• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 31 subscribers
  • Views 2446 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TMS570LS1114: External Pull Up CAN TX / RX

Sebastian Schöler
Prodigy 230 points

Part Number: TMS570LS1114

Dear support team,

I just came across the following note, considering the CAN TX / RX signals in the technical reference manual for the Hercules MCU. 

Note: When CAN_RX pin is connected to a CAN transceiver, an external pullup resistor has to be

used to ensure that the CAN bus will not be disturbed (for example, while the DCAN module is

reset).

Same note goes for the CAN_RX pin.

I just wanted to understand, why these resistors have to be added, when there exists already internal pullup resistors in the MCU itself against disturbances? I am especially interested in the reason to add this external resistor for the RX line.  

Thank you and kind regards

Sebastian

  • 0
    TI__Guru**** 201546 points

    Hello Sebastian,

    I don't think the pull-up resistor is required for DCAN bus (CANH and CANL) and CAN_TX/RX signals. TIOC and RIOC registers are used to configure CAN_TX and CAN_RX as GIO pins, and this note is for GIO mode.