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TMS470MF06607: DCAN transceiver change

arun kumar93
Expert 1060 points
Part Number: TMS470MF06607

hi ,

i am using TMS470MF06607 microcontroller. (TMS470M HDK  development kit).

in this launchpad the transceiver is build on the board. 

i tried to connect this CAN module to the external transceiver. i take the CAN TX & RX pin from the launchpad.

if i connect the normal CAN high speed transceiver means its working properly.

but , here i tried to connect the FTCAN transceiver(Fault tolerent ).

now the data is not transmited to the another CAN module(SAINT TOOL).

i dont know the reason . its any software issue, or an hardware issue. 

regards

Arun kumar.N

  • 0
    TI__Guru 59540 points

    Hello Arun,

    I am not very familiar with the FTCAN so perhaps if you could provide a specific part number and supplier I could review to see if there might be a compatibility issue. However, the first thing you should check is if the interface pins on the FTCAN device are 3V tolerant. The CANTX and RX pins on the MCU are 3V signals which should be considered when selecting a transceiver. 

  • 0
    TI__Guru 59540 points
    Hello Arun,

    I 've done some additional investigation considering the device TJA1055 from another supplier other than TI and for this specific device the voltage levels should be OK but you should verify with an oscilloscope to insure the voltage levels match the datasheet for the device you are using. Also, in reviewing the datasheet for this other part, I see that it is only valid up to 125kbps which is very slow for CAN so this is another area that you should check to make sure you haven't exceeded the capability of the transceiver you are using. The max CAN baud rate for the TMS470MF06607 is 1Mbps as per the CAN 2.0 standard.
  • 0 in reply to Chuck Davenport
    Expert 1060 points
    hi ,

    i am also used the TJA1055T/3 transceiver. i am applied the the voltages like
    14 pin - 12v (VBAT)
    10 PIN - 5v (vcc)
    3 & 4 pin - 3.3v (i supplied this voltage through the 3.3k resistance).

    but i did not get any data transmission to the saint tool.
    if u want i can send my schematic diagram to you. can you please tell me the what i want to done further in my side.
    sir, is it not any software issue right ????

    thanks
    Arun Kumar.N
  • 0 in reply to arun kumar93
    Expert 1060 points
    hi sir,

    in that TJA1055T/3 , I dont know about some connections.
    pin no : 4 (TJA1055T/3) is connected to my controller(TMS470MF06607) HET2 pin (from transceiver output is goto the controller).
    pin no : 5 (TJA1055T/3) is connected to my controller HET1 pin. (from controller output is goto the transceiver).
    pin no : 6 (TJA1055T/3) is connected to my controller HET0 pin.(from controller output is goto the transceiver).

    in my software side i did not make anything for those pin. i dont know what i want to for those pins. because that HET pins we can make it as a GPIO/PWM .

    can you please tell me , what functionality i want to make those pins.


    regards
    Arun kumar.N
  • 0 in reply to arun kumar93
    TI__Guru 59540 points
    Hello Arun,

    The TJA1055T/3 device is not a TI device so I cannot offer any guidance on it. I would strongly suggest that you discuss with the supplier of the device (I believe it is NXP) since they are experts on it and you have already mentioned that the DCAN module was working fine with the provided transceiver on the HDK indicating there isn't an issue with the SW or the TMS470M device/HDK.
  • 0 in reply to arun kumar93
    TI__Guru 59540 points
    I would make one quick observation on your last post. Why are you connecting HET pins and PWMs to the CAN transceiver? The CANTX and RX pins from the MCU should be connected to it. Power for the device should come from your power supply and outputs to the CAN bus with proper termination resistances in place.
  • 0 in reply to Chuck Davenport
    TI__Guru 72500 points
    How did you connect the TJA1055T pins 2 and 3 to the TMS470M HDK? You cannot just connect to the expansion pins on J11 because the TI CAN drivers (U2 and U3) are already driving the CAN1SRX and CAN2SRX pins. You cannot have two transceivers trying to drive the same CANnSRX pin on the TMS470 device.
  • 0 in reply to Bob Crosby
    Expert 1060 points
    hi ,

    from my TMS470M HDK , i can take that CANTX and CANRX pins from the back side of that board. so i take that CANTX and CANRX pins and connect a external transceiver means it will work .
    i checked with that external transceiver for normal CAN . its working properly.
    so, thats why i connect with that FTCAN transceiver.

    thanks
    Arunv Kumar.N
  • 0 in reply to arun kumar93
    TI__Guru 72500 points
    What you have done is not correct. The CANRX pin from the transceiver is a push-pull output. You cannot connect two push-pull outputs together. When you do, it may or may not work depending on the relative strength of the output driver, but in the end one of the chips will fail. If you want to use an "off-board" can transceiver you must remove the on-board can transceiver. (Doing so will of course void your warranty.) For DCAN1 the on-board transceiver is U2. For DCAN2 it is U3.
  • 0 in reply to Bob Crosby
    Expert 1060 points
    hi sir,
    sorry for the delayed response sir. thank you for your suggestions.

    regards
    Arun Kumar.N