DSPIC30F5013-20I Datasheet, PDF (107/220 Pages) Microchip Technology – 16-bit Digital Signal Controllers

17.0 CAN MODULE
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).
17.1 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 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 ver-
sions 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,
CAN 2.0A and CAN 2.0B
• Standard and extended data frames
• 0-8 bytes data length
• Programmable bit rate up to 1 Mbps
• 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
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 Input Capture module (IC2,
for both CAN1 and CAN2) for time-stamping and
network synchronization
• Low-power Sleep and Idle mode
dsPIC30F5011/5013
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.
17.2 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 desti-
nation node sends a remote frame with an identi-
fier that matches the identifier of the required data
frame. The appropriate 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
dominant bit during interframe space which is an
illegal condition. Second, due to internal condi-
tions, the node is not yet able to start reception of
the next message. A node may generate a maxi-
mum 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.
© 2011 Microchip Technology Inc.
DS70116J-page 107