DSPIC30F5015 datasheet(129/234 Pages) MICROCHIP

129 / 234 page

DS70149E-page 129

dsPIC30F5015/5016

19.0

CAN MODULE

19.1

Overview

The Controller Area Network (CAN) module is a serial

interface, useful for communicating with other CAN

modules or microcontroller devices. This interface/

protocol was designed to allow communications within

noisy

environments.

Only

one

CAN

module

available.

The CAN module is a communication controller imple-

menting the CAN 2.0 A/B protocol, as defined in the

BOSCH

specification.

The

module

will

support

CAN 1.2, CAN 2.0A, CAN 2.0B Passive and CAN 2.0B

Active versions of the protocol. The module implemen-

tation is a full CAN system. The CAN specification is

not covered within this data sheet. The reader may

refer to the BOSCH CAN specification for further

details.

The module features are as follows:

• Implementation of the CAN protocol CAN 1.2,

CAN 2.0A and CAN 2.0B

• Standard and extended data frames

• 0-8 bytes data length

• Programmable bit rate up to 1 Mbit/sec

• Support for remote frames

• Double-buffered receiver with two prioritized

received message storage buffers (each buffer

may contain up to 8 bytes of data)

• Six full (standard/extended identifier) acceptance

filters, two associated with the high priority

receive buffer, and four associated with the low

priority receive buffer

• Two full acceptance filter masks, one each

associated with the high and low priority receive

buffers

• Three transmit buffers with application specified

prioritization and abort capability (each buffer may

contain up to 8 bytes of data)

• Programmable wake-up functionality with

integrated low pass filter

• Programmable Loopback mode supports self-test

operation

• Signaling via interrupt capabilities for all CAN

receiver and transmitter error states

• Programmable clock source

• Programmable link to timer module for

time-stamping and network synchronization

• Low-power Sleep and Idle mode

The CAN bus module consists of a protocol engine,

and message buffering/control. The CAN protocol

engine handles all functions for receiving and transmit-

ting messages on the CAN bus. Messages are

transmitted by first loading the appropriate data regis-

ters. Status and errors can be checked by reading the

appropriate registers. Any message detected on the

CAN bus is checked for errors and then matched

against filters to see if it should be received and stored

in one of the receive registers.

19.2

Frame Types

The CAN module transmits various types of frames,

which include data messages or remote transmission

requests initiated by the user as other frames that are

automatically generated for control purposes. The

following frame types are supported:

• Standard Data Frame

A Standard Data Frame is generated by a node when

the node wishes to transmit data. It includes an 11-bit

Standard Identifier (SID) but not an 18-bit Extended

Identifier (EID).

• Extended Data Frame

An Extended Data Frame is similar to a Standard Data

Frame, but includes an Extended Identifier as well.

• Remote Frame

It is possible for a destination node to request the data

from the source. For this purpose, the destination node

sends a Remote Frame with an identifier that matches

the identifier of the required Data Frame. The appropri-

ate data source node will then send a Data Frame as a

response to this remote request.

• Error Frame

An Error Frame is generated by any node that detects

a bus error. An error frame consists of two fields: an

Error Flag field and an Error Delimiter field.

• Overload Frame

An Overload Frame can be generated by a node as a

result of 2 conditions. First, the node detects a domi-

nant bit during lnterframe Space, which is an illegal

condition. Second, due to internal conditions, the node

is not yet able to start reception of the next message. A

node may generate a maximum of two sequential

Overload Frames to delay the start of the next

message.

• Interframe Space

Interframe Space separates a proceeding frame (of

whatever type) from a following Data or Remote

Frame.

Note:

This data sheet summarizes features of

this group of dsPIC30F devices and is not

intended to be a complete reference

source. For more information on the CPU,

peripherals,

descriptions

and

general device functionality, refer to the

“dsPIC30F Family Reference Manual”

(DS70046). For more information on the

device instruction set and programming,

refer to the “16-bit MCU and DSC

Programmer’s

Reference

Manual”

(DS70157).

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