CAN FD v2.0
58
PG223 December 5, 2018
Chapter 2:
Product Specification
Note:
If all UAF bits are set to 0, then the received messages are not stored in any RX FIFO.
IMPORTANT:
Ensure proper programming of the IDE bit for standard and extended frames in the Mask
register and ID register. If you set the IDE bit in the Mask register as 0, it is considered to be a standard
frame ID check only and therefore if Standard ID bits of the incoming message match with the
respective bits of Filter ID (after applying Mask register bits), the message is stored.
AFMR* Register (Address 0x0A00, 0x0A08,…)
The Acceptance Filter Mask registers (AFMR) contain mask bits used for acceptance
filtering. The incoming message identifier portion of a message frame is compared with the
message identifier stored in the acceptance filter ID register. The mask bits define which
identifier bits stored in the Acceptance Filter ID register are compared to the incoming
message identifier for CAN or CAN FD frames.
All bit fields (AMID[28:18], AMSRR, AMIDE, AMID[17:0], and AMRTR) need to be defined for
Extended frames. Only AMID[28:18], AMSRR, and AMIDE need to be defined for Standard
frames. AMID[17:0] and AMRTR should be written as 0 for Standard frames.
X-Ref Target - Figure 2-3
Figure 2-3:
Message Drop (RX FIFO-0 Full
and Match = Yes)
X-Ref Target - Figure 2-4
Figure 2-4:
Message Drop (RX FIFO-1 Full and Match = Yes)
Incoming Message
RX FIFO 1
RX FIFO 0
Match = Yes
Dropped because
RX FIFO 0 is full
FPj = Filter Mask Pair (j = 0,1...31)
Receive Filter Partition (RXFP) = i
FPx
FPi
FP0
FP31
X21311-081618
X21311-081618
X21310-081518
Incoming Message
RX FIFO 0
RX FIFO 1
Match = Yes
Dropped because
RX FIFO 1 is full
FPj = Filter Mask Pair (j = 0,1.31)
Receive Filter Partition (RXFP) = i
FPi
FPx
FP0
FP31
X21310-081618