R8C-22_1 Datasheet, PDF (408/549 Pages) Renesas Technology Corp – MCU R8C FAMILY / R8C/2x SERIES

R8C/22 Group, R8C/23 Group
18. CAN Module
18.7 Acceptance Filtering Function and Masking Function
These functions serve the users to select and receive a facultative message. The C0GMR, C0LMAR, and
C0LMBR registers can perform masking to the standard or extended ID. The C0GMR register corresponds to slots
0 to 13, the C0LMAR register corresponds to slot 14, and the C0LMBR register corresponds to slot 15. When
acceptance filtering, the masking function is valid to a received 11 or 29 bit ID by the value set to the slot in the
C0IDR register. This function is used for receiving a certain range of IDs.
Figure 18.20 shows Correspondence of Mask Registers to Slots and Figure 18.21 shows the Acceptance Function.
C0GMR register
C0LMAR register
C0LMBR register
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 18.20 Correspondence of Mask Registers to Slots
ID of the received ID stored in
message
the slot
The value of the
mask register
Mask Bit Values
0 : ID (to which the received message
corresponds) match is handled as
“Do not care”.
1 : ID (to which the received message
corresponds) match is checked.
Acceptance
Signal
Figure 18.21 Acceptance Function
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.
When using the acceptance function, note the following points.
(1) If two or more slots are set the same ID and received a same message, the smallest slot number is valid.
(2) If slots 14 and 15 are set to receive all IDs in Basic mode, slots 14 and 15 can receive IDs which are not
received by slots 0 to 13.
Rev.2.00 Aug 20, 2008 Page 388 of 501
REJ09B0251-0200