• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 30 subscribers
  • Views 793 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.

Original question:

TMS570LC4357: GIO functionality

TMS570LC4357: GIO in high state during reset

ahmad muaz abd muttalib26
Prodigy 40 points
Part Number: TMS570LC4357

I have this weird behavior where my external GIO in high state during reset (where I push on-board reset button).
P/S:
The on-board LED seems to work just fine (it turn off during reset).

can someone explain to me?
didn't the GIO in impedance(input) state during reset?

  • 0
    TI__Mastermind 21425 points

    Hello,

    During Reset all I/Os are configured as inputs and Default Pull State is applied.

    Default Pull States are defined in Datashet, Section 4.2 Terminal functions.

    Best regards,

    Miro

  • 0 in reply to Miro
    Prodigy 40 points

    During reset, all I/O is in input state.
    So, based on the table, when reset occur, the GIO should be in input with pulldown state. right?

    my question follows, does in this state, the GIO will give out some current or not at all?

    because I connect the GIO to basic transistor switching circuit, and the transistor switch on.

    I've tried the following scenario:
    1)  Use 100kOhm base resistor as to limit the current into the transistor.
    2)  make external pulldown resistor to ground.

    but my transistor seems to switch on when I push the reset button and bear in mind, that the on-board LED seems to turn off as expected.
    is there something I missing?

    Best regards,
    Muaz,

  • 0 in reply to ahmad muaz abd muttalib26
    TI__Mastermind 21425 points
    Hello,
    Which GIO you are observing?

    Best regards,
    Miro
  • 0 in reply to Miro
    Prodigy 40 points

    Hello,

    the GIO effected are as below.
    1) GIOA_4
    2) GIOA_2
    3) GIOB_1

  • 0 in reply to ahmad muaz abd muttalib26
    TI__Mastermind 21425 points
    Hello,
    I made some tests, all GIOs are low during reset (while reset button is pushed). GIO is set to input while nPORRST is low (while reset button is pushed) and immediately after nPORRST goes high. Then application software takes care on MCU. Disconnect all external circuitry before testing.

    Best regards,
    MIro
  • 0 in reply to Miro
    Prodigy 40 points

    Hello,

    I've also done some testing,

    1) while there is no circuit connected to pin, it turn OFF during reset.

    2) while the pin is connected to LED and  resistor, the behavior is as expected, OFF during reset.

    3) when the pin is connected to transistor,  the transistor is ON during reset.

    I suspected there is some leakage current flow from the pin to my board during reset OR my circuit is wrong completely. The weird thing is, the same circuit used in other micro controller seems to work as expected which turn OFF during reset. Only in this board the behavior is unexpected.

    never mind, thanks for the help anyway.

    p/s: Because during flash the CPU while reset, my circuit turn ON every time I flash new code. So, i've just added some external switch to turn off any power to my board temporarily during flash.