M16C6NK Datasheet, PDF (257/404 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

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M16C/6N Group (M16C/6NK, M16C/6NM)
19. CAN Module
19.9 Acceptance Filtering Function and Masking Function
These functions serve the users to select and receive a facultative message. The CiGMR register (i = 0, 1),
the CiLMAR register, and the CiLMBR register can perform masking to the standard ID and the extended ID
of 29 bits. The CiGMR register corresponds to slots 0 to 13, the CiLMAR register corresponds to slot 14,
and the CiLMBR register corresponds to slot 15. The masking function becomes valid to 11 bits or 29 bits
of a received ID according to the value in the corresponding slot of the CiIDR register upon acceptance
filtering operation. When the masking function is employed, it is possible to receive a certain range of IDs.
Figure 19.16 shows correspondence of the mask registers and slots, Figure 19.17 shows the acceptance
function.
CiGMR register
CiLMAR register
CiLMBR register
i = 0, 1
Slot #0
Slot #1
Slot #2
Slot #3
Slot #4
Slot #5
Slot #6
Slot #7
Slot #8
Slot #9
Slot #10
Slot #11
Slot #12
Slot #13
Slot #14
Slot #15
Figure 19.16 Correspondence of Mask Registers to Slots
ID of the ID stored in
received message the slot
The value of the
mask register
Mask Bit Values
0: ID (to which the received message
corresponds) match is handled as
"Don’t care".
1: ID (to which the received message
corresponds) match is checked.
Acceptance Signal
Acceptance judge signal
0: The CAN module ignores the
current incoming message.
(Not stored in any slot)
1: The CAN module stores the
current incoming message in
a slot of which ID matches.
Figure 19.17 Acceptance Function
When using the acceptance function, note the following points.
(1) When one ID is defined in two slots, the one with a smaller number alone is valid.
(2) When it is configured that slots 14 and 15 receive all IDs with Basic CAN mode, slots 14 and 15 receive
all IDs which are not stored into slots 0 to 13.
Rev.2.00 Nov 28, 2005 page 239 of 378
REJ09B0124-0200