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TCAN1145-Q1: wake up issue

Gary Zeng
Intellectual 1145 points
Part Number: TCAN1145-Q1

Tool/software:

Hi TI experts,

My customer uses TCAN1145 in PDU products and met below three questions:

Q1: When TCAN1145 go into sleep mode and it will be waked up due to the accumulated number of error frames.

       How can they avoid it. All they need are WUF(special ID) wake up？Is it useful to set FRAME_OVF_ENABLE to 0? Customer tried it before going into sleep mode. But it doesn't work 

Q2: Register 56h can not be setted up when TCAN1145 is in normal working mode.

       Customer tried to set 56h to from default 0xff to 0x40 in 10ms. But it will be 0x40 after the customer's operation but soon will automatically be setted to 0xff during 10ms period. Customer need to set it again but it will aslo back to 0xff again. 

Q3: Customer uses CAN fault generator to artificially make CAN frame fault. But when customer reads the register of 45h(FRAME_CNTx), it will not add 1 after they make one time CAN frame fault. Why?

  • 0
    TI__Guru 53555 points

    Hi Gary,

    1. There is no way to disable the wake via frame overflow. This is a safety mechanism to ensure that the local node is able to wake up in the case that the transceiver has a problem decoding the information on the CAN bus or if the CAN bus is no longer able to properly transmit data. To reduce the occurrence of wake via CAN overflow, the SW_CONFIG_1.SW_FD_PASSIVE bit can be set to ignore CAN FD frames, and the SW_CONFIG_3.FRAME_CNT_THRESHOLD can be set to max value (255) to increase the number of error frames needed in order to wake the device. 
    The FRAME_OVF_ENABLE bit only controls if the FRAME_OVF flag is indicated on the nINT pin. This field does not impact device behavior otherwise. 

    2. This register should only reset its value due to a reset condition (POR, SF_RST, HD_RST). Otherwise the value written to this register should be maintained. Can you confirm that none of these reset conditions take place? Is the written value verified immediately after the initial write takes place?

    3. The Bus Fault Detection circuitry is a bit particular. In short it may take multiple CAN frames before the transceiver is able to detect the bus fault. The detection circuit also works better at lower data rates (does not work above 1Mbps) and is more reliable when the fault is strong (i.e. hard short to GND rather than 100-ohms to ground). 
    I recommend repeating this test with multiple CAN frames at a nominal data rate (non-FD frames) and ensuring the fault is strong.
    Do you know if the customer intends to use this feature in the end equipment? 

    Regards,
    Eric Schott

  • 0 in reply to Eric Schott1
    TI__Intellectual 1145 points

    Hi Eric,

    Thanks for your help.

    Customer follows your two suggestions about Q1. It will not be waked up anymore when it is in sleep mode unless there is a WUF. Is it meanning that wake-up event is casued by CAN-FD frame.Customer said CAN format they uses should be standard CAN rather than CAN-FD. data bit is 8.

    Could you please help review the software codes. document 1 is about POR Initialize and document 2 is for going into sleep mode.

    TCAN1145 POR initialize.docx

    TCAN1145 go into sleep mode.docx

    For Q2, they can successfully change the registers now.

  • 0 in reply to Gary Zeng
    TI__Intellectual 1145 points

    Problems encountered at present
    • Errors in error frames will not make the error accumulation register +1, at 500kbps, regardless of whether CAN-FD is shielded

    • Not sure whether the frame currently sent is standard CAN or CAN-FD


    • After using the CAN-FD shielding function
    ○ Non-ID specific frames at a communication rate of 500kbps will not wake up the sleep state
    ○ 500kbps ID specific frames will wake up the sleep state
    ○ 250kbps specific frame ID will not wake up the sleep state
    ○ But non-specific frames at 250k will wake up the sleep state. Could it be that this 250k is a standard CAN frame, and the CAD-FD shield cannot shield it

  • 0 in reply to Gary Zeng
    TI__Guru 51106 points

    Hi Gary,

    Today is a holiday. Please give some time until Monday for feedback, thanks.

    Best Regards,

    Michael.