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CC2530 ports pull-up and pull-down

adarsh.pll
Intellectual 580 points

In CC253x user guide , page 79 the following statements are confusing. Does it mean that when no internal pull-up or pull-down is configured. All the ports need to be pull up or down specifically?

7.1 Unused I/O Pins
Unused I/O pins should have a defined level and not be left floating. One way to do this is to leave the pin
unconnected and configure the pin as a general-purpose I/O input with pullup resistor. This is also the
state of all pins during and after reset (except P1.0 and P1.1, which do not have pullup or pulldown
capability). Alternatively, the pin can be configured as a general-purpose I/O output. In either case, the pin
should not be connected directly to VDD or GND, in order to avoid excessive power consumption

Thanks in Advance

Adarsh

  • 0
    TI__Genius 16570 points

    Hi,

    no what the sentence says is that in order to avoid excessive power consumption, the un-used pins should not be connected to external VDD or GND via a pull up or pulld down respectively.

    For the pins which have pulls, you can either select them as GPIO input and configure the pulls as pull up (which is the same value of those pins at reset) or as output and set them to 0.

    For P1.0 and P1.1, since they don't have internal pulls, a best practice would be to configure them as GPIO output and set them to 0.

    Hope this answers your question.

    Thanks,

    TheDarkSide

  • 0 in reply to TheDarkSide
    Intellectual 580 points

    Thanks for prompt response.

    But i need to use P1.0 as input. Then what should be the case? Externally giving pull-up will be the only solution left probably?

    Regards

    Adarsh

  • 0 in reply to adarsh.pll
    TI__Genius 16570 points

    If you are just using P1.0 as input, then no problem since that pin does not have internal pull ups, you just configure it as input and let the external device driving it (and you won't have any extra leakage).

    However, just so you know as a generic design recommendation, P1.0 and P1.1 are the only pins capable of a high output drive so typically when we use them we use them as output.

    Just for your information.

    Thanks,

    TheDarkSide