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TCAN1145-Q1: Wake up by fault frame

Scarlett Cao
Expert 4410 points

Part Number: TCAN1145-Q1

Hi team,

My customer has several questions on TCAN1145-Q1 related to waking up by fault frame.

1. In INT_ENABLE_1 register field, customer has only configured CANINT_ENABLE and LWU_ENABLE. The other bits like frame overflow counter is not enabled.  But the system can still be wake up by fault frame. Could you explain what might be the possible reasons?

2. Customer also tried disable CANINT_ENABLE, still cannot disable wake up by CAN frame.

3. When wake up by fault frame, customer reads INT_ENABLE_1 register, they found CANINT, FRAME_OVF are 1. Also they found only one fault frame can wake up TCAN1145, different from 32 as described in datasheet. FRAME_CNT_THRESHOLD register is same as default 31. Why?

4.May I know after wake up by fault frame, which bits in INT_ENABLE_1 register will turn 1? Customer observes both CANINT and FRMAE_OVF are turned 1. At their customer side, it also occurs that occasionally FRAME_OVF and LWU bit turn 1.

Thanks and looking forward to your feedback.

Scarlett

  • 0
    TI__Expert 4410 points

    src_CanTrcv registor dump.zip

    please check customer register setting in attachment

  • 0 in reply to Scarlett Cao
    TI__Guru 74302 points

    Scarlett,

    Disabling these interrupts in the registers only disables the indication by the nINT pin. The interrupt still occurs internally, it is not possible to disable wake by CAN frame on the TCAN1145-Q1 device.

    For the FRAME_CNT_THRESHOLD being surpassed, can the customer also read register 0x45? This will show the actual count the device is seeing.

    Regards,

    Eric Hackett

  • 0 in reply to Eric Hackett
    TI__Expert 4410 points

    Hi Eric, 

    Thanks for your reply :) 

    Customer did not read the number of error frames, but through the bus message. They only found one error frame was recorded on the bus. The triggering method of the error frame is to connect the 250K bus on the 500K bus.

    Customer would like to confirm for below question:

    May I know after wake up by fault frame, which bits in INT_ENABLE_1 register will turn 1? My customer observes both CANINT and FRMAE_OVF are turned 1. At their customer Car OEM side, it also occurs that occasionally FRAME_OVF and LWU bit turn 1. Is that normal?

    Thanks

    Scarlett

  • 0 in reply to Scarlett Cao
    TI__Guru 74302 points

    Scarlett,

    So the customer is setting the TCAN1145-Q1 to read 500kbps and then transmitting 250kbps to force the error?

    I've reached out to our design team to verify the customer's question. I don't think the LWU bit is supposed to assert, but I want to verify that.

    Regards,

    Eric Hackett

  • 0 in reply to Eric Hackett
    TI__Guru 74302 points

    Scarlett,

    I got information back from the design team and I was right, they shouldn't be seeing the LWU flag asserted. How this function works is that FRAME_OVF flag will be asserted once the device wakes from a frame overflow, and then CANINT will be asserted because the device will see another WUP while in Standby mode from a CAN frame. LWU should only be asserted if the WAKE pin is used to wake the device. The fact that there are instances where FRAME_OVF is asserted but not CANINT is also not expected.

    Can you give specific details of their test procedure? Are they sending a specific amount of CAN frames every time, or are they just sending frames until the device wakes from FRAME_OVF?

    Regards,

    Eric Hackett