MPC563XM Reference Manual, Rev. 1
Freescale Semiconductor
1297
Preliminary—Subject to Change Without Notice
28.4.4.13 Rx Individual Mask Registers (RXIMR0
–
RXIMR63)
These registers are used as acceptance masks for ID filtering in Rx MBs and the FIFO. If the FIFO is not
enabled, one mask register is provided for each available Message Buffer, providing ID masking capability
on a per Message Buffer basis. When the FIFO is enabled (FEN bit in MCR is set), the first 8 Mask
Registers apply to the 8 elements of the FIFO filter table (on a one-to-one correspondence), while the rest
of the registers apply to the regular MBs, starting from MB8.
The Individual Rx Mask Registers are implemented in RAM, so they are not affected by reset and must be
explicitly initialized prior to any reception. Furthermore, they can only be accessed by the CPU while the
module is in Freeze Mode. Out of Freeze Mode, write accesses are blocked and read accesses will return
“all zeros”. Furthermore, if the BCC bit in the MCR Register is negated, any read or write operation to
these registers results in access error.
NOTE
The individual Rx Mask per Message Buffer feature may not be available in
low cost MCUs. Please consult the specific MCU documentation to find out
if this feature is supported. If not supported, the RXGMASK, RX14MASK
and RX15MASK registers are available, regardless of the value of the BCC
bit.
Figure 28-15. Rx Individual Mask Registers (RXIMR0 - RXIMR63)
MI31–MI0 — Mask Bits
For normal Rx MBs, the mask bits affect the ID filter programmed on the MB. For the Rx FIFO, the
mask bits affect all bits programmed in the filter table (ID, IDE, RTR).
1 = The corresponding bit in the filter is checked against the one received
0 = the corresponding bit in the filter is “don’t care”
28.5
Functional Description
28.5.1
Overview
The FlexCAN module is a CAN protocol engine with a very flexible mailbox system for transmitting and
receiving CAN frames. The mailbox system is composed by a set of up to 64 Message Buffers (MB) that
store configuration and control data, time stamp, message ID and data (see
). The memory corresponding to the first 8 MBs can be configured to support a FIFO
Base + $0880–$097F
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
MI31 MI30 MI29 MI28 MI27 MI26 MI25 MI24 MI23 MI22 MI21 MI20 MI19 MI18 MI17 MI16
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
MI15 MI14 MI13 MI12 MI11 MI10
MI9
MI8
MI7
MI6
MI5
MI4
MI3
MI2
MI1
MI0