Image making a digital circuit where a push button is required to turn on an LED.
So what exactly is a pull-up resistor?
How does it work, and how do you use one?
Image Credit:Tomi Knuutila/Flickr
What Is a Pull-up Resistor?
Setting a default state of all input pins is important to avoid random signals generated during its floating state.
Pull-up resistors are typically used in digital circuits usingmicrocontrollers and single-board computers.
However, disengaging the switch wont necessarily stop the input pin from sending such signals.
This is because cutting the connection through a switch means its no longer connected to anything but air.
To avoid shorting the pull-up voltage, youll need to use a resistor.
The amount of resistance will depend on the logic throw in your circuit is using.
The logic family that your circuit uses will dictate the resistance value your pull-up resistor will need.
There are several types of logic.
To calculate the correct resistor value, youll need three values.
you could use pull-up resistors if the digital circuit uses switches and sensors as input devices.
Also, pull-up resistors will only be effective if the input pins are connected to ground.
If the input pins are connected to VCC, you might want to use pull-down resistors instead.
To use a pull-up resistor, youll need to locate the input line that connects to an input gear.
Once located, youll want to calculate how the value of your resistor using the formula discussed earlier.
You now know what a pull-up resistor is and how to use one.
