 SpaceWire nodes . 94
5.6.7 SpaceWire node management parameters . 96
5.6.8 SpaceWire routing. 96
5.6.9 SpaceWire routing switch management parameters . 104
5.6.10 SpaceWire network . 104
5.7 SpaceWire management information base . 106
5.7.1 Introduction . 106
5.7.2 General . 106
5.7.3 Physical layer management parameters . 106
5.7.4 Encoding layer management parameters . 106
5.7.5 Data link layer management parameters . 106
5.7.6 Network layer management parameters . 106
6 Service interfaces . 107
6.1 Network layer service interface . 107
6.1.1 Packet service interface . 107
6.1.2 Time-code service interface . 108
6.1.3 Distributed interrupt service interface . 109
6.2 Data link layer service interface . 111
6.2.1 N-Char service interface. 111
6.2.2 Broadcast code service interface . 113
6.3 Encoding layer service interface . 114
6.3.1 Encoding service interface . 114
6.3.2 Decoding service interface . 115
6.4 Physical layer service interface . 117
6.4.1 Line transmit service interface . 117
6.4.2 Line receive service interface . 118
6.5 Management information base service interface . 119
6.5.1 Set parameter service interface. 119
6.5.2 Get parameter service interface . 119
Annex A (informative) Technical Changes . 121
Bibliography . 123
Figures
Figure 3-1: Convention for first bit to be sent . 21
Figure 3-2: Graphical packet notation . 22
Figure 3-3: State diagram style . 22
Figure 3-4: UML notation . 23
Figure 4-1: Example SpaceWire Architecture without redundancy . 27
Figure 4-2: SpaceWire Packet Format . 29
Figure 4-3: Path Addressing . 31
Figure 4-4 Logical Addressing . 32
Figure 5-1: SpaceWire protocol stack . 34
Figure 5-2: SpaceWire port architecture . 37
Figure 5-3: SpaceWire connector contact identification . 44
Figure 5-4: SpaceWire cable assembly Type A . 47
Figure 5-5: SpaceWire cable assembly Type AL . 49
Figure 5-6: SpaceWire LVDS . 53
Figure 5-7: LVDS line driver output signals. 54
Figure 5-8: LVDS line driver differential output signal . 56
Figure 5-9: Physical layer components . 59
Figure 5-10: Skew and jitter . 62
Figure 5-11: Data character encoding . 64
Figure 5-12: Control character encoding . 65
Figure 5-13: Null control code encoding . 65
Figure 5-14: Broadcast code encoding . 66
Figure 5-15: Parity coverage . 66
Figure 5-16: Data-Strobe (DS) encoding . 67
Figure 5-17: Data and strobe signals for first Null . 68
Figure 5-18: Null detection sequence . 69
Figure 5-19: Link initialisation behaviour . 76
Figure 5-20: Link error recovery behaviour . 81
Figure 5-21: SpaceWire packet format . 83
Figure 5-22: Specialisations and relationships of a SpaceWire broadcast code . 84
Figure 5-23 Network layer time-code . 85
Figure 5-24: Network layer interrupt . 88
Figure 5-25: Network layer interrupt acknowledgement code . 89
Figure 5-26: Components and specialisations of a SpaceWire node . 95
Figure 5-27: Components of a SpaceWire routing switch . 97
Figure 5-28: Components of a SpaceWire network . 105
Tables
Table 5-1: Constants for a SpW cable using 28 AWG differential pairs . 39
Table 5-2: Insertion loss values 28AWG SpW cable . 40
Table 5-3: Constants for a SpaceWire cable using 26 AWG differential pairs . 40
Table 5-4: Insertion loss values for 26 AWG SpaceWire cable . 40
Table 5-5: Cable PSNEXT specification . 41
Table 5-6: Cable PSELFEXT specification . 41
Table 5-7: Connector contact identification . 43
Table 5-8: Cable assembly Type A signal wire connections . 47
Table 5-9: Cable assembly Type AL signal wire connections . 49
Table 5-10 Example calculation of maximum bit rate . 61
Table 5-11: Address function . 99
European Foreword
This document (EN 16603-50-12:2020) has been prepared by Technical
Committee CEN-CENELEC/TC 5 “Space”, the secretariat of which is held by
DIN.
