⚙️ 8051 Push Button

This repository guides you to learn about digital input reading using an 8051 Microcontroller. The program is written in Assembly language and well-commented to ensure clarity. To read the digital input, two tactile push button switches are connected to I/O pins.

We will explore two modes:

1. Normally High, low when pressed.
2. Normally Low, high when pressed.

Two circuit configurations with Pull-Up and Pull-Down techniques are demonstrated below.

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📖 Overview

This project uses push buttons to read digital input on an AT89C51 microcontroller. It covers essential concepts of switch debouncing to ensure reliable button presses. The repository includes:

• Assembly Code
• Precompiled HEX file
• Proteus Simulation Circuit

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🔑 Keywords

AT89C51 Microcontroller | Push Button Debounce | Assembly Language | Proteus Simulation | Microcontroller Programming

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🛠️ Hardware & Circuit Information

Component	Description
AT89C51 Microcontroller	Controls the system and reads the input from push buttons
Push Buttons	Two tactile switches configured with pull-up or pull-down
Resistors	Current-limiting for protecting input pins and the MCU
Capacitor	For hardware debouncing (optional)
Power Supply	5V DC for the microcontroller circuit

Circuit Configuration: Pull-Up and Pull-Down Techniques

1. Pull-Up Configuration: The input pin is connected to a high voltage (logic HIGH) via a resistor, and pressing the button connects the pin to ground (logic LOW).

   Pull-Up Circuit:

   VCC ----[R]---- Input Pin
                    |
                  Switch
                    |
                   GND
   

2. Pull-Down Configuration: The input pin is connected to ground (logic LOW) via a resistor, and pressing the button connects the pin to a high voltage (logic HIGH).

   Pull-Down Circuit:

   GND ----[R]---- Input Pin
                    |
                  Switch
                    |
                   VCC
   

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🛠️ Switch Debounce

When you press a mechanical switch, the contacts may bounce before stabilizing, leading to multiple readings of a single press. This effect is called bouncing, and it can cause unreliable behavior in your microcontroller program.

Why is Debouncing Necessary?

Without debouncing, a single press may register multiple times due to rapid bouncing. This can cause erratic behavior in your system.

Techniques for Debouncing

1. Hardware Debouncing: Use a capacitor across the switch contacts to smooth out the bouncing effect.

2. Software Debouncing: Add a small delay in your code to allow the switch to stabilize before reading the final state.

Example of Software Debouncing in C:

#define DEBOUNCE_DELAY 50 // 50 milliseconds

int debounceSwitch(int pin) {
  if (digitalRead(pin) == HIGH) {   // if the switch is pressed
    delay(DEBOUNCE_DELAY);          // wait for the debounce period
    if (digitalRead(pin) == HIGH) { // check the state again
      return 1;                     // switch is pressed
    }
  }
  return 0;                         // switch is not pressed
}

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📦 Repository Contents

File	Description
AT89C51_Push_Button.asm	Assembly code for reading push buttons
AT89C51_Push_Button.hex	Precompiled HEX file for microcontroller programming
Proteus_Push_Button_Simulation.pdsprj	Proteus simulation file for testing the circuit
Screenshots	Images of the simulation and real hardware testing

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🚀 How to Use

1. Clone the Repository:

   git clone https://github.com/your-repo/8051-Push-Button.git

2. Compile the Assembly Code: Open the AT89C51_Push_Button.asm in an 8051 IDE, and compile it to generate the HEX file.

3. Simulate in Proteus: Open Proteus Design Suite and load the provided simulation file.

4. Program the Microcontroller: Upload the HEX file to your AT89C51 microcontroller and test the circuit with real hardware.

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🤝 Contributing

We welcome contributions! Feel free to submit pull requests or open issues to suggest improvements.

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📧 Contact

For questions or assistance, contact me at mostofa.melab@gmail.com.

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Give this repository a ⭐ if you find it helpful!