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Thread: Teensy 3.6 CAN LIN Board

  1. #1
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    Teensy 3.6 CAN LIN Board

    I want to create my own CAN/LIN board for the Teensy3.6. (Using MCP2004 and MCP2551, because I have access to these transceivers)
    I am trying to make the board with 2 CAN channels and 2 LIN channels (and I want to have access to all the other Teensy pins as well).

    This is the complete schematics:
    Click image for larger version. 

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    I have a couple of questions here that I hope you guys can help me with:
    (also please know that I am not a hardware designer so the questions might be stupid)
    • Should I be connecting the transceivers VCC-pin to the Teensy VIN (3.6-6 Volt) or to the Teensy 3.3 Volt? (I think I should be using the 3.3Volt but can it support enough current for all the 4 transceivers)?
    • for the CAN transivers, should I connect RXD to Teensy CANxRX (and TXD to Teensy CANxTX) or is it the other way around? Aka TX to RX and RX to TD? I seem to always get this wrong?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by alborz; 01-29-2017 at 11:30 AM.

  2. #2
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    In the new schematics, Teensy VIN is connected to 3.3V.

    Quote Originally Posted by alborz View Post
    • Should I be connecting the transceivers VCC-pin to the Teensy VIN (3.6-6 Volt) or to the Teensy 3.3 Volt? (I think I should be using the 3.3Volt but can it support enough current for all the 4 transceivers)?
    LIN transceiver min. VBB is 6V (max 27V). It won't work with 3.3V.
    CAN transceiver min. VCC is 4.5V (max 5.5V). It won't work with 3.3V.

    Connect LIN transceiver RX pull up resistor to 3.3V and not 5V. Teensy 3.6 is not 5V tolerant, applying >3.6V to any pin (except VIN) can destroy your Teensy.

    Quote Originally Posted by alborz View Post
    • for the CAN transivers, should I connect RXD to Teensy CANxRX (and TXD to Teensy CANxTX) or is it the other way around? Aka TX to RX and RX to TD? I seem to always get this wrong?
    TXD to Teensy CANxTX
    RXD to Teensy CANxRX
    Last edited by HWGuy; 01-29-2017 at 12:17 PM.

  3. #3
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    Quote Originally Posted by HWGuy View Post
    In the new schematics, Teensy VIN is connected to 3.3V.


    LIN transceiver min. VBB is 6V (max 27V). It won't work with 3.3V.
    CAN transceiver min. VCC is 4.5V (max 5.5V). It won't work with 3.3V.

    Connect LIN transceiver RX pull up resistor to 3.3V and not 5V. Teensy 3.6 is not 5V tolerant, applying >3.6V to any pin (except VIN) can destroy your Teensy.


    TXD to Teensy CANxTX
    RXD to Teensy CANxRX
    Could you please see if I understood your suggestions correctly and made the right changes?
    Click image for larger version. 

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  4. #4
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    looks good

    CAN RX and TX need a level converter. Best way is to use an IC like: Texas Instruments SN74LV1T34
    For 5V to 3.3V, SN74LV1T34 Vcc connects to 3.3V
    For 3.3V to 5V, SN74LV1T34 Vcc connects to 5V

  5. #5
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    Quote Originally Posted by HWGuy View Post
    looks good

    CAN RX and TX need a level converter. Best way is to use an IC like: Texas Instruments SN74LV1T34
    For 5V to 3.3V, SN74LV1T34 Vcc connects to 3.3V
    For 3.3V to 5V, SN74LV1T34 Vcc connects to 5V
    Thanks, I added the logic level converter.
    Adding my schematics here if anyone has anymore suggestions and also for documentation, it might help someone else.

    Click image for larger version. 

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  6. #6
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    One other thing, the CAN bus termination resistor is between CANH and CANL.


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