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⚙️ 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.

AT89C51 UP DN COUNTER 7 Segment

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.

📖 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

🔑 Keywords

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

🛠️ 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

🛠️ 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
}

📦 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

🚀 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.

🤝 Contributing

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

📧 Contact

For questions or assistance, contact me at [email protected].

Give this repository a ⭐ if you find it helpful!