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Chapter 14 Freescale’s Scalable Controller Area Network (S12MSCANV3)
MC9S12XDP512 Data Sheet, Rev. 2.11
658 Freescale Semiconductor
• Four identifier acceptance filters, each to be applied to
— a) the 14 most significant bits of the extended identifier plus the SRR and IDE bits of CAN 2.0B
messages or
— b) the 11 bits of the standard identifier, the RTR and IDE bits of CAN 2.0A/B messages.
Figure 14-40 shows how the first 32-bit filter bank (CANIDAR0–CANIDA3,
CANIDMR0–3CANIDMR) produces filter 0 and 1 hits. Similarly, the second filter bank
(CANIDAR4–CANIDAR7, CANIDMR4–CANIDMR7) produces filter 2 and 3 hits.
• Eight identifier acceptance filters, each to be applied to the first 8 bits of the identifier. This mode
implements eight independent filters for the first 8 bits of a CAN 2.0A/B compliant standard
identifier or a CAN 2.0B compliant extended identifier. Figure 14-41 shows how the first 32-bit
filter bank (CANIDAR0–CANIDAR3, CANIDMR0–CANIDMR3) produces filter 0 to 3 hits.
Similarly, the second filter bank (CANIDAR4–CANIDAR7, CANIDMR4–CANIDMR7)
produces filter 4 to 7 hits.
• Closed filter. No CAN message is copied into the foreground buffer RxFG, and the RXF flag is
never set.
Figure 14-39. 32-bit Maskable Identifier Acceptance Filter
ID28 ID21IDR0
ID10 ID3IDR0
ID20 ID15IDR1
ID2 IDEIDR1
ID14 ID7IDR2
ID10 ID3IDR2
ID6 RTRIDR3
ID10 ID3IDR3
AC7 AC0CANIDAR0
AM7 AM0CANIDMR0
AC7 AC0CANIDAR1
AM7 AM0CANIDMR1
AC7 AC0CANIDAR2
AM7 AM0CANIDMR2
AC7 AC0CANIDAR3
AM7 AM0CANIDMR3
ID Accepted (Filter 0 Hit)
CAN 2.0B
Extended Identifier
CAN 2.0A/B
Standard Identifier