LOW COST AUTOMOTIVE NETWORKS Local Interconnect Network (LIN) TTP/A 1 J. Kaiser, IVS-EOS
Cost-Performance Trade-off! 2 J. Kaiser, IVS-EOS
LIN (Local Interconnect Network)! LIN Specification Package, Revision 1.2, Nov. 17, 2000! 3 J. Kaiser, IVS-EOS
Properties of LIN. single-master / multiple-slave concept. low cost silicon implementation based on common UART/SCI interface hardware, an equivalent in software, or as pure state machine.. self synchronization without quartz or ceramics resonator in the slave nodes. guarantee of latency times for signal transmission. low cost single-wire implementation. speed up to 20kbit/s. 4 J. Kaiser, IVS-EOS
Master-Slave communication in LIN! header! response! t! Interframe Gap! Header:! - serves for the synchronisation of slaves! - specifies the sequence and length of the fields in the data frame! 5 J. Kaiser, IVS-EOS
LIN (Local Interconnect Network)! LIN Specification Package, Revision 1.2, Nov. 17, 2000! time dependent master/slave protocol! only 1 slave! is allowed to! respond!! But all slaves receive! the response.! 6 J. Kaiser, IVS-EOS
LIN Specification Package, Revision 1.2, Nov. 17, 2000! 7 J. Kaiser, IVS-EOS
LIN Bit Coding Byte-oriented 8N1 (8 Databits, 1 Stop-bit) 8 J. Kaiser, IVS-EOS
LIN Specification Package, Revision 1.2, Nov. 17, 2000! Synch. Feld! 0x55! 9 J. Kaiser, IVS-EOS
LIN Specification Package, Revision 1.2, Nov. 17, 2000! 64 identifiers!! divided in 4 groups of! length: 2,4, and 8 bytes!! An ID identifies the! content of a message,! not the sender or receiver!! Slaves can be added or removed without changing any software in the other slaves.! 10 J. Kaiser, IVS-EOS
LIN Identifier Interpretation! identifier (4)! length field! check field! content-based addressing! 0 1 2 3 4 5 P0 P1! max. 8 Byte response frame! 2 byte! 16 x! 2 byte! 4 byte! 8 byte! reserved IDs:!Master request Frame (0x3C), Slave Response Frame (0x3D)!!!Extended Frames (User 0x3E, Reserved 0x3F)! 11 J. Kaiser, IVS-EOS
LIN Master Request Frame! Download of data to the slave.! Request of data from the slave.!! Multiple 8 byte fields possible!! Slave address is part of the command fields.! 12 J. Kaiser, IVS-EOS
LIN Extended Frame! slaves, whiche are not addressed (interested resp.)! wait until the next SyncBreak!! 13 J. Kaiser, IVS-EOS
LIN ID format! identifier (4)! length field! check field! 0 1 2 3 4 5 P0 P1! 1 1 1 1 1 1 0 1! 0 1 2 3 4 5 P0 P1! ID# Hex P0 P1 1st digit 2nd digit dec hex #byte" 7 6 5 4 3 2 1 0" 60a 0x3C 0 0 0 0 1 1 1 1 0 0 60 0x3C 8" 61b 0x3D 1 0 0 1 1 1 1 1 0 1 125 0x7D 8" 62c 0x3E 1 1 1 1 1 1 1 1 1 0 254 0xFE 8" 63d 0x3F 0 1 1 0 1 1 1 1 1 1 191 0xBF 8! 0x3F à 0xBF! 14 J. Kaiser, IVS-EOS
LIN Identifier Interpretation! 15 J. Kaiser, IVS-EOS
Error detection capabilties of LIN:! Bit-Error (Master or slave task is sending, detection by Bit monitoring) Identifier-Parity-Error (Master and/or Slave) Checksum-Error (slave tasks receiving) Slave-Not-Responding-Error (slave task in master node is receiving) Inconsistent-Synch-Field-Error (sync out of specified bounds) Detected errors are flagged locally only 16 J. Kaiser, IVS-EOS
TTP/A (Time Triggered Protocol for SAE class A applica7ons) H. Kopetz, W. Elemenreich, C. Mack: A Comparison of LIN and TTP/A, Research report 4/2000, Ins7tut für Technische Informa7k, TU Wien OMG Standard: Smart Transducer Interfaces (Document number - ORBOS/ 2001-06-03, June 18, 2001 17 J. Kaiser, IVS-EOS
General Architecture 18 J. Kaiser, IVS-EOS
TTP/A - real 7me data - round: up to 64 byte - broadcast - managment and configura7on data - diagnos7c interface - point- to- point 3 different interfaces for slaves: - RMI : Real- Time message Interface - DMI: Diagnos7c message Interface - CMI: Configura7on Message Interface 19 J. Kaiser, IVS-EOS
master- slave dialogue fireworks frame data frame t Interframe Gap <master-slave ("fireworks"), file op and identifier, record number, logical node name, check byte> mul7 partner round fireworks frame data frames t Interframe Gap 20 J. Kaiser, IVS-EOS
Data centric communica1on model - real 7me frames contain data only! - all data is stored in the Interface File System (IFS). - addresses to data are specified as IFS addresses. - addresses are specified in the round descrip7on list (RODL), i.e. the 7me slot in which the message is transmi]ed is fixed according to the TT model. Mul7partner Round data data data Round Descrip7on List: RODL baf: byte aaer fireworks op: opera7on IFS: IFS- Adresse p: protec7on (checksum) baf baf.. baf op, IFS, p op, IFS, p.. op, IFS, p The RODL is also stored in the IFS and can be configured via the CMI. There are max. 8 RODLs. RODL# is transmi]ed with a Hamming Distance of 4 (high protec7on against failures). 21 J. Kaiser, IVS-EOS
Programming model for smart transducers in the IFS 22 J. Kaiser, IVS-EOS
The address space of the Interface File System IFS Address contains: < node, file, record, byte, checksum> 2 8 2 6 2 8 2 2 up to 256 nodes every node in the IFS supports: up to 64 files up to 256 records with 4 bytes each i.e. an address space of 2 16 bytes/node. and how to address the nodes? 23 J. Kaiser, IVS-EOS
Every Smart Transducer has a unique physical name (8 bytes) consis7ng of: - a node type name (series number) - a node name within series (serial number) During opera7on a node is addressed by a one- byte logical name that is unique within a cluster (i.e. up to 256 nodes/cluster). The assignment of a logical name to a node is called bap7zing and can be performed on- line. Low cost nodes can have preprogrammed logical names. During opera7on a node is addressed by: <Cluster Name, Node Name, File Name, Record Name> 24 J. Kaiser, IVS-EOS
General architecture of a TTP/A system global name of a data item: <cluster name, node name, file name, record name> externes System Master.............. Master Smart Transducers Cluster Cluster h]p://www.omg.org/docs/formal/03-01- 01.pdf 25 J. Kaiser, IVS-EOS
Integra7ng a TTP/A system in CORBA 26 J. Kaiser, IVS-EOS
LIN and TTP/A common properties and goals - Master/Slave protocols - low dependability requirements - free- runing low cost oscillators should be possible - physical Single- Wire- Network (asynch. serial interface) - low bandwidth requirements - low cost 27 J. Kaiser, IVS-EOS
Comparison LIN und TTP/A (response time and protocol efficiency) Kopetz, Elmenreich, Mack, TU Wien, 2000 protocol overhead response time 28 J. Kaiser, IVS-EOS