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Original question:

TCAN1145-Q1: CANINT behavior

TCAN1145-Q1: Unexpected CANINT Bit Set on TCAN1145

Wonder Fang
Prodigy 465 points

Part Number: TCAN1145-Q1

Hi Team,

One of my customers found that the CANINT bit in the INT_1 (0x51) register is being set unexpectedly after only WAKE pin was used for wake-up. There do have non-related messages on CAN but confirmed no intended WUF on the CAN bus. As a consequence, they could no tell whether the wake source is from WUF or LWU. 

Issue Description:

  • Scenario: Device is in Sleep mode; CAN bus contains unrelated (non-network management) frames; device is woken up via the WAKE pin.
  • Observation: After wake-up, both the LWU and CANINT bits in INT_1 are set, whereas only LWU is expected according to the datasheet. 

Debug already done:

  • Sending only network management frames will not wake up the controller (no change in current consumption).
  • Disconnecting the CAN bus and waking up via the WAKE pin will not set the CANINT bit.

Quetsions:

  • If the CANINT should only be set if a valid CAN bus wake-up event (WUP or WUF) is detected? 
  • Any suggest further diagnostic steps? 

 

Regards,

Wonder Fang

  • 0
    TI__Mastermind 29862 points

    Hi Wonder,

    CANINT is raised from either a WUP (any CAN frame) or WUF (specific CAN frame with matching ID). Please double check how/when Selective Wake is enabled. 

    In Standby mode, the low power receiver that detects WUP is active. So it is possible that when the Wake pin wakes the device into Sleep mode, TCAN1145 raises the CANINT flag since the network management frame is a valid WUP. 

    Overall, TCAN1145 seems to be working properly. Just have your customer clear all INT_x flags before proceeding into Normal mode. This is what we recommend as the normal procedure anyway.

    Best,

    Ethan

  • 0 in reply to Ethan Sempsrott
    TI__Expert 4039 points

    Hi Ethan,

    I'm wondering if selective wake up is selected, then CANINT should be triggered by WUF rather than WUP right? If so, this should be an unexpected behavior as Wonder described. 

    Best.

    Josh

  • 0 in reply to Josh Wei
    TI__Mastermind 29862 points

    Hi Josh,

    Yes, if Selective Wake is enabled, then CANINT means that a valid WUF was detected. If Selective Wake is disabled, then any CAN frame will raise the CANINT flag. 

    Best,

    Ethan