SH7059 Datasheet, PDF (524/1042 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

17. Controller Area Network-II (HCAN-II)
17.3.4 Local Acceptance Filter Mask (LAFM)/Tx-Trigger Time (TTT)
This area is used as the local acceptance filter mask (LAFM) for receive boxes or as the Tx-trigger time (TTT) for transmit
boxes.
LAFM: When the MBC bits are set to 001, 010, 011, 100, and 101, this field becomes the LAFM field. The LAFM is
comprised of two 16-bit readable/writable areas. It allows a mailbox to accept more than one receive IDs.
Register
Name
Address
HCAN0
HCAN1
Data Bus
Access Size Field Name
15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
MBx[15], MBx[16] H'110+N•32 H'910+N•32
0
MBx[17], MBx[18] H'112+N•32 H'912+N•32
STDID[10:0]
EXTID[15:0]
0
0 EXTID[17:16]
16 bits
LAFM field
16 bits
[Legend] x/N: 0 to 31 (Indicates the mailbox number)
Figure 17.5 Acceptance Filter
If a bit is set in the LAFM, the corresponding bit of a received CAN ID is ignored when the HCAN searches a mailbox
with the matching CAN ID. If the bit is cleared, the corresponding bit of a received CAN ID must match the
STD_ID/EXT_ID set in the mailbox to be stored. The configuration of the LAFM is same as the message control in a
mailbox. If this function is not required, it must be filled with 0.
Notes: 1. When the LAFM is used, the HCAN starts to find a matching ID from mailbox 31 down to mailbox 0. As soon
as the HCAN finds one, it stops the search and stores the message into the mailbox. This means that a received
message can only be stored into one mailbox.
2. When a message is received and a matching mailbox is found, the whole message is stored into the mailbox.
This means that, if the LAFM is used, the STD_ID, RTR, IDE, and EXT_ID differ to the ones originally set as
they are updated with the STD_ID, RTR, IDE, and EXT_ID of the received message.
3. If the setting of the LAFM register that has already been set is changed, the HCAN should be set to halt mode
before changing the setting. Do not access the LAFM during operation.
4. Do not access the undefined addresses. Correct operation cannot be guaranteed.
LAFM Field:
Register Name Address
Bit
Bit Name
Description
MBx[15],
MBx[16]
H'110 + N • 32 15
⎯
Reserved
The write value should be 0. Values read out in the initial state
are not guaranteed.
14 to 4 STDID_LAFM Filter Mask Bits[10:0] for CAN Base ID[10:0]
[10:0]
0: Corresponding bit to CAN base ID set in mailbox 0 is valid
1: Corresponding bit to CAN base ID set in mailbox 0 is invalid
3, 2 ⎯
Reserved
The write value should be 0. Values read out in the initial state
are not guaranteed.
1, 0 EXTID_LAFM Filter Mask Bits[17:16] for CAN Extended ID[17:16]
[17:16]
0: Corresponding bit to extended CAN base ID is valid
1: Corresponding bit to extended CAN base ID is invalid
MBx[17],
MBx[18]
H'112 + N • 32 15 to 0 EXTID_LAFM Filter Mask Bits[15:0] for CAN Extended ID[15:0]
[15:0]
0: Corresponding bit to extended CAN base ID is valid
1: Corresponding bit to extended CAN base ID is invalid
Note: * x/N: 0 to 31 (Indicates the mailbox number)
Rev.3.00 Mar. 12, 2008 Page 434 of 948
REJ09B0177-0300