This standard (EN 16603-50-12:2020) originates from ECSS-E-ST-50-12C Rev.1.
This European Standard shall be given the status of a national standard, either
by publication of an identical text or by endorsement, at the latest by September
2020, and conflicting national standards shall be withdrawn at the latest by
September 2020.
Attention is drawn to the possibility that some of the elements of this document
may be the subject of patent rights. CEN [and/or CENELEC] shall not be held
responsible for identifying any or all such patent rights.
This document has been prepared under a standardization request given to
CEN by the European Commission and the European Free Trade Association.
This document has been developed to cover specifically space systems and has
therefore precedence over any EN covering the same scope but with a wider
domain of applicability (e.g. : aerospace).
According to the CEN-CENELEC Internal Regulations, the national standards
organizations of the following countries are bound to implement this European
Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia,
Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
Scope
SpaceWire technology has grown from the needs of spacecraft on-board data
handling applications. This Standard provides a formal basis for the
exploitation of SpaceWire in a wide range of future on-board processing
systems.
One of the principal aims of SpaceWire is the support of equipment
compatibility and reuse at both the component and subsystem levels. In
principle a data-handling system developed for an optical instrument, for
example, can be used for a radar instrument by unplugging the optical sensor
and plugging in the radar one. Processing units, mass-memory units and down-
link telemetry systems developed for one mission can be readily used on
another mission, reducing the cost of development, improving reliability and
most importantly increasing the amount of scientific work that can be achieved
within a limited budget.
Integration and test of complex on-board systems is also supported by
SpaceWire with ground support equipment plugging directly into the on-board
data-handling system. Monitoring and testing can be carried out with a
seamless interface into the on-board system.
SpaceWire is the result of the efforts of many individuals within the European
Space Agency, European Space Industry and academia.
This standard may be tailored for the specific characteristics and constraints of a
space project in conformance with ECSS-S-ST-00.
Normative references
The following normative documents contain provisions which, through
reference in this text, constitute provisions of this ECSS Standard. For dated
references, subsequent amendments to, or revision of any of these publications
do not apply. However, parties to agreements based on this ECSS Standard are
encouraged to investigate the possibility of applying the more recent editions of
the normative documents indicated below. For undated references, the latest
edition of the publication referred to applies.
EN reference Reference in text Title
EN 16601-00-01 ECSS-S-ST-00-01 ECSS system - Glossary of terms
EN 16602-70-08 ECSS-Q-ST-70-08 Space product assurance - Manual soldering of high-
reliability electrical connections
EN 16602-70-26 ECSS-Q-ST-70-26 Space product assurance - Crimping of high-reliability
electrical connections
ESCC 3401 Connectors, electrical, non-filtered circular and
rectangular, ESCC Generic Specification no. 3401,
Issue 5, March 2018
ESCC 3401/029:2017 Connectors, Electrical, Rectangular, Microminiature,
based on type MDMA, ECSS Detail Specification no.
3401/029, Issue 15, November 2017.
ESCC 3401/077:2016 Connectors, Electrical, Rectangular, Microminiature,
Removable Crimp Contacts, based on type MDMA,
ECSS Detail Specification no. 3401/077, Issue 7, April
2016.
ESCC 3902/003:2014 Cable, “SpaceWire”, Round, Quad using Symmetric
Cables, Flexible, –200 to +180 °C, Detail Specification
no. 3902/003, Issue 4, November 2014.
ESCC 3902/004:2014 Cable, Low Mass, “SpaceWire”, Round, Quad using
Symmetric Cables, Flexible, –100 to +150 °C, Detail
Specification no. 3902/004, Issue 1, October 2014.
