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Microchip Technology Inc.

WebSeminar: November 19, 2003

Design considerations when adding CANbus

to your SystemPage 1

2003 Microchip Technology Incorporated. All Rights Reserved. Design considerations when adding CANbus to your System 1

Design considerations

when adding CANbus

to your System

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Overview

G Brief Introduction to ControllerArea Network(CAN)

G Design Considerations When Connectingto CAN

G Summary

G Microchip Product Offering

G References

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Brief Introduction to CAN

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CAN Introduction

Node 2Node 1 Node n

R Rmsg

Introduced in 1996 by Bosch

- Standardized by ISO 11898

Control is distributed across the

network

Message based system

- Messages are broadcast- All receivers ACK valid messages

- Receivers filter out unwantedmessages

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Message Format

S

O

F

Identifier

R

T

R

I

D

E

r DLC Data CRC

A

C

K

EOF IFS

Arbitration

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CAN Layers

Application

Network

CAN

Physical

Node specific application

HLP such as DeviceNet, J1939,

CANopen, CANKingdom,

Proprietary, etc.

CAN layer

Physical medium, transceiver,

wires, connectors, etc.

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Design Considerations WhenConnecting to CAN

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Some Considerations

G Adding CAN to an existing design, or to anew design?

G HLP requirements?

G Non-proprietary: J1939, CANopen, DeviceNet,etc.

G Proprietary: specialized HLP for specificsystem

G Node complexity?

G Simple low cost sensor, high-end complexdemanding node, etc.

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CAN Nodes

XCVR

MCU

CAN

XCVR

CAN I/O

Expander

XCVR

MCU

CAN

Integrated

CAN

Stand-alone

CAN

Smart serial

linked I/O

e.g., MCP2551

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Integrated Solution

XCVR

MCU

CAN

Two chip solution

Fast access to the

CAN peripheral

MCU may not fit

the application

May be cost

prohibitive

PROS CONS

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Stand-Alone CAN

XCVR

MCU

CANMCP2515

Choose best processor

for the application

Versatile:

Easily add CAN to

existing applications

Low cost CANperipheral

SPIPROS

e.g., PICmicro MCU

or dsPIC digital signal

controller

CONS

External interface

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Simple Sensor Node

XCVR

MCP2515

Small 8-bit MCU

A/D I/O

SPI Versatile:


for the application

Easily add CAN to



PROS

Simple sensor

CONS

External interface

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Moderate Complexity Node

XCVR

MCP2515

Complex

8-bit MCU

A/D I/O

PWM

I/OA/D

A/D

SPI Versatile:


for the application

Easily add CAN to



PROS

Simple sensorMedium complexity

CONS

External interface

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High Complexity Node

XCVR

MCP2515

32-bit MCUDSP

ASIC

A/D I/O

PWM

I/OA/D

A/D

PWM

PWM

A/D

A/D

SPI Versatile:


for the application

Easily add CAN to



PROS

Simple sensorMedium complexityHigh complexity

CONS

External interface

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Can I/O Expander

XCVR

CAN I/O

Expander

e.g. MCP250xx

Provides I/O

expansion for a CANnetwork

Smart sensor node

No MCU interface

Peripherals:

GPIO, A/D, PWM

Automatic message

transmission

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Can I/O Expander

XCVR

CAN I/O

Expander

e.g. MCP250xx

One chip solution

No MCU firmware

to write or debug

Low cost, simple

sensor applications

Ideal for proprietary

HLPs

PROS CONS

Less flexibility with

non-proprietary HLPs

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Summary

G CAN is a robust data communicationsprotocol which is suitable for:

G Simple sensor and display applications

G Distributing control across the network

G System critical applications in automotive andindustrial industries.

G Etc.

G Knowing the node and/or systemrequirements can help determine the bestsolution

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Microchips CAN Products

G MCP2515 Stand-alone CAN controllerG MCP250xx CAN I/O Expander (four devices)

G MCP2551 CAN Transceiver

G PIC18CXX8 (two devices)

G PIC18FXX8 (four devices)

G PIC18FX680 and PIC18FX585 ECAN (four devices)

G dsPIC30F601X 16-bit DSC with CAN

Future Devices:

G PIC18F2680/4680 and PIC18F2585/4585 ECAN

G dsPIC30F401X

G dsPIC30F501X

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References

G Application Notes

G ADN004, Ease into the Flexible CANbus Network

G AN713,An introduction to the CAN protocol that discusses thebasics and key features.

G AN212, Smart Sensor CAN Node using the MCP2510 andPIC16F876

G AN215,A Simple CAN Node using the MCP2510 and PIC12C67X

G AN228,A CAN Physical Layer Discussion

G AN754, Understanding Microchips CAN Module Bit Timing

G AN815, Understanding the MCP250xx Devices

G AN816, A CAN System Using Multiple MCP25050 CAN I/O

ExpandersG AN872, Upgrading from the MCP2510 to the MCP2515

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Design considerations when adding CANbusPage 20

2003 M icrochip Technology Incorporated. All Rights Reserved. Design considerations when adding CANbus to your System 20

WebSeminar:November 19, 2003

Design considerationswhen adding CANbus to

your System

canbus web

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