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

4.5.2 Physical Layer Issues

  • Has the bus been terminated correctly (with 120Ω) at either ends only? The bus must be terminated only at either ends and with a 120Ω resistor. No more than two terminator resistors can be present on the bus, unless split termination is followed, in which there are two resistors on either ends. While designing a CAN bus system, the termination resistors can be enabled or disabled from outside the system enclosure. This scheme is easy for when nodes have to be added or removed to and from the network.
  • Are all CAN nodes configured for the same bit-rate? Mismatched node bit rates repeatedly introduce error frames on the bus. Capture the output of the CAN_TX pin on the oscilloscope to physically verify the bit-time.
  • Have users tried a lower bit-rate? For example, 50kbps. Timing issues concerning propagation delays can be caught trying a lower bit-rate. Make sure that the bit timing parameters are configured correctly in Sysconfig.
  • Have users tried to reduce the bus length and number of nodes?
  • Before the error condition occurs, were any error-frames seen on the bus? This can be timing violations or noise issues.
  • How many nodes are there in the bus? (In non-self-test mode, there must be at least two nodes on the network, due to the acknowledge (ACK) requirement mandated by the CAN protocol).