MIL-DTL-17J:2014 Military Specification: Cables, Radio, Frequency,
th
Flexible and Semirigid, General Specification for, 10
February 2014.
TIA-644-A:2012 TIA-644-A, Electrical Characteristics of Low Voltage
Differential Signalling (LVDS) Interface Circuits,
Revision A, Reaffirmed 12/07/12, Telecommunications
Industry Association, 2012.
Terms, definitions and abbreviated terms
3.1 Terms from other standards
For the purpose of this Standard, the terms and definitions from ECSS-S-ST-00-01
apply.
3.2 Terms specific to the present standard
The UML diagrams of Figure 5-22, Figure 5-26, Figure 5-27 and Figure 5-28 in
clause 5.6 illustrate the relationships between various terms used within this
standard.
3.2.1 allocated output port
output port that a packet is routed through
3.2.2 after 6,4 μs
delay of 6,4 μs (nominal) measured from when a state is entered
3.2.3 after 12,8 μs
delay of 12,8 μs (nominal) measured from when a state is entered
3.2.4 AutoStart
management parameter set by hardware or software which when asserted
allows an enabled SpaceWire port to start the SpaceWire link only when a Null
is received
3.2.5 bit error rate
ratio of the number of bits received in error to the total number of bits sent
across a link
3.2.6 broadcast code
time-code or distributed interrupt code
3.2.7 broadcast code identifier
two-bit code that identifies the type of broadcast code: 0b00 identifies a time-
code and 0b10 identifies a distributed interrupt code
3.2.8 byte
eight bits
3.2.9 cargo
some information for transfer from a source to a destination which is
encapsulated in a packet
3.2.10 character
control character or data character
3.2.11 coding
act of translating a set of bits into another set of bits which are more appropriate
for transmitting across a medium
3.2.12 configuration port
port in a routing switch or node that gives access to a configuration node
3.2.13 configuration node
type of node whose purpose is to configure the routing switch or node that it is
part of
3.2.14 control character
ESC, FCT, EOP or EEP character that is used to pass control information across
a link
3.2.15 control code
sequence of an ESC followed by an FCT forming a Null which is used to keep a
link active, or a sequence of an ESC character followed by a data character
forming a broadcast code which is used to broadcast time-codes and
distributed interrupt codes over a SpaceWire network
3.2.16 control symbol
control character encoded in 4-bits for transfer across a link
3.2.17 data character
character that is used to pass 8 bits of data across a link
3.2.18 data link layer
protocol layer which is responsible for the initialisation of a SpaceWire link, for
transferring packets and broadcast codes over the link and for recovery from
errors on the link
3.2.19 data rate
rate at which the application data is transferred across a link
3.2.20 data signalling rate
rate at which the bits constituting control and data symbols are transferred
across a link
3.2.21 data-strobe
sequence of data bits and bit clock encoded into two signals, one containing the
data bit sequence (data) and the other changing state whenever the data bit
sequence does not (strobe)
3.2.22 data symbol
data character encoded in 10 bits for transfer across a link
3.2.23 decoding
act of translating an encoded set of bits back into the original set of bits prior to
encoding
3.2.24 de-serialisation
transformation of a serial bit stream into a sequence of control or data symbols
3.2.25 destination
end-point that a packet is being sent to
3.2.26 destination address
route, described by a path address, to be taken by a packet in moving from
source to destination or an identifier, in the form of a logical address,
specifying the destination
3.2.27 destination node
node that is the destination of one or more SpaceWire packets
3.2.28 disconnect
indication from a receiver that there has been no edge on the data or strobe
signals for the past 850 ns (nominal) indicating that the link is disconnected
3.2.29 distributed interrupt
interrupt that is distributed to all or many nodes on the network
3.2.30 distributed interrupt code
broadcast code used to distribute interrupts over a SpaceWire network which
is either an interrupt code or an interrupt acknowledgement code
3.2.31 driver
electronic circuit that transmits signals across a particular transmission medium
3.2.32 driver ground
ground at the 0V pin or pins of the driver differential outputs
NOTE If the driver has one 0V for signals such as TTL
or CMOS, and a separate 0V for the differential
outputs, the driver ground is the 0V for the
differential outputs. The driver ground is a
ground plane or planes which provide
controlled impedance for the driver's
differential pairs.
