Which port of 8051 does not have internal pull-up resistor?

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Which port of 8051 does not have internal pull-up resistor?

What are the features and functions of Port 0 in 8051? Construction: Port 0 has a D-type latch, unidirectional buffer, and 2 FETs at each pin. It does not have an internal pull-up resistor. An external pull-up resistor is needed when Port 0 is defined as an output port.

Why external pull-up resistance is used in I2C?

Why is a pull-up resistor used in I2C? Because there are only 2 logic level outputs from I2C, Low and open circuit. The default condition is all chips on the line are in open circuit mode, and the pull-up resistor makes the line high. The master chip can send an address signal to one of the chips on the line.

Why we connect pull-up resistor with 8051?

To ensure the values of an I/P is always in a known state, pull up and pull-down resistors are used. The main function of pull-up and pull-down resistors is that the pull up resistor pulls the signal to high state unless it is driven low; and, a pull-down resistor pulls the signal to low state unless it is driven high.

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Why port 0 does not have pull-up resistor why external pull-up resistor is needed for port 0?

Since there is no internal pull-up resistor for Port0. It’s tri-state and basically tri-state is a condition of ambiguity where we can’t predict it’s logic level. In order to remove the condition of ambiguity, we add external pull-up resistor to it.

What is a pull-up pull down resistor?

Pull-up Resistor Summary 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 we use pull-up resistor?

In electronic logic circuits, a pull-up resistor or pull-down resistor is a resistor used to ensure a known state for a signal. For a switch that connects to ground, a pull-up resistor ensures a well-defined voltage (i.e. VCC, or logical high) across the remainder of the circuit when the switch is open.

How do you determine the value of a pull-up resistor?

A rule of thumb is to use a resistor that is at least 10 times smaller than the value of the input pin impedance. In bipolar logic families which operate at operating at 5 V, the typical pull-up resistor value is 1-5 kΩ. For switch and resistive sensor applications, the typical pull-up resistor value is 1-10 kΩ.

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Why pull-up resistors are used?

In electronic logic circuits, a pull-up resistor or pull-down resistor is a resistor used to ensure a known state for a signal. A pull-up resistor effectively establishes an additional loop over the critical components, ensuring that the voltage is well-defined even when the switch is open.

Why we need pull up 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.

Why pull-up resistor is connected to a microcontroller?

Pull-up resistors are used to solve the dilemma for the microcontroller by pulling the value to a logical high state, as seen in the follow figure. Without the pull-up resistor, the MCU’s input would be floating when the switch is open and pulled down to a logical low only when the switch is closed.

What is the RESET pin on an 8051 microcontroller?

Pin 9:- As explained before RESET pin is used to set the 8051 microcontroller to its initial values, while the microcontroller is working or at the initial start of application. The RESET pin must be set high for 2 machine cycles. Pins 1 – 8:- Known as Port 1. Unlike other ports, this port does not serve any other functions.

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What is the difference between AT89C51 and 8051 microcontroller?

The only difference between the original 8051’s architecture and the AT89c51’s architecture is that the latter has 4KB of on-chip programmable flash memory. This allows for faster development since the flash memory can be erased in a few seconds.

What are the pins of port0 on a microcontroller?

Port0 uses the Pins 32 to 39. Each pin is bidirectional Input /Output but without internal pull – up resistors. So we need to use an external pull-up before using Port0 as Input /Output. Pin 40 is the power supply pin of the 8051 Microcontroller.

What is the ale pin on the AT89C51?

In AT89C51, the lower 8 bits of the 16-bit address bus are multiplexed with the data bus. To separate these 8 bits, the ALE pin is kept high. It is an output pin that is used when we are connecting to external extra memory chips. stands for Program Pulse Input and is used when we are programming the flash memory of the AT89C51.