• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 82 subscribers
  • Views 1623 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.

TMS320F28335: Unused GPIO pins.

WENBO LI
Intellectual 440 points
Other Parts Discussed in Thread: TMS320F28335

On TMS320F28335 processor, for those unused GPIO pins, shall they be connected to GND directly or through a resistor? Is a 2K ohm resistor ok to pull down?

If the unused GPIO is connected to GND directly, there is a concern that if the software accidently configures the pin to an output at development stage, then it might cause a damage to the pin or DSP. Maybe it's safer to use a pull-down resistor to connect the unused GPIO to GND. (I prefer pull-down than pull-up) The question is: what's the best value for the pull-down resistor? Any suggestions?

Thank you.

 

  • 0
    Expert 2420 points

    Hi!

    I suggest to not connect unused pins. Just let them free. The internal pull up resistors will keep the inputs in a defined hi-state. Just keep sure that your unused pins have enabled pull-ups (gpio0-11 do not have the pull-ups enabled after reset, just check the datasheet).

    Best regards,
    Edwin Krasser

  • 0
    TI__Guru 55700 points

    I would recommend grounding the unused pins with 1K resistor.

    Regards,

    Manoj

  • 0 in reply to Manoj Santha Mohan
    Expert 2420 points

    If you do so, you should disable every pull up resistor (if this is supported by the processor). You can expect 100 uA per grounded pull down. Hence I suggested to leave unused pins unconnected. The internal pull up resistors do everything we need.
    We use the c2000 since their beginning in 2002 (f2810/12, f2808, f28335, c28346: anything but piccolo) and we never grounded unused pins because the internal pull ups care for a defined logic level.

    Best regards,
    Edwin Krasser