3.2.33 encoding layer
protocol layer which is responsible for the encoding of characters into symbols,
symbol serialisation, data-strobe encoding of the serial bit stream, data-strobe
decoding, symbol de-serialisation and decoding of symbols into characters
3.2.34 end of packet marker
control character which indicates the end of a packet
3.2.35 end-point
interface between the network and a host system providing a single port into
the network
3.2.36 error recovery scheme
method for handling errors detected within a SpaceWire link
3.2.37 ESC
control character which is followed by another control character or data
character to form a control code
3.2.38 ESC error
invalid ESC sequence, formed from an ESC followed immediately by an EOP,
EEP, or ESC
3.2.39 FIFO port
port that has a FIFO interface rather than a SpaceWire interface
3.2.40 fall time
time during which a falling signal voltage is within the range of 80 % to 20 % of
the difference between the two steady state values
3.2.41 first Null
initial Null received without a parity error when the link state machine is not in
the ErrorReset state
3.2.42 flow control token
control character used to manage the flow of data across a link, and being
exchanged for eight N-Chars
3.2.43 gotBC
sometime after the first Null was received, a broadcast code has been received
without a parity error
3.2.44 gotFCT
sometime after the first Null was received, an FCT has been received without a
parity error
3.2.45 gotNchar
sometime after the first Null was received, an N-Char has been received
without a parity error
3.2.46 gotNull
first Null, after the receiver has been enabled, has been received without a
parity error
3.2.47 group adaptive routing
assignment of a set of several ports to a logical or path address so that when a
packet arrives with that address it is switched to one of the set of several ports
that is currently available to accept the packet or that becomes available first
3.2.48 host interface
interface to a host system
3.2.49 host system
system that is connected to a SpaceWire network via an end-point and which
uses the services of that SpaceWire network
3.2.50 input port
receive side of a port
3.2.51 interrupt acknowledgement code
code used to confirm that a distributed interrupt has reached the appropriate
interrupt handler
3.2.52 interrupt code
code used to distribute an interrupt over a SpaceWire network
3.2.53 interrupt destination
node that receives and handles a distributed interrupt
3.2.54 interrupt handler
node that is responsible for handling an interrupt code with a specific value of
interrupt identifier
3.2.55 interrupt identifier
5-bit value representing one of 32 possible interrupts, which is held in the value
field of an interrupt code and which identifies the particular interrupt being
carried by the interrupt code or being acknowledged by an interrupt
acknowledgement code
3.2.56 interrupt relay register
register in a routing switch that holds the current state of the distributed
th
interrupt where the i bit of the register relates to the interrupt identifier of
value i, and is used to prevent repeated circular propagation of distributed
interrupt codes
3.2.57 interrupt source
node that generates a distributed interrupt
3.2.58 jitter
random errors in the timing of a signal
3.2.59 L-Char
link character
3.2.60 leading data character
very first data character sent over a link after initialisation or the first data
character following the EOP or EEP that terminated the previous packet
3.2.61 line driver
electronic circuit that drives signals across a particular transmission medium
3.2.62 line receiver
electronic circuit that receives signals sent across a particular transmission
medium
3.2.63 link
bi-directional connection between two ports used to transfer packets and
broadcast codes between the two ports
3.2.64 link character
control character or control code which appears on the link only and is not
passed between the data link and network layers
NOTE The FCT and Null are the only link characters
3.2.65 LinkDisabled
management parameter which when asserted prevents a SpaceWire port from
operating
3.2.66 link error
disconnect error, parity error, ESC error or credit error
3.2.67 link receiver
receiver at an end of a SpaceWire link
3.2.68 LinkStart
management parameter set by hardware or software which when asserted
causes an enabled SpaceWire port to attempt to start the SpaceWire link by
sending Nulls
3.2.69 link transmitter
transmitter at an end of a SpaceWire link
3.2.70 logical address
data character which identifies the destination for the packet
3.2.71 low voltage differential signalling
