INPUT_PULLUP vs Regular Pull Up?

What benefits does using the built in INPUT_PULLUP have instead of a physical pull up resistor outside the board?

Volume3k:
What benefits does using the built in INPUT_PULLUP have instead of a physical pull up resistor outside the board?

The internal one is free and requires no soldering.

Volume3k:
What benefits does using the built in INPUT_PULLUP have instead of a physical pull up resistor outside the board?

External resistor could be used as a pull-down resistor. Depends on what you want.

Paul

You can control the value of an external resistor, either using a larger ("weaker") value to draw less current or a smaller ("stronger") value that is more resistant to interference.

The Atmega328P data sheet says that the value of the internal pull-up is 20k to 50k; there is no value such as typical. What is the reason for the value not to be a fixed one?

GolamMostafa:
The Atmega328P data sheet says that the value of the internal pull-up is 20k to 50k; there is no value such as typical. What is the reason for the value not to be a fixed one?

Manufacturing tolerance.

Personally, if power supply or current sinking isn’t an issue, i use 4k7 as pull-up (if i need externals), to increase the noise immunity of that input pin.

In a well designed circuit, about 90% of the time - internal pull-up is fine.

The internal pullup can be easily disabled.