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Why use 10k pull-up resistor?
The 10k resistor (R2) is there the make sure the voltage on the pin is held at a stable high level. “High” as in a value close to the supply voltage. The reason that I chose the value 10k is that from my experience I know that 10k to 100k pull-up resistors usually work fine in almost all circuits.
What is the difference between a pull up and pull-down resistor?
A pull-up resistor connects unused input pins (AND and NAND gates) to the dc supply voltage, (Vcc) to keep the given input HIGH. A pull-down resistor connects unused input pins (OR and NOR gates) to ground, (0V) to keep the given input LOW.
Why do we need pull up and pull-down resistors?
To control the current flow, we need those pull-down or pull up resistors. A pull-up resistor allow controlled current flow from supply voltage source to the digital input pins, where the pull-down resistors could effectively control current flow from digital pins to the ground.
What are pull-up and pull down resistors?
Pull-up and pull-down resistors are frequently used in interfacing devices like interfacing a switch to microcontroller. Most of the microcontrollers have inbuilt programmable pull up/pull down resistors.So Interfacing a switch with a microcontroller directly is possible. In general, pull up resistors are often used than pull down resistors, although some microcontroller families have both pull-up and pull-down resistors.
What is a weak pull up resistor?
A low resistor value is called a strong pull-up (more current flows), a high resistor value is called a weak pull-up (less current flows). The value of the pull-up resistor needs to be chosen to satisfy two conditions: When the button is pressed, the input pin is pulled low.
What does a pull up resistor do?
In electronic logic circuits, a pull-up resistor or pull-down resistor is a resistor used to ensure a known state for a signal. It is typically used in combination with components such as switches and transistors , which physically interrupt the connection of subsequent components to ground or to VCC.
Does an output require a pull down resistor?
Another application is the I2C protocol bus, where pull-up resistors are used to enable a single pin to act as an input or an output. When not connected to a bus, the pin floats in a high-impedance state. Pull-down resistors are also used on outputs to provide a known output impedance. Power resistor.