34.9.5 Standard Message ID Filter Element

Up to 128 filter elements can be configured for 11-bit standard IDs. When accessing a Standard Message ID Filter element, its address is the Filter List Standard Start Address SIDFC.FLSSA plus the index of the filter element (0 ... 127).

Table 34-12. Standard Message ID Filter Element
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
S0 SFT

[1:0]

 SFEC

[2:0]

 SFID1[10:0] SFID2[10:0]

  • Bits 31:30 - SFT[1:0]: Standard Filter Type

    This field defines the standard filter type.

    Table 34-13. Standard Filter Type
    Value Name Description
    0x0 RANGE Range filter from SFID1 to SFID2 (SFID2 >= SFID1)
    0x1 DUAL Dual ID filter for SFID1 or SFID2
    0x2 CLASSIC Classic filter: SFID1 = filter, SFID2 = mask
    0x3 RES Reserved

  • Bits 29:27 - SFEC[2:0]: Standard Filter Element Configuration

    All enabled filter elements are used for acceptance filtering of standard frames. Acceptance filtering stops at the first matching enabled filter element or when the end of the filter list is reached. If SFEC = “100”, “101”, or “110” a match sets interrupt flag IR.HPM and, if enabled, an interrupt is generated. In this case register HPMS is updated with the status of the priority match.

    Table 34-14. Standard Filter Element Configuration
    Value Name Description
    0x0 DISABLE Disable filter element
    0x1 STF0M Store in Rx FIFO 0 if filter matches
    0x2 STF1M Store in Rx FIFO 1 if filter matches
    0x3 REJECT Reject ID if filter matches
    0x4 PRIORITY Set priority if filter matches.
    0x5 PRIF0M Set priority and store in FIFO 0 if filter matches.
    0x6 PRIF1M Set priority and store in FIFO 1 if filter matches.
    0x7 STRXBUF Store into Rx Buffer or as debug message, configuration of SFT[1:0] ignored.

  • Bits 26:16 - SFID1[10:0]: Standard Filter ID 1

    First ID of standard ID filter element.

    When filtering for Rx Buffers or for debug messages this field defines the ID of a standard mesage to be stored. The received identifiers must match exactly, no masking mechanism is used.

  • Bits 15:11 - Reserved

  • Bits 10:0 - SFID2[10:0]: Standard Filter ID 2

    This bit field has a different meaning depending on the configuration of SFEC.


    1. SFEC = “001” ... “110”: Second ID of standard ID filter element.

    2. SFEC = “111”: Filter for Rx Buffers or for debug messages.

    SFID2[10:9] decides whether the received message is stored into an Rx Buffer or treated as message A, B, or C of the debug message sequence.
 00 = Store message into an Rx Buffer
 01 = Debug Message A
 10 = Debug Message B
 11 = Debug Message C

    SFID2[8:6] is used to control the filter event pins at the Extension Interface. A ‘1’ at the respective bit position enables generation of a pulse at the related filter event pin with the duration of one CLK_CAN_AHB period in case the filter matches.

    SFID2[5:0] defines the offset to the Rx Buffer Start Address RXBC.RBSA for storage of a matching message.