PIC Musical Doorbell using PIC16F84A with Proteus Simulation

Introduction

This microcontroller project demonstrates a musical doorbell built around a PIC16F84A and a simple piezo sounder.
Using two push buttons, the system allows a user to select and play one of two pre-programmed musical tunes.
The project is implemented and tested entirely in Proteus simulation, making it ideal for learning audio generation with PIC microcontrollers.
It’s a great example of embedded systems, timer-based sound synthesis, and interrupt handling in practical electronics.
If you’re exploring DIY electronics or firmware-driven audio projects, this design offers solid hands-on value.