FlexCAN
30-3
Freescale Semiconductor
MCF52235 ColdFire® Integrated Microcontroller Reference Manual, Rev. 6
30.1.2
Features
Following are the main features of the FlexCAN module:
•
Full implementation of the CAN protocol specification version 2.0B
— Standard data and remote frames (up to 109 bits long)
— Extended data and remote frames (up to 127 bits long)
— 0–8 bytes data length
— Programmable bit rate up to 1 Mbps
— Content-related addressing
•
Up to 16 flexible message buffers of zero to eight bytes data length, each configurable as Rx or Tx,
all supporting standard and extended messages
•
Listen-only mode capability
•
Three programmable mask registers: global (for MBs 0–13), special for MB14, and special for
MB15
•
Programmable transmission priority scheme: lowest ID or lowest buffer number
•
Time stamp based on 16-bit, free-running timer
•
Global network time, synchronized by a specific message
•
Maskable interrupts
•
Independent of the transmission medium (an external transceiver is assumed)
•
Open network architecture
•
Multimaster bus
•
High immunity to EMI
•
Short latency time due to an arbitration scheme for high-priority messages
30.1.3
Modes of Operation
30.1.3.1
Normal Mode
In normal mode, the module operates receiving and/or transmitting message frames, errors are managed
normally, and all the CAN protocol functions are enabled. User and supervisor modes differ in the access
to some restricted control registers.
30.1.3.2
Freeze Mode
Freeze mode is entered by setting:
•
CANMCR[FRZ], and
•
CANMCR[HALT], or by asserting the BKPT signal.
After entry into freeze mode is requested, the FlexCAN waits until an intermission or idle condition exists
on the CAN bus, or until the FlexCAN enters the error passive or bus off state. After one of these
conditions exists, the FlexCAN waits for the completion of all internal activity such as arbitration,
matching, move-in, and move-out. When this happens, the following events occur:
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:MCF52234CVM60,
MCF52235CVM60
