DRAFT
2019-01-28 Specification v1.0
Table of contents
1 Introduction . . . . . . . . . . . . 1
1.1 Document conventions . . . . . . . 1
1.2 Design principles . . . . . . . . . 1
1.3 Capabilities . . . . . . . . . . . 2
1.4 Maintenance of the standard data type
set . . . . . . . . . . . . . . 2
1.5 Referenced sources . . . . . . . . 2
2 Basic concepts . . . . . . . . . . . . 4
2.1 Main principles. . . . . . . . . . 4
2.1.1 Communication . . . . . . . . 4
2.1.2 Data types . . . . . . . . . 4
2.1.3 High-level functions . . . . . . . 6
2.2 Message publication . . . . . . . . 6
2.2.1 Anonymous message publication . . . 6
2.3 Service invocation . . . . . . . . . 6
3 Data structure description language . . . . 8
3.1 Architecture . . . . . . . . . . . 8
3.1.1 General principles . . . . . . . 8
3.1.2 Data types and namespaces . . . . . 8
3.1.3 File hierarchy . . . . . . . . . 9
3.2 Grammar . . . . . . . . . . . . 10
3.2.1 Formal definition. . . . . . . . 10
3.3 Data serialization . . . . . . . . . 12
3.3.1 General principles . . . . . . . 12
3.3.2 Scalar values . . . . . . . . . 13
3.3.3 Nested data structures . . . . . . 13
3.3.4 Fixed size arrays . . . . . . . . 13
3.3.5 Dynamic arrays . . . . . . . . 13
3.3.6 Unions . . . . . . . . . . 14
3.4 Data type compatibility and versioning . 14
3.4.1 Rationale . . . . . . . . . . 14
3.4.2 Bit compatibility . . . . . . . . 15
3.4.3 Semantic compatibility . . . . . . 17
3.4.4 Data type versioning . . . . . . . 17
3.5 Conventions and recommendations . . 20
4 Transport layer. . . . . . . . . . . . 21
4.1 Core concepts . . . . . . . . . . 21
4.1.1 Transfer . . . . . . . . . . 21
4.1.2 Message publication . . . . . . . 22
4.1.3 Service invocation . . . . . . . 22
4.1.4 Transfer priority . . . . . . . . 23
4.1.5 Transfer descriptor . . . . . . . 24
4.2 Transfer emission . . . . . . . . . 24
4.2.1 Transfer ID computation. . . . . . 24
4.2.2 Single frame transfers . . . . . . 25
4.2.3 Multi-frame transfers . . . . . . 25
4.2.4 Redundant interface support . . . . 27
4.3 Transfer reception . . . . . . . . . 28
4.3.1 Transfer ID comparison . . . . . . 28
4.3.2 State variables . . . . . . . . 28
4.3.3 State update in a redundant interface
configuration . . . . . . . . . 30
4.3.4 State update in a non-redundant inter-
face configuration . . . . . . . 32
4.4 CAN bus transport layer specification . . 33
4.4.1 CAN ID structure . . . . . . . . 33
4.4.2 CAN frame data . . . . . . . . 35
4.4.3 Software design considerations . . . . 37
5 Application layer . . . . . . . . . . . 40
5.1 Application-level conventions. . . . . 41
5.1.1 Identifier distribution . . . . . . 41
5.1.2 Coordinate frames . . . . . . . 41
5.1.3 Rotation representation . . . . . . 42
5.1.4 Matrix representation . . . . . . 42
5.1.5 Physical quantity representation . . . 43
5.2 Application-level functions. . . . . . 44
5.2.1 Node initialization . . . . . . . 44
5.2.2 Node heartbeat . . . . . . . . 44
5.2.3 Generic node information . . . . . 45
5.2.4 Bus data flow monitoring . . . . . 46
5.2.5 Network-wide time synchronization . . 46
5.2.6 Primitive types and physical quantities . . 47
5.2.7 Remote file system interface . . . . . 49
5.2.8 Generic node commands . . . . . 49
5.2.9 Node software update . . . . . . 49
5.2.10 Register interface. . . . . . . . 50
5.2.11 Diagnostics and event logging . . . . 50
5.2.12 Plug-and-play nodes . . . . . . . 50
5.2.13 Internet/LAN forwarding interface . . . 51
6 List of standard data types . . . . . . . . 52
6.1 uavcan.diagnostic . . . . . . . . . 55
6.1.1 Record . . . . . . . . . . 55
6.1.2 Severity . . . . . . . . . . 55
6.2 uavcan.file . . . . . . . . . . . 56
6.2.1 GetInfo . . . . . . . . . . 56
6.2.2 List . . . . . . . . . . . 56
6.2.3 Modify . . . . . . . . . . 57
6.2.4 Read . . . . . . . . . . . 57
6.2.5 Write . . . . . . . . . . . 58
6.2.6 Error . . . . . . . . . . . 58
6.2.7 Path . . . . . . . . . . . 58
6.3 uavcan.internet.udp . . . . . . . . 59
6.3.1 HandleIncomingPacket . . . . . . 59
6.3.2 OutgoingPacket . . . . . . . . 60
6.4 uavcan.node. . . . . . . . . . . 62
6.4.1 ExecuteCommand . . . . . . . 62
6.4.2 GetInfo . . . . . . . . . . 63
6.4.3 GetTransportStatistics . . . . . . 63
6.4.4 Heartbeat . . . . . . . . . . 64
6.4.5 ID . . . . . . . . . . . . 65
6.4.6 IOStatistics . . . . . . . . . 65
6.4.7 Version . . . . . . . . . . 65
6.5 uavcan.node.port . . . . . . . . . 65
6.5.1 GetInfo . . . . . . . . . . 65
6.5.2 GetStatistics . . . . . . . . . 66
6.5.3 List . . . . . . . . . . . 66
6.5.4 ID . . . . . . . . . . . . 67
6.5.5 ServiceID . . . . . . . . . . 67
6.5.6 SubjectID . . . . . . . . . . 67
6.6 uavcan.pnp . . . . . . . . . . . 68
6.6.1 NodeIDAllocationData . . . . . . 68
6.6.2 NodeIDAllocationDataMTU8 . . . . 70
6.7 uavcan.pnp.cluster . . . . . . . . 71
6.7.1 AppendEntries . . . . . . . . 71
6.7.2 Discovery . . . . . . . . . . 72
6.7.3 RequestVote . . . . . . . . . 72
6.7.4 Entry . . . . . . . . . . . 72
6.8 uavcan.register . . . . . . . . . . 74
6.8.1 Access. . . . . . . . . . . 74
6.8.2 List . . . . . . . . . . . 75
6.8.3 Name . . . . . . . . . . . 75
6.8.4 Value . . . . . . . . . . . 75
6.9 uavcan.time . . . . . . . . . . . 77
6.9.1 GetSynchronizationMasterInfo . . . . 77
6.9.2 Synchronization . . . . . . . . 77
6.9.3 SynchronizedAmbiguousTimestamp . . 79
6.9.4 SynchronizedTimestamp . . . . . 79
6.9.5 TimeSystem . . . . . . . . . 80
6.10 uavcan.primitive . . . . . . . . . 81
6.10.1 Empty . . . . . . . . . . . 81
6.10.2 String . . . . . . . . . . . 81
6.10.3 Unstructured . . . . . . . . . 81
6.11 uavcan.primitive.array . . . . . . . 81
6.11.1 Bit . . . . . . . . . . . . 81
6.11.2 Integer8 . . . . . . . . . . 81
6.11.3 Integer16 . . . . . . . . . . 82
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