AT32F425
Series Reference Manual
2022.03.30
Page 325
Ver 2.01
32-bit fliter register CAN_FiFBx includes the SID[10: 0], EID[17: 0], IDT and RTR bits.
CAN_FiFB1[31: 21]
CAN_FiFB1[20: 3]
CAN_FiFB1[2: 0]
CAN_FiFB2[31: 21]
CAN_FiFB2[20: 3]
CAN_FiFB2[2: 0]
SID[10: 0]/EID[28: 18]
EID[17: 0]
IDT
RTR
0
Two 16-bit filter register CAN_FiFBx includes SID[10: 0], IDT, RTR and EID[17: 15] bits
CAN_FiFB1[31: 21]
CAN_FiFB1
[20: 19]
CAN_FiFB1
[18: 16]
CAN_FiFB1[15: 5]
CAN_FiFB1
[4: 3]
CAN_FiFB1
[2: 0]
CAN_FiFB2[31: 21]
CAN_FiFB2
[20: 19]
CAN_FiFB2
[18: 16]
CAN_FiFB2[15: 5]
AN_FiFB2
[4: 3]
CAN_FiFB2
[2: 0]
SID[10: 0]
IDT
RTR
EID[17: 15] SID[10: 0]
IDT
RTR
EID[17: 15]
Filtering mode
The filter can be configured in identifier mask mode or in identifier list mode by setting the FMSELx bit
in the CAN_FMCFG register. The mask mode is used to specify which bits must match the pre-
programmed identifiers, and which bits do not need. In identifier list mode, the identifier must match
the pre-programmed identifier. The two modes can be used in conjunction with filter width to deliver
four filtering modes below:
Figure 19-8
32-bit identifier mask mode
CAN_FiFB1[31:21]
CAN_FiFB1[20:3]
CAN_FiFB2[31:21]
CAN_FiFB2[20:3]
CAN_FiFB1
[2:0]
CAN_FiFB2
[2:0]
SID[10:0]
EID[17:0]
IDT
RTR
0
ID
Mask
Mapping
Figure 19-9
32-bit identifier list mode
CAN_FiFB1[20:3]
CAN_FiFB1
[2:0]
CAN_FiFB2[20:3]
CAN_FiFB2
[2:0]
IDT
RTR
0
CAN_FiFB1[31:21]
CAN_FiFB2[31:21]
SID[10:0]
EID[17:0]
ID
ID
Mapping
Figure 19-10
16-bit identifier mask mode
CAN_FiFB1[15:5]
CAN_FiFB1[4:0]
CAN_FiFB1[31:21]
CAN_FiFB1[20:16]
CAN_FiFB2[15:5]
CAN_FiFB2[4:0]
CAN_FiFB2[31:21]
CAN_FiFB2[20:16]
SID[10:0]
RTR
EID[17:15]
IDT
ID
Mask
ID
Mask
Mapping
Figure 19-11
16-bit identifier list mode
CAN_FiFB1[15:8]
CAN_FiFB1[7:0]
CAN_FiFB1[31:24]
CAN_FiFB1[23:16]
CAN_FiFB2[15:8]
CAN_FiFB2[7:0]
CAN_FiFB2[31:24]
CAN_FiFB2[23:16]
SID[10:0]
RTR
EID[17:15]
IDT
ID
ID
ID
ID
Mapping