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Registers CiGMRk, CiLMARk, and CiLMBRk (i = 0, 1, k = 0 to 4) are used for acceptance filtering.
Using these registers, users are able to select which messages to receive.
The CiGMRk register determines whether IDs in the message slots 0 to 13 are checked or not. The CiLMARk
register determines whether ID in the message slot 14 is checked or not. The CiLMBRk register determines
whether ID in the message slot 15 is checked or not.
When the bit in registers CiGMRk, CiLMARk, and CiLMBRk is set to 0, the corresponding bit (ID bit) in
the CANi message slot j’s (j = 0 to 15) standard ID0, standard ID1, and extended ID0 to extended ID2 is
masked in acceptance filtering. (The corresponding bit is assumed to have a matching ID.)
When the bit in registers CiGMRk, CiLMARk, and CiLMBRk is set to 1, the corresponding ID bit is
compared with a received ID in acceptance filtering. When the received ID matches the ID set in the
message slot j, the receive data is stored into the message slot having the matched ID.
NOTES:
1. Change the CiGMRk register while none of the message slots 0 to 13 has a receive request.
2. Change the CiLMARk register while the message slot 14 has no receive request.
3. Change the CiLMBRk register while the message slot 15 has no receive request.
4. When there are two or more receive message slots which have the matched ID with the received message,
the received message is stored into the smallest-numbered message slot.
acceptance filtering.
Figure 22.28
Individual Mask Register and Message Slot
Figure 22.29
Acceptance Filtering
Message slot 0
to
Message slot 13
i = 0, 1
k = 0 to 4
Message slot 14
Message slot 15
CiGMRk register
CiLMARk register
CiLMBRk register
Receive message ID
ID set in the
message slot
CiGMR register
CiLMAR register
CiLMBR register
Value of the mask bit
0: Whether a receive message ID is matched
is handled as "don't care" (or masked)
1: Whether a receive message ID is matched
is verified
Acceptance verify signal
0: Receive message is ignored
(Message is stored into no message slot)
1: Receive message is stored into a
message slot having a matched ID
Acceptance verify signal
For Standard ID
Standard ID0
Standard ID1
Standard ID10
SID0
SID0M
SID1M
SID10M
SID1
SID10