Why the pin 2 could get HIGH value?

Other Hardware General Electronics
1

I am a fresh man about the arduino, today i read the Input Pull-Up Resister chapter document at here: Digital Input Pull-Up Resistor | Arduino Documentation | Arduino Documentation

I am confused about the Circuit at that page, because i noticed that pin 2 hasn't connect to the pin 5V of the Ardunio Uno board so how can the pin 2 read HIGH ? Mmm,just because the type of pin 2 is Input Pull-Up? Thx

2

Yes. Below taken from the 328P datasheet.

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image933×541 14.9 KB

When you enable the internal pull-up resistor, the FET in the right top connects the resistor Rpu to Vcc (5V / 3.3V depending on Vcc).

3

Hello
Take a view here to gain the knowledge.

Many thanks to LarryD

Have a nice day and enjoy coding in C++.
Дайте миру шанс!

1 Like
4

Well it's not so much that pin 2 is an specific type, all the pins can be made to turn on their pull up resistor by a software command, normally done in the setup function in your code.
Note that example uses

pinMode(2, INPUT_PULLUP);

For a full discussion about inputs see
http://www.thebox.myzen.co.uk/Tutorial/Inputs.html

By the way I moved your post away from where you posted, which is meant to be about installing the IDE software.

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