How to calculate pull up/down resistor for floating GPIO of micro-controller pins.
Lets say for my application it is STM32L471xx series.

 

it is application specific.

as a general rule:

100k: "i'm feeling lucky today"
10k: "a day in the office"
1k: "i'm desperate".

btw, your chip has built-in PU and PD resistors.

 

it is application specific.

as a general rule:

100k: "i'm feeling lucky today"
10k: "a day in the office"
1k: "i'm desperate".

btw, your chip has built-in PU and PD resistors.

Thanks but still far away from basics.
I want to connect external pull/down resistor .

 

Thanks but still far away from basics.
I want to connect external pull/down resistor .

We don't normally calculate the values of pullup/pulldown resistors; it isn't necessary. I would suggest using some value between 5 kΩ and 50 kΩ unless there is some compelling reason to do otherwise. Usually, I use 10 kΩ.

 

I posted a solution to this question recently but cannot find it.

Here is an older thread.