FlexCAN RM0046
546/936 Doc ID 16912 Rev 5
Control Register (CTRL)
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 BOFF_MSK, ERR_MSK, TWRN_MSK, RWRN_MSK and BOFF_REC bits, that can
be accessed at any time.
22–23
IDAM
ID Acceptance Mode
This 2-bit field identifies the format of the elements of the Rx FIFO filter table, as shown in
Ta bl e 27 4 . Note that all elements of the table are configured at the same time by this field (they are
all the same format). See Section 22.3.3, “Rx FIFO structure.
26–31
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 MB configuration. This field
should be changed only while the module is in Freeze Mode.
Maximum MBs in use = MAXMB + 1
Note: MAXMB has to be programmed with a value smaller or equal to the number of
available Message Buffers, otherwise FlexCAN will not transmit or receive frames.
Table 273. MCR field descriptions (continued)
Field Description
Table 274. 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.
Figure 266. Control Register (CTRL)
Address:
Base + 0x0004 Access: User read/write
0123456789101112131415
R
PRESDIV RJW PSEG1 PSEG2
W
Reset0000000000000000
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
R
BOFF
_MSK
ERR_
MSK
CLK_
SRC
LPB
TWRN
_MSK
RWRN
_MSK
00
SMP
BOFF
_REC
TSYN
LBUF
LOM PROPSEG
W
Reset0000000000000000
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