SLAAET4 April   2025 MSPM0G3506 , MSPM0G3507 , MSPM0G3518 , MSPM0G3519

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 MCAN Features
  5. 2Sysconfig Configuration for MCAN Module
    1. 2.1 MCAN Clock Frequency
    2. 2.2 MCAN Basic Configuration
      1. 2.2.1 Transmitter Delay Compensation (TDC)
      2. 2.2.2 Bit Timing Parameters
      3. 2.2.3 Message RAM Configuration
        1. 2.2.3.1 Standard and Extended ID Filter Configuration
          1. 2.2.3.1.1 How to Add More Filters
        2. 2.2.3.2 TX MSG RAM
        3. 2.2.3.3 RX MSG RAM
    3. 2.3 Advanced Configuration
    4. 2.4 Retention Configuration
    5. 2.5 Interrupts
    6. 2.6 Pin Configuration and PinMux
  6. 3Demo Project Descriptions
    1. 3.1 TX Buffer Mode
    2. 3.2 TX FIFO Mode
    3. 3.3 RX Buffer Mode
    4. 3.4 RX FIFO Mode
  7. 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 Bus Off Status
    4. 4.4 Using MCAN in Low Power Mode
    5. 4.5 Debug Checklist
      1. 4.5.1 Programming Issues
      2. 4.5.2 Physical Layer Issues
      3. 4.5.3 Hardware Debug Tips
  8. 5Summary
  9. 6References

4.1 Minimum Number of Nodes Required

Unless working in self-test mode, a minimum of two nodes are needed on the CAN bus for the following reason. When a node transmits a frame on the CAN bus, the node expects an acknowledgment (ACK) from at least one other node on the network. Anytime a CAN node successfully receives a message, the node automatically transmits an ACK, unless that feature has been turned off (silent mode. Silent node is where a node receives the frame, but does not provide an ACK; the bus monitoring mode in MCAN). The node that provides the ACK does not need to be the intended recipient of the frame, although this can happen. (All active nodes on the bus provide an ACK, regardless of whether the nodes are the intended recipients of that frame).

When the transmitting node does not receive an ACK, this results in an ACK error and the transmitting node keeps retransmitting the frame forever. The Transmit Error Counter (TEC) increments to 128 and stops there. REC stays at 0. The node does not go bus-off. No interrupts are generated either. If another node is brought into the network, then TEC starts decrementing (all the way to 0) with every successful transmit.