Welcome to Truck – Trailer Wireless

Connection,a master’s thesis presentation

People involved

Lecturer: Mikael Gunnarsson Examiner: Prof. Gerald Q. Maguire Jr. Adviser: Mattias Sjögren Opponent: Mats Sandberg

This presentation…

Scania Infotronics AB Control Area Networks Project goal Technologies (DECT, Bluetooth) Prototype Conclusions & future work Questions & discussion

Scania Infotronics AB

Subsidiary of Scania AB Provides IT- solutions for heavy vehicles, e.g.

the truck industry Located in Kista & founded in April 1999 Develops fleet management systems

Control Area Network”CAN”

Control Area Network, CAN

Standard for serial data communication. Differential transmission on a twisted

pair wire. ISO11992 & J1939 (differs in data transfer

rate and voltage levels)

CAN message format

Three major parts: ID, DLC, and data. CAN messages contains no dest. address. Source address is encapsulated in the ID. 8 bytes of data per message (max).

CAN gateways and the ID field A CAN gateway changes the source ID to

one that represents the vehicle from which it originated.

Cyclic message informs about location.

Project goal / problem statement

How to extend the CAN-bus into the trailer's ? Which wireless technology to use ? How to combine the chosen wireless technology

& the CAN protocol ?

Wireless link nodes

CAN - SAE J1939 CAN - ISO 11992 or SAE J1939

HandheldComputer

?

Problem Statement

A wireless gateway that can be placed anywhere in a road train.

Should be “stand alone”. Possible a serial link in parallel to CAN

DECT or

BlueTooth ?

DECT & BlueTooth

They are both wireless technologies supporting data and voice transfer.

European standards Data transfer rates ~300 – 700 kbps Built to deal with interference

DECT BlueTooth 1880 –1900 Mhz

2.45Mhz in North America.

Data transfer rate: 552kb/s in one direction or 288kb/s bidirectional

2.45Mhz

Spain, France, and Japan have narrower bandwidth.

Data transfer rate: 723kb/s in one direction or 433kb/s bidirectional

Interference avoidance: DECT 240 channels (10 carrier frequences * 24

timeslots in a frame) Continously checking the signal strength and

switch channel if a better is found.

Interference avoidance: BlueTooth 79 carrier frequences (23 in Spain, France,

and Japan). A frecuency hopping sequence is

pseudorandomly calculated upon the master’s internal clock.

Changes channel 1600 times per sec.

Networking

In DECT the devices are called ”fixed parts”, FP or ”portable parts”, PP. They have seperate rols in a connection.

The fixed part contains a list of portable parts that are allowed to connect.

In BlueTooth, all devices are identical ie. all devices can become master och slave in a connection.

It is possible to ask an anounymous device for its address over the air.

DECTor

BlueTooth?

Prototype development

Bluetooth module Bluetooth module

Fujitsu Microprocessor Fujitsu Microprocessor

RS232Interface Rs232

Interface

CAN bus CAN bus

Prototype development

Provides forwarding of Can messages. The gateway automatically adjusts to the

location in a road train. SourceID is changed according to ISO11992. Provides a RS232 serial interface in parallel

to the CAN bus. Connections are made and terminated via

Can messages. Software written i ANSI C.

Prototype developmentConnection establishment:

Forwarding CAN messagesFrom CAN : Through Bt-link:

Future Work

Hardware Bluetooth Product Qualification Standards

Discussion !