SPRACU9 October   2021 TMS320F2800152-Q1 , TMS320F2800153-Q1 , TMS320F2800154-Q1 , TMS320F2800155 , TMS320F2800155-Q1 , TMS320F2800156-Q1 , TMS320F2800157 , TMS320F2800157-Q1 , TMS320F280033 , TMS320F280034 , TMS320F280034-Q1 , TMS320F280036-Q1 , TMS320F280036C-Q1 , TMS320F280037 , TMS320F280037-Q1 , TMS320F280037C , TMS320F280037C-Q1 , TMS320F280038-Q1 , TMS320F280038C-Q1 , TMS320F280039 , TMS320F280039-Q1 , TMS320F280039C , TMS320F280039C-Q1 , TMS320F28384D , TMS320F28384D-Q1 , TMS320F28384S , TMS320F28384S-Q1 , TMS320F28386D , TMS320F28386D-Q1 , TMS320F28386S , TMS320F28386S-Q1 , TMS320F28388D , TMS320F28388S , TMS320F28P550SJ , TMS320F28P559SJ-Q1 , TMS320F28P650DH , TMS320F28P650DK , TMS320F28P650SH , TMS320F28P650SK , TMS320F28P659DK-Q1

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 MCAN Features
  3. 2Useful tips to run the C2000ware examples
  4. 3Program Descriptions
  5. 4Debug and Design Tips to Resolve/Avoid CAN Communication Issues
    1. 4.1 Minimum Number of Nodes Required
    2. 4.2 Why a Transceiver is Needed
    3. 4.3 Debug Checklist
      1. 4.3.1 Programming Issues
      2. 4.3.2 Physical Layer Issues
      3. 4.3.3 Hardware Debug Tips
  6. 5How to Duplicate (clone) an Existing Project
  7. 6How to Get Visibility Into Driverlib Files
  8. 7References

4.2 Why a Transceiver is Needed

One cannot directly connect MCANTX of node-A to MCANRX of node-B and vice versa and expect successful CAN communication. In this case, CAN is unlike other serial interfaces like SCI or SPI. For example, SCI can be made to work with a RS232 transceiver or through a direct connection (SCITX of one node to SCIRX of another node and vice versa). However, CAN bus needs a CAN transceiver for the following reason: In addition to converting the single-ended CAN signal for differential transmission, the transceiver also loops back the CANTX pin to the CANRX pin of a node. This is because a CAN node needs to be able to monitor its own transmission. Why?

  • This has to do with the ACK requirement mandated by the CAN protocol. When a node transmits a frame on the CAN bus, it expects an ACK from at least one other node on the network. For the ACK phase, the transmitter puts out a 1 and expects to read back a 0.
  • During arbitration, a node with a higher-priority MSGID needs to be able to override a 1 with a 0. Here again, the transmitter needs to be able to read back the transmitted data. When a node puts out a 1 and reads back a 0 during the arbitration phase, it loses arbitration.