SH7137 Datasheet, PDF (761/1160 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperH™ RISC engine Family

Section 19 Controller Area Network (RCAN-ET)
(2) Local Acceptance Filter Mask (LAFM)
This area is used as Local Acceptance Filter Mask (LAFM) for receive boxes.
LAFM: When MBC is set to 001, 010, 011 (Bin), this field is used as LAFM Field. It allows a
Mailbox to accept more than one identifier. The LAFM is comprised of two 16-bit read/write
areas as follows.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
H'104 + N*32
IDE_
LAFM
0
0
STDID_LAFM[10:0]
EXTID_
LAFM[17:16]
Word/LW
H'106 + N*32
EXTID_LAFM[15:0]
Word
LAFM Field
Figure 19.4 Acceptance Filter
If a bit is set in the LAFM, then the corresponding bit of a received CAN identifier is ignored
when the RCAN-ET searches a Mailbox with the matching CAN identifier. If the bit is cleared,
then the corresponding bit of a received CAN identifier must match to the STDID/IDE/EXTID set
in the mailbox to be stored. The structure of the LAFM is same as the message control in a
Mailbox. If this function is not required, it must be filled with '0'.
Important: RCAN-ET starts to find a matching identifier from Mailbox-15 down to Mailbox-0.
As soon as RCAN-ET finds one matching, it stops the search. The message will be stored or not
depending on the NMC and RXPR/RFPR flags. This means that, even using LAFM, a received
message can only be stored into 1 Mailbox.
Important: 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 STDID, RTR, IDE and EXTID
may differ to the ones originally set as they are updated with the STDID, RTR, IDE and EXTID of
the received message.
STD_LAFM[10:0] — Filter mask bits for the CAN base identifier [10:0] bits.
STD_LAFM[10:0]
0
1
Description
Corresponding STD_ID bit is cared
Corresponding STD_ID bit is "don't cared"
Rev. 2.00 Sep. 10, 2008 Page 735 of 1130
REJ09B0402-0200