particular form of differential signalling using low voltage signals
3.2.72 management parameter
configuration parameter, control variable or status variable of a SpaceWire
node or routing switch used to manage its operation
3.2.73 multicast
sending of the same packet through two or more output ports of a routing
switch concurrently
3.2.74 multicast set
set of output ports assigned to a logical address through which a packet with
that logical address is forwarded concurrently
3.2.75 N-Char
normal-character
3.2.76 network level
protocol level responsible for transferring packets across a SpaceWire network
from source node to destination node via links and routers
3.2.77 node
source or destination of SpaceWire packets and broadcast codes comprising
one or more end-points each providing an interface between a port and a host
system
3.2.78 normal-character
data character, EOP or EEP
3.2.79 Null
control code made up of an ESC followed by an FCT which is sent to keep the
data link active when there are no data or control characters to send, thus
preventing a disconnect
3.2.80 output port
transmit side of a port
3.2.81 packet
sequence of normal-characters comprising a destination address, cargo and an
end of packet marker
3.2.82 path address
series of one or more data characters at the start of a packet which define the
route to be taken across a SpaceWire network from source to destination
3.2.83 physical layer
protocol layer which specifies the cables, connectors, cable assemblies, line
drivers and line receivers
3.2.84 port
SpaceWire interface or FIFO interface comprising an input port and an output
port
3.2.85 port reset
reset signal that resets a single SpaceWire port
3.2.86 receive error
error detected when receiving a symbol
NOTE This is a parity error or invalid code error
3.2.87 receive FIFO
FIFO memory which stores received N-Chars until they can be read by the
application via the SpaceWire port interface
3.2.88 receiver
circuit that receives signals from the line receiver and decodes those signals
into a stream of characters
3.2.89 receiver ground
ground at the 0V pin or pins of the receiver differential inputs
NOTE If the driver has one 0V for signals such as TTL
or CMOS, and a separate 0V for the differential
inputs, the receiver ground is the 0V for the
differential inputs. The receiver ground is a
plane or planes which provide controlled
impedance for the receiver's differential pairs.
3.2.90 reset
power on reset, other hardware reset or software commanded reset
3.2.91 rise time
time during which a rising signal voltage is within the range of 20 % to 80 % of
the difference between the two steady state values
3.2.92 router
routing switch
NOTE The term “router” is used because of the
heritage of SpaceWire which is based on
IEEE1355-1995 which is in turn based on earlier
work on Transputer technology. This work
predated the Internet and the use of the term
“router” to mean a device that determines the
route to a destination as opposed to a “switch”
that switches a packet to an output port based
on an address. In SpaceWire the term “router”
is used to mean a routing switch. This is widely
understood terminology in the SpaceWire
community.
3.2.93 routing switch
switch matrix connected to one or more SpaceWire ports, a configuration port
and a local broadcast code register, which optionally broadcasts broadcast
codes and which switches packets from one port to one or more other ports
where the destination address of each packet is used by the routing switch to
determine which port the packet is forwarded through
3.2.94 routing table
table in a routing switch which is indexed by the leading data character of the
packet to look-up the output port for forwarding a packet through
3.2.95 serialisation
transformation of a sequence of control or data symbols into a serial bit stream
3.2.96 signal
measurable quantity that varies with time and propagates along a transmission
medium to transfer information across that medium
3.2.97 skew
difference in time between the expected position of the rising or falling edge of
a signal and the actual position of that signal
3.2.98 source
originator of a packet, signal or other form of information
3.2.99 source node
node that is the source of one or more SpaceWire packets
3.2.100 SpaceWire interface
interface comprising a transmitter for sending information across a SpaceWire
link, and a receiver for receiving information from that SpaceWire link
3.2.101 SpaceWire network
two or more nodes connected together via one or more links and zero or more
routing switches
NOTE A point-to-point link between two nodes is
therefore regarded as a network.
