DSPIC33FJ128GP304-I/ML View Datasheet(PDF) - Microchip Technology
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DSPIC33FJ128GP304-I/ML Datasheet PDF : 402 Pages
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dsPIC33FJ32GP302/304, dsPIC33FJ64GPX02/X04, AND dsPIC33FJ128GPX02/X04
19.0 ENHANCED CAN (ECAN™)
MODULE
Note 1: This data sheet summarizes the features
of the dsPIC33FJ32GP302/304,
dsPIC33FJ64GPX02/X04,
and
dsPIC33FJ128GPX02/X04 families of
devices. It is not intended to be a compre-
hensive reference source. To comple-
ment the information in this data sheet,
refer to “Section 21. Enhanced Control-
ler Area Network (ECAN™)” (DS70185)
of the “dsPIC33F/PIC24H Family Refer-
ence Manual”, which is available from the
Microchip website (www.microchip.com).
2: Some registers and associated bits
described in this section may not be avail-
able on all devices. Refer to Section 4.0
“Memory Organization” in this data
sheet for device-specific register and bit
information.
19.1 Overview
The Enhanced Controller Area Network (ECAN™)
module is a serial interface, useful for communicating
with other CAN modules or microcontroller devices.
This interface/protocol was designed to allow commu-
nications within noisy environments. The
dsPIC33FJ32GP302/304, dsPIC33FJ64GPX02/X04,
and dsPIC33FJ128GPX02/X04 devices contain up to
two ECAN modules.
The ECAN module is a communication controller imple-
menting the CAN 2.0 A/B protocol, as defined in the
BOSCH CAN specification. The module supports
CAN 1.2, CAN 2.0A, CAN 2.0B Passive and CAN 2.0B
Active versions of the protocol. The module implementa-
tion is a full CAN system. The CAN specification is not
covered within this data sheet. The reader can 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
• Automatic response to remote transmission
requests
• Up to eight transmit buffers with application speci-
fied prioritization and abort capability (each buffer
can contain up to 8 bytes of data)
• Up to 32 receive buffers (each buffer can contain
up to 8 bytes of data)
• Up to 16 full (standard/extended identifier)
acceptance filters
• Three full acceptance filter masks
• DeviceNet™ addressing support
• 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 CAN1) 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 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 Frame Types
The ECAN 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 iden-
tifier that matches the identifier of the required data
frame. The appropriate data source node sends 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 two 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 can 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.
2009 Microchip Technology Inc.
Preliminary
DS70292D-page 221
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