controller area network protocol

DESIGN AND IMPLIMENTATION OF CONTROLLER AREA NETWORK

PROTOCOL

Contents• Introduction

• Aim

• History

• CAN Principle

• Block diagram

• Transmitter

• Receiver

• Buffer

• Software and hardware required

• Results

• Advantages

• Applications

• Conclusion

Introduction• The Controller Area Network (CAN) is a serial communication protocol,

which efficiently supports distributed real time control with high level of

security.

• The CAN protocol is an ISO standard (ISO 11898), which includes a

physical layer and a data-link layer of the OSI model.

• Of these two layers, Data link layer is the only layer, which can be

designed and implemented using VLSI technology.

• It can transmit from 0 to 8 bytes of information.

• The maximum data rate is 1 Mbs

Aim

• To understand and develop the architecture of Controller Area Network

which is used in data link layer of the OSI model and to simulate and

synthesize it at its functional level.

History

• In February of 1986, Robeggrt Bosch GmbH introduced the serial bus

system Controller Area Network (CAN) at the Society of Automotive

Engineers (SAE) congress.

• It was introduced as ‘Automotive Serial Controller Area Network’.

• Later Uwe Kiencke, Siegfried Dais and Martin Litschel introduced the

multi-master network protocol.

CAN Principle• Data messages transmitted from any node on a CAN bus do not contain

addresses of either the transmitting node, or of any intended receiving

node. Instead, an identifier that is unique throughout the network labels

the content of the message.

• All other nodes on the network receive the message and each performs

an acceptance test on the identifier to determine if the message, and thus

its content, is relevant to that particular node.

• If the message is relevant, it will be processed; otherwise it is ignored

Block diagram

Transmitter• It has 7 states they are:1. DLC state2. Packet state3. Shift state4. CRC state5. Bit stuffing state6. Status state7. Transmission state

Transmitter state diagram

Transmitter control unit Data Length Counter

Mixer

serial

Parallel to serial CRC Generator Bit stuffing

Status register Data transmission

Receiver

• It has seven states they are

1.shift state2.de-stuffing state3.status state4.serial shift state5.CRC state6.Error message state7.FIFO state

Receiver state diagram

Reciever control unit Serial to parallel

Destuffing

Status registerParallel to serial

CRC Checker Error management logic

Buffer

• Transmit buffer and Receive buffers acts as interface to the micro

controller and the respective blocks (transmitter and receiver

respectively).

• Transmit buffer consists of two types of data namely arbitration of the

channel and user information, it takes the input from the micro

controller.

• Receive buffer consists of the user information and its output will be

taken by micro controller.

Software and Hardware required

• Software:

Xilinx ISE 14.7

• Hardware:

FPGA(SPARTAN-6)

Simulation results

• Simulation output for CAN top module

• Simulation output for Receiver

• Simulation output for transmitter

FPGA output• FPGA output for receiver

• FPGA output for transmiter

Advantages

• Low-cost, lightweight network

• Broadcast communication

• Priority

• Error capabilities

Applications

• Can was first created for automotive use, so its most common

application is in-vehicle electronic networking.

• Railway applications such as streetcars, trams, undergrounds and long-

distance trains incorporate can.

• You can find can on different levels of the multiple networks.

• Can also has applications in aircraft with flight-state sensors, navigation

systems, and research pcs in the cockpit.

Conclusion

• All architectures are developed using Behavioral modeling in VHDL and

the functionality check for each block is performed successfully.

• The entire module in the architecture has been synthesized and

implemented using XILINX ISE 14.7 software.

• The required bitmap file used for JTAG programming of the device is

obtained successfully.