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TCAN1146-Q1: TCAN1146-Q1 Sleep and wakeup not working

AKHIL GUPTA
Prodigy 190 points
Part Number: TCAN1146-Q1

Hi,

Currently I am testing sleep and wakeup feature for TCAN1146 -Q1,Hence i am facing with generation of wakeup pattern(WUP)

According to datasheet CAN bus wake-up must occur, and then the correct wake-up frame must be transmitted.
So we are sending WUP (ISO11898-2:2016 )on CAN Bus as follows:
Wake up Pattern generation at 500 kBit/s:
 
With one CAN frame that provides two dominant phases with at least 3 bits length separated by a recessive phase of 3 bits(000111000)
WUP CAN Frame configured on CANOE @ 10 ms periodicity:
Baud Rate : 500 kBit/s
CAN ID: 0x238
CAN DATA:  0x38e38e38
 
Observing CAN Tx Err on CANOE(Not Acknowledged  Error, dominant error flag)
Tried with WUP(010) 1 bits length separated by a recessive phase of 1 bits(010)
So just want to check whether this is a correct WUP or not .
Configuration for Selective wakeup register for wakeup frame(WUF) in cantransceiver code:
Extended CAN ID:0x14003807x
CAN DATA :0x74000080
DLC :8 Byte
DATA MASK Enabled.
CAN Data baud rate:500kbps

Register

Value

SW_ID_1

0x0E

SW_ID_2

0x01

SW_ID_3

0xf4

SW_ID_4

0x00

SW_ID_MASK_1

0x00

SW_ID_MASK_2

0x00

SW_ID_MASK_3

0xFF

SW_ID_MASK_4

0x00

SW_ID_MASK_DLC

0x11

DATA_0

0x7

DATA_1

0x4

DATA_2

0x00

DATA_3

0x00

DATA_4

0x00

DATA_5

0x00

DATA_6

0x80

DATA_7

0x00

SW_CONFIG_1

0x50

SW_CONFIG_2

0x00

SW_CONFIG_3

0x1F

SW_CONFIG_4

0x00

CANOE Configuration for NM Frame @ Periodicity 500ms

Extended CAN ID:0x14003807x
CAN DATA :0x74000080.
Can anyone please provide their input to solve the problem
Regards
Akhil
  • 0
    TI__Guru 60262 points

    Akhil,

    Thanks for bringing this to E2E, I know we're working with this through email, but just to address some of your questions here.

    Since the WUP on the TCAN114x-Q1 transceiver requires a dominant-recessive-dominant pattern on the CAN bus, with each state needing to last at the longest 1.8us, virtually any CAN frame at 500kbps will work as a WUP. When selective wake is enabled, the device is in sleep mode, and the WUP is correctly received, the CAN bus will then be biased to 2.5V. Once this occurs, "training" frames will need to be sent so that the WUF receiver can measure the time between edges and lock in to the bus data rate so that it can correctly receive the wake-up frame. 

    The not acknowledged error makes sense since you are sending a CAN frame to a node where the transceiver is asleep. This means that the controller cannot receive the CAN message to acknowledge it, thus the transmitting controller sees this as the message was not correctly received by the bus and throws an error. The dominant error is strange, because this occurs when the transceiver transmitted a dominant bit but the RXD pin returns a recessive. Is this error happening every time the CAN frame is transmitted, or just initially when the CAN bus first responds to the WUP?

    Regards,

  • 0 in reply to Eric Hackett
    Prodigy 190 points

    Hi Eric,

    Thanks for your timely reply.

    As per your Query: "Is this error happening every time the CAN frame is transmitted, or just initially when the CAN bus first responds to the WUP?" 

    Ans :This  happens when the CAN bus first responds to the WUP

    There are few query based on your inputs, Those are:

    1) How are  these "training frames"  are transmitted and who is sending it?

    2)Will below configuration work as a valid WUP

    Baud Rate : 500 kBit/s
    CAN ID: 0x238
    CAN DATA:  0x38e38e38
    it is making a structure of dominant -recessive-dominant.
    3)Can you please recommend to do some checkpoint to figure out dominant error flag bit?
    Regards
    Akhil

  • 0 in reply to AKHIL GUPTA
    TI__Guru 60262 points

    Akhil,

    The dominant error is most likely being thrown because the CAN bus is biasing from 0V to 2.5V after the WUP is received and thus the transceiver may miss a dominant bit because CANH and CANL aren't meeting the differential threshold for a dominant bit. 

    1) The training frames are merely CAN frames at 500kbps or 1Mbps sent by the same node that is sending the WUP and the WUF. The intention is so the WUF receiver can properly lock-in to the CAN bus data rate prior to sampling the WUF.

    2) Yes, that should work just fine. The dominant and recessive filter time for the WUP on this device is typically greater than 1.8us, so at 500kbps, each bit is 2us and will be interpreted as a WUP by the low-power receiver.

    3) Since it is happening at the initial wake, it may be best just to ignore it in these cases. Is that possible in your system?

    Regards,