DocID018909 Rev 11 1081/1731
RM0090 Controller area network (bxCAN)
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Figure 343. Example of filter numbering
Filter priority rules
Depending on the filter combination it may occur that an identifier passes successfully
through several filters. In this case the filter match value stored in the receive mailbox is
chosen according to the following priority rules:
• A 32-bit filter takes priority over a 16-bit filter.
• For filters of equal scale, priority is given to the
Identifier List mode over the Identifier
Mask mode
• For filters of equal scale and mode, priority is given by the filter number (the lower the
number, the higher the priority).
9
8
ID List (32-bit)
ID Mask (32-bit)
ID List (16-bit)
ID List (32-bit)
Deactivated
ID Mask (16-bit)
ID List (32-bit)
Filter
0
1
3
5
6
9
ID Mask (32-bit)
13
FIFO0
Filter
0
1
2
3
4
5
6
7
10
11
12
13
ID Mask (16-bit)
ID List (32-bit)
ID Mask (16-bit)
ID List (16-bit)
Deactivated
ID Mask (16-bit)
ID List (32-bit)
Filter
2
4
7
8
10
11
ID Mask (32-bit)
12
FIFO1
Filter
0
1
2
4
5
6
7
8
11
12
13
14
3
Deactivated
9
10
Num. Num.BankBank
ID=Identifier