Microchip Technology dsPIC30F6010 Datasheet Download

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2004 Microchip Technology Inc.

Advance Information

DS70119B-page 115

dsPIC30F6010

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. The dsPIC30F6010 has 2 CAN
modules.

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, CAN2.0B 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)

• 6 full (standard/extended identifier) acceptance

filters, 2 associated with the high priority receive
buffer, and 4 associated with the low priority
receive buffer

• 2 full acceptance filter masks, one each associ-

ated 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 trans-
mitted by first loading the appropriate data registers.
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 a 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 2 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 2 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.