3.2.102 SpaceWire node
node
3.2.103 SpaceWire port
port which has a SpaceWire interface
3.2.104 switch matrix
non-blocking, worm-hole routing switch that switches a packet arriving at an
input port of a routing switch to the appropriate output port, or to several
output ports in case of multicasting
3.2.105 symbol
encoded data character, encoded control character or encoded control code
3.2.106 time-code
code used to distribute synchronisation information over a SpaceWire network
3.2.107 time-code master
host application on a node that is responsible for periodically sending out time-
codes which are broadcast across the SpaceWire network
3.2.108 time-code master node
node on which the time-code master resides and which when requested by a
time-code master sends time-codes out of one or more end-points
3.2.109 time-code register
register in a node or routing switch that holds the value of the last time-code
received
3.2.110 time-code value
six bits of information contained in a time-code
3.2.111 transmission medium
medium over which data is transferred e.g. screened twisted-pair wires
3.2.112 transmit FIFO
FIFO memory which stores N-Chars until they can be sent across the link
3.2.113 transmitter
circuit that encodes the characters being sent across a link, serialises them,
data-strobe encodes them and passes the resulting data and strobe signals to
line drivers
3.2.114 unit
entity, like an instrument, processor or mass memory, which contains zero or
more nodes and zero or more routing switches, and which contains at least one
node or one routing switch
3.3 Abbreviated terms
The following abbreviations are defined and used within this standard:
Abbreviation Meaning
AWG
American Wire Gauge
BC
broadcast code
BER
bit error rate
DC
direct current
DS
Data-Strobe
ECSS
European Cooperation for Space Standardization
EEP
error end of packet
EOP
end of packet
ESA
European Space Agency
ESC
escape character
ESCC
European Space Components Coordination
FCT
flow control token
FIFO
first in first out
ID
identifier
IID
Interrupt identifier
LS
least-significant
LSB
least significant bit
LVDS
low voltage differential signalling
LVTTL
low voltage transistor-transistor logic
Mbps
Megabits per second
MS
most-significant
MSB
most-significant bit
PCB
printed circuit board
PSELFEXT
Power Sum Equal Level Far-End Cross-Talk
PSNEXT
Power Sum Near End Cross-Talk
RX
receive
SpW
SpaceWire
TDR
time domain reflectometer
TX
transmit
UML
Unified Modelling Language
3.4 Conventions
3.4.1 Numbers
In this document hexadecimal numbers are written with the prefix 0x, for
example 0x34 and 0xDF15.
Binary numbers are written with the prefix 0b, for example 0b01001100 and
0b01.
Decimal numbers have no prefix.
3.4.2 Differential signals
The two signals making up a differential pair are given the suffixes + and – to
indicate the positive and negative components of the differential signal,
respectively.
The SpaceWire differential signals are referred to as D+, D- and S+, S- for Data
and Strobe, respectively. When considering the driven end of a SpaceWire link,
these signals are designated Dout+, Dout- and Sout+, Sout- for Data and Strobe,
respectively. Similarly, the signals at the input end of a SpaceWire link are
Din+, Din- and Sin+, Sin-.
3.4.3 Order of sending bits in symbols
The first bit of a data symbol or control symbol to be sent is the parity bit.
The data bits of a data symbol are sent least significant bit first.
An arrow is added to relevant diagrams to illustrate the direction that the data
moves, and which bit is sent first as shown in Figure 3-1.
Arrow indicates direction in which data bits are sen
Parity bit is the first bit to be sent
P 0 D0 D1 D2 D3 D4 D5 D6 D7
LSB MSB
Data
Data-control flag
Parity bit
Figure 3-1: Convention for first bit to be sent
3.4.
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