Teensy 3.6 CAN LIN Board

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alborz

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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:
schematic.jpg



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?
 

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

alborz said:
  • 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)?
Click to expand...
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.

alborz said:
  • 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?
Click to expand...
TXD to Teensy CANxTX
RXD to Teensy CANxRX
 
Last edited:
HWGuy said:
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
Click to expand...

Could you please see if I understood your suggestions correctly and made the right changes?
schematic.jpg
 
HWGuy said:
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
Click to expand...

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.

schematic.jpg
 
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