DSPIC30F4012 Microchip Technology Inc., DSPIC30F4012 Datasheet - Page 125

• Manufacturer Part Number: DSPIC30F4012
• Description: Dspic30f4011/4012 Enhanced Flash 16-bit Digital Signal Controller
• Manufacturer: Microchip Technology Inc.

19.0
19.1
The Controller Area Network (CAN) module is a serial
interface, useful for communicating with other CAN
modules or digital signal controller devices. This inter-
face/protocol was designed to allow communications
within noisy environments. The dsPIC30F4011/4012
devices have 1 CAN module.
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 implementation 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,
• 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
• 6 full (standard/extended identifier), acceptance
• 2 full, acceptance filter masks, one each associated
• Three transmit buffers with application specified
• Programmable wake-up functionality with
• Programmable Loopback mode supports self-test
• Signaling via interrupt capabilities for all CAN
• Programmable clock source
• Programmable link to input capture module (IC2,
• Low-power Sleep and Idle mode
© 2007 Microchip Technology Inc.
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, register 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 “dsPIC30F/
33F Programmer’s Reference Manual” (DS70157).
CAN 2.0A and CAN 2.0B
received message storage buffers (each buffer
may contain up to 8 bytes of data)
filters, 2 associated with the high priority receive
buffer and 4 associated with the low priority
receive buffer
with the high and low priority receive buffers
prioritization and abort capability (each buffer may
contain up to 8 bytes of data)
integrated low-pass filter
operation
receiver and transmitter error states
for both CAN1 and CAN2) for time-stamping and
network synchronization
CAN MODULE
Overview
The CAN bus module consists of a protocol engine and
message buffering/control. The CAN protocol engine
handles all functions for receiving and transmitting
messages on the CAN bus. Messages are transmitted
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
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:
19.2.1
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).
19.2.2
An extended data frame is similar to a standard data
frame but includes an extended identifier as well.
19.2.3
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.
19.2.4
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.
19.2.5
An overload frame can be generated by a node as a
result of 2 conditions. First, the node detects a domi-
nant bit during interframe 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.
19.2.6
Interframe space separates a proceeding frame (of
whatever type) from a following data or remote frame.
dsPIC30F4011/4012
Frame Types
STANDARD DATA FRAME
EXTENDED DATA FRAME
REMOTE FRAME
ERROR FRAME
OVERLOAD FRAME
INTERFRAME SPACE
DS70135E-page 123