Go Down

Topic: Pull Up/Pull Down Resisters (Read 2050 times) previous topic - next topic

stilwalli

Hello Experts,

I just started my journey with Arduino.

I got hold of starter kit and did couple of exercises like Get to know your tools, Spaceship interface, Love-o-Meter etc. The circuits used in these exercises connect some resister to ground and some to 5v.

I am trying to understrand, how do we decide if we have to connect resister to ground or 5v. Also known as Pull Up/Pull Down resister.

I am not able to get the concept of using one in our circuits!!

-Thanks

stilwalli

Why is switch connected to resister in some of the circuits? How do we decide, if we need such pull up or pull down resistors?

Shashank

JimboZA

It's your choice: it depends if you want the line to go high when button is pressed (pulled down most of the time) or go low when pressed (pulled up most of the time). It's mostly a matter of how you want your logic to work.

That said:


  • It's easier to implement the Arduino built-in resistors, and those are only pullUP

  • It seems the prevailing wisdom is to have pullups rather, and then only a ground wire to the sensor rather than a 5V line in case of shorts.

Johannesburg hams call me: ZS6JMB on Highveld rep 145.7875 (-600 & 88.5 tone)
Dr Perry Cox: "Help me to help you, help me to help you...."
Your answer may already be here: https://forum.arduino.cc/index.php?topic=384198.0

fungus


Hello Experts,

I just started my journey with Arduino.

I got hold of starter kit and did couple of exercises like Get to know your tools, Spaceship interface, Love-o-Meter etc. The circuits used in these exercises connect some resister to ground and some to 5v.

I am trying to understrand, how do we decide if we have to connect resister to ground or 5v. Also known as Pull Up/Pull Down resister.

I am not able to get the concept of using one in our circuits!!


Both will work, but pullup resistors are much safer (electrically speaking). Less chance of short-circuits. They're the best choice.

Arduinos have built-in pullup resistors. No need for external ones.

Just use "pinMode(pin, INPUT_PULLUP);", job done.

Advanced Arduino

Hackscribble

Hackscribble.  Writing about making things
hackscribble@outlook.com

Grumpy_Mike


Go Up