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Current from GPIO to GPIO

Anonymous
Anonymous

Hi,

 

I would like to ask a question GPIO.

 

Is it allowed for current to flow from one GPIO pin to another? I have experimented with GPIO, and found there is no problem when:

 

 

GND

Vcc

GPIO high

GPIO to GND

No

GPIO low

No

Vcc to GPIO

 

 

However, am I supposed to let current flow from one GPIO pin to another, for example, GPIO 1 (high) → GPIO 2 (low)? I don’t know the electronics inside, is this legal? Can there be any damage to the chip or circuit?

 

    

 

Zheng

  • 0
    TI__Expert 5475 points

    Hi,

    I am not sure how this could happen unless there is a short on the board.

    It is not a good idea as there could be 50+mA of current from VCC->GPIO->GPIO->VSS.

    The power dissipation will cause heating which can be a reliability issue.

    That said, it is allowable but certainly not a good idea, especially if the frequency of duration is large.

    Best regards,

    Zegeye

  • Anonymous
    0 Anonymous in reply to Zegeye Alemu

    Zegeye,

    Zegeye said:

    It is not a good idea as there could be 50+mA of current from VCC->GPIO->GPIO->VSS.

    Should I limit the current by placing resistor between GPIO pins? For example, if I place 3K Ohm resistor between GPIO 1 (high) and GPIO 2 (low), can the current be calculated as

    3.3V / 3K = 1.1 mA

    ?

    Is this a common practice?

     

     

    Zheng

     

  • 0 in reply to Anonymous
    TI__Expert 5475 points

    Hi,

    Why do you want to short it?

    Are you trying to drive one GPIO from another ...? Are you shorting it and still driving a load ...?

       -----||||||||||------ Load

        |

      3K Resistor

        |

      -----||||||||||------ Load

    I was trying to draw your arrangement above.

    Anywary, you need to check the timing carefully. The driver must be able to drive Vih and Vil.

    Best regards, Zegeye

     

  • 0 in reply to Zegeye Alemu
    TI__Expert 5475 points

    Hi again,

    If your use case is where one GPIO is driving another GPIO (one is configured as Output and another as Input), then you should be fine.

    Best regards,

    Zegeye

  • Anonymous
    0 Anonymous in reply to Zegeye Alemu

    Zegeye,

    I have got the solution. Current between GPIO can be avoided.

     

    Zheng