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FlexCAN Module
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
1407
32.4.5.2
Control Register (CR)
This register is defined for specific FlexCAN control features related to the CAN bus, such as bit-rate,
programmable sampling point within an Rx bit, Loop Back Mode, Listen Only Mode, Bus Off recovery
behavior and interrupt enabling (Bus-Off, Error, Warning). It also determines the Division Factor for the
clock prescaler. Most of the fields in this register should only be changed while the module is in Disable
Mode or in Freeze Mode. Exceptions are the BOFFMSK, ERRMSK, TWRNMSK, RWRNMSK and
BOFFREC bits, that can be accessed at any time.
IDAM
ID Acceptance Mode
This 2-bit field identifies the format of the elements of the Rx FIFO filter table, as shown in
. Note that all elements of the table are configured at the same time by this field (they
are all the same format). See
Section 32.4.4, Rx FIFO structure
.
MAXMB
Maximum Number of Message Buffers
This 6-bit field defines the maximum number of message buffers that will take part in the matching
and arbitration processes. The reset value (0x0F) is equivalent to 16 message buffer
configuration. This field should be changed only while the module is in Freeze Mode.
Maximum message buffers in use = MAXMB + 1.
Note:
MAXMB must be programmed with a value smaller or equal to the number of available
Message Buffers, otherwise FlexCAN can transmit and receive wrong messages.
Table 32-9. IDAM coding
IDAM
Format
Explanation
00
A
One full ID (standard or extended) per filter element
01
B
Two full standard IDs or two partial 14-bit extended IDs per filter element
10
C
Four partial 8-bit IDs (standard or extended) per filter element
11
D
All frames rejected
Table 32-8. Module Configuration Register (MCR) field descriptions
Field
Description
Summary of Contents for MPC5644A
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