CURRENT CONSUMPTION BY INTERNAL PULL UP

[zuhaib]

I am connecting a normal tactile switch with the NRF52833 GPIO such that one end of switch goes to the ground and another on the gpio.

Now when the switch is pressed my gpio will read a low logic ,now if I pull up the gpio using internal pull up.

what are the scenarios?

HOW MUCH CURRENT POWER WILL BE WASTED BY THIS INTERNAL PULLUP RESISTOR?

will the current flow only when I press the button

or there will be any other losses while i am not pressing the switch and the gpio is just pulled up by internal circuitry?

[Bendik Heiskel]

Hi,

When using the internal pullup there will not be any leakage current. Current will only flow when the button is pushed, this current will be equal to VDD/13k.

 

Best regards,

Bendik

[zuhaib]

what if I dont pull up the the gpio ? and try the same thing? what is the minimum level of voltage for a logic 0 and logic 1 for the gpio?

[Bendik Heiskel]

zuhaib said:

what if I dont pull up the the gpio ? and try the same thing?

If the GPIO pin is not pulled up it will be in a undefined state when the button isn't pressed This will lead to unexpected behavior and may lead to a higher current draw, if for example a interrupt is used. I would recommend using a pull up for the button in this configuration.

zuhaib said:

what is the minimum level of voltage for a logic 0 and logic 1 for the gpio?

For logic 0 the voltage range is VSS to 0.3*VDD, and for logic 1 0.7*VDD to VDD.

More information about the GPIO peripheral can be found here:

https://infocenter.nordicsemi.com/topic/ps_nrf52833/gpio.html?cp=4_1_0_5_7_2#unique_1576379008

[hmolesworth]

You can cheat; only enable the pull-up then read the pin input and see if it is high (switch open) or low (closed).  Then disable the pull-up.

[zuhaib]

exactly thanks for the answer i was working and done some research last night and i also think of the same solution