SLLA521B January   2022  – June 2022 TCAN1145-Q1 , TCAN1146-Q1

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction – Partial Networking
  4. 2Partial Networking Application
    1. 2.1 Modes of Operation and Partial Networking
    2. 2.2 Sleep Mode and Partial Networking
    3. 2.3 Wake-Up Frame
    4. 2.4 Classical High-speed CAN, CAN FD, and PN
    5. 2.5 Mixed Network Information
  5. 3CAN Frames and Wake-up Frames
    1. 3.1 CAN Frame Structure
    2. 3.2 Wake-up Frames
      1. 3.2.1 ID Field Match
      2. 3.2.2 Data Length Code (DLC) Match
      3. 3.2.3 Data Match
      4. 3.2.4 CRC Match
      5. 3.2.5 Acknowledge Match
    3. 3.3 Error Counter
    4. 3.4 Selective Wake FD Passive
  6. 4Selective Wake Registers
  7. 5Configuring Partial Networking
    1. 5.1 Valid CAN Message ID Example
    2. 5.2 Valid Data Example
  8. 6Summary
  9. 7References
  10. 8Revision History

3.2.1 ID Field Match

The first criteria for a WUF is that the ID Field must match. This can be either an 11-bit Base ID for CBFF, or the 29-bit Extended ID for CEFF. A configuration register (IDE) will define which one to use (0=Base ID, 1=Extended ID). A matching ID does not have to match every bit of the programmed ID field. Some bits may be masked, so that either a 0 or a 1 in that bit position is considered a match. For instance, the following 11-bit Base ID, the ID Mask field, and the received Base ID. In the ID Mask field a 0 means the value must match and a 1 means the value is disregarded.

Figure 3-2 ID Field

In this example, the configured IDE bit would be 0 (11-bit ID field), the Configured ID is set by the register ID[10:0], and the Mask Register would be set by register ID_MASK[10:0]. In the ID_MASK field, a 1 is a mask, or disregard, and a 0 is a care. So, for the 11-bits, all care bits must match the programmed ID[n] bit, while all disregard care bits are accepted as a match. If all bits in the ID field are matching, then the ID filed is accepted as a WUF ID match.

If the configuration register DATA_MASK_EN=0, then only the ID field has to match. The rest of the CAN frame must still be decoded and have a correct CRC field, followed by a recessive bit (the CRC delimiter) to be considered a valid WUF.