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TMS320F28377D: About acceptance filtering in the CAN module

lei li
Intellectual 375 points

Part Number: TMS320F28377D

Hi, according to the TMS320F2837xD TRM, there were some register bits about acceptance filtering, such as "UMask、MXtd、MDir、Msk".

1、If I want to filter the Received Frame with MXtd/MDir/Msk.Should I set the UMask bit FIRST? Or in other words, the UMask bit is a TOP Enable switch for acceptance filtering?

2、Was it only filter Xtd/Dir/ID in the CAN module?

3、According to “Then the arbitration and mask bits (including MsgVal, UMask, NewDat, and EoB) of Message Object 1 are loaded into the Acceptance Filtering unit and are compared with the arbitration bits from the shift register.” from “22.11.6 Acceptance Filtering of Received Messages”.  Why the bit(MsgVal、NewDat, and EoB) will be filter in the Acceptance Filtering unit?

      Thanks!

  • 0
    TI__Guru* 95315 points

    Please take a look at the filtering example in http://www.ti.com/lit/sprace5 and let me know if you still have questions

  • 0
    TI__Guru* 95315 points
    lei li said:
    1、If I want to filter the Received Frame with MXtd/MDir/Msk.Should I set the UMask bit FIRST? Or in other words, the UMask bit is a TOP Enable switch for acceptance filtering?

    The CAN_setupMessageObject() function is used to configure the mailbox. It writes to all the configurations bits of the mailbox in one go. The UMask bit must be active for filtering.

    lei li said:
    2、Was it only filter Xtd/Dir/ID in the CAN module?

    I don't understand the question. Filtering is done based on the Arbitration (MSGID) field.

    lei li said:
      Why the bit(MsgVal、NewDat, and EoB) will be filter in the Acceptance Filtering unit?

    MsgVal is used to signal that it is a valid Message Object. NewDat bit may be used to determine if the previous message has been read. EoB is used to determine if the Message object is part of a FIFO. In any case, these are design details that are not critical to the understanding of the filtering function. What is important is to be aware that the Arbitration field and the mask are used for filtering.