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INT-What cause F28335 stuff bit error frequently occur?

Yanming Luo
Guru** 117160 points

Champs,

A customer used F28334 eCAN module to communicate with SJ1000 control board, and met F28335 eCAN frequently stuff bit error (SE) ocurred, so the actual CAN commincation speed is very slow. What state or condition will cause eCAN of F28335 to occur SE? How to avoid or reduce SE? Thanks!

Best Regards,

Yanming

  • 0
    Mastermind 7585 points

    The CAN stuff bit rule check is implemented in hardware. According to the CAN standard a transmitter will interleave a single stuff-bit after 5 consequtive bits of identical level, e.g. 00000000 is actually transmitted as 000001000. All CAN receivers will remove the stuff bit automatically. However, if a receiver still gets 6 consequitve bits of the same level, it will raise an "Stuff-bit Error".

    In most cases a shift in the data rates of the nodes is the cause of these errors. If you cannot spot any mismatches in the intialization code for the 28334 and the SJA1000, I'd recommend to measure the bit timing of messages from (a) the F28334 and (b) from the SJA1000.

    Another cause could be any physical signal abnormalities, such as disturbances, slope times,etc.  all depending on the physical setup of your customer CAN.

    Regards

     

     

  • 0 in reply to Frank Bormann
    Prodigy 250 points

    I'm sorry.

    How can I reset SE (stuff error) bit in CANES register without reconfigurating eCAN module in TMS320F2833x?

  • 0 in reply to Alex Berg
    Mastermind 7585 points

    Alex,

    page 42 of sprueu1.pdf  describes the CAN-ES register. It says to acknowledge and clear an error bit, you have to write a 1 to the corresponding bit position. No need to re-initialize the module.