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M16C/5L Group, M16C/56 Group
23.1.18 CAN0 Acceptance Filter Support Register (C0AFSR)
CAN0 Acceptance Filter Support Register
b15
Note:
1. Write to the C0AFSR register in CAN operation mode or CAN halt mode.
Figure 23.22 C0AFSR Register
The acceptance filter support unit (ASU) can be used for data table (8 bits × 256) search. In the data
table, all standard IDs created by the user are set to be valid/invalid in bit units. When the C0AFSR
register is written with the 16-bit unit data including the SID bit in the C0MBj register (j = 0 to 31), in
which a received ID is stored, a decoded row (byte offset) position and column (bit) position for data
table search can be read. The ASU can be used for standard (11-bit) IDs only.
The ASU is enabled in the following cases:
• When the ID to receive cannot be masked by the acceptance filter.
Example) IDs to receive: 078h, 087h, 111h
• When there are too many IDs to receive and software filtering time is expected to be shortened.
Figure 23.23 shows the write and read of C0AFSR register.
b15
(1)
When writing
b15
When reading
Column (bit) position in data table
Note:
1. Write the same value as the 16-bit unit data including the SID bit in the C0MBj (j = 0 to 31) register.
Figure 23.23 Write and Read of C0AFSR Register
R01UH0127EJ0110 Rev.1.10
Sep 01, 2011
b0
Symbol
C0AFSR
After the standard ID of a received message is written,
the value converted for data table search can be read
b8
SID10 SID9 SID8 SID7 SID6
3/8 decoder
b8
(1)
Address
D7D7h-D7D6h
Function
b7
SID5 SID4 SID3 SID2 SID1
SID0
b7
SID10 SID9 SID8 SID7 SID6
SID5 SID4 SID3
Row (byte offset) position in data table
23. CAN Module
Reset Value
Undefined
Setting Value
RW
Standard ID/
RW
converted value
Address
CAN0
b0
D7D6h
b0
D7D6h
Page 584 of 803
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