may be useful for your engineering seminars and other technical presentations

1. CAN
Controller Area Network
BY-Ashutosh Bhardwaj
Roll no. -1213231054
E.C-A

2. INTRODUCTION
 CAN bus is a vehicle bus standard designed to allow
microcontroller and devices to communicate with each
other in vehicle.
 It is a message based protocol.
 It is a multi-master serial bus

3. COMPARING WITH OTHER BUSES
Bus Trnsfer type Transfer
rate(b/s)
Maximum
Length(m)
Number
of nodes
RS 232 Point to
Point
20k 15 1
RS 425 Network 35k 1200 32
I2C Master slave 100k 1 128
SOI Master slave 110k 1 any
CAN Network 1M 40 2032
USB Master slave 480M 5 126

4. HISTORY
 Introduced by Robert Bosch in 1986
 Developed for automotive applications
 Standardized in 1993 as ISO11898-1
 CAN Standards
1. CAN 2.0A
2. CAN 2.0B

5. CAN STANDARDS
1. CAN 2.0A
Standard CAN (ISO 11898)
11-bit Identifier
1 Mbps
2. CAN 2.0B
Extended CAN (ISO 11519)
29-bit Identifier
125 kbps

6. APPLICATIONS
 Automobiles
 Aerospace
 Maritime
 Industrial automachine
 Medical equipments

7. LAYERED STRUCTURE
 Application layer
 Object layer
 Transfer layer
 Physical layer

8. NETWORK COMPONENTS
 Physical Layer
1. Cable.
2. Connector
3. Transreciever
 CAN Controller
1. Part A
2. Part B(Passive)
3. Part B
 Software

9. CABLES
 Twisted Pair Cables are used to get higher speeds. The
Bit rate of the data transformation is high for short
distance and low for long distance.
Bus Length Bit Rate
40 Meters 1 Mbps
100 Meters 500 Kbps
200 Meters 250 Kbps
500 Meters 125Kbps
6 Meters 10Kbps

10. CAN CONTROLLERS
 Part A
 11-bit Identifier
 Above 2000 devices in the Network
 Part B Passive
 11-bit Identifier
 Tolerated 29-bit Identifier, but ignored
 Part B
 29-bit Identifier
 Above 5 million devices in the Network

11. WORKING PRINCIPLE
 Uses CSMA/CD+AMP (Arbitration on Message Priority).
 Data messages transmitted from any node
 Using identifier all nodes will check whether the
message is intended for it or not
 The identifier determines the priority of the message
 Low bits are always dominant

12. FRAME TYPES
 Data Frame
 Remote Frame
 Error Frame
 Overload Frame

13. MESSAGE (DATA) FRAME
Standard Data Frame
Extended Data Frame

14.  Start Of Frame:
Logic 0 indicates the beginning of a message frame.
 Arbitration Field:
11-bit identifier. Determines the priority of the message.
 Control Field:
6-bits. 2-bits are reserved for future use. 4-bit Data
Length Code (DLC) indicates the number of bytes in the
data field.

15.  Data Field:
0 to 8 Bytes of data
 CRC Field:
15-bits Cyclic Redundancy Check Code and 1-bit delimiter
 Acknowledgement Field:
2-bits. Slot bit (1) overwritten by dominant bit from other
nodes and delimiter bit (1).
 End Of Frame Field:
7-bits (1111111). Indicates the End of the data frame.
Following the End Of Field is the Intermission field consisting
of 3-bits (111) denotes the bus is recognized to be free.

16. REMOTE FRAME
The intended purpose of this frame is to ask for the transmission of the
corresponding data frame. It is also used implement a type of request-
response type of bus traffic management.

17. ERROR FRAME
 Consists of error flag (6-bits) and error delimiter (8-bits).
 Transmitted when a node detects a fault and will cause
all other nodes to detect a fault

18. OVERLOAD FRAME
 This frame is mentioned just for completeness of the
transaction.

19. ADVANTAGES
 High throughput under light loads
 Local and global prioritization possible

20. LIMITATION
 Unfair access - node with a high priority can "hog" the
network.
 Poor latency for low priority nodes.

21. CONCLUSION
 CAN is ideally suited in applications requiring a large
number of short messages with high reliability in rugged
operating environments. Because CAN is message based
and not address based, it is especially well suited when
data is needed by more than one location and system-
wide data consistency is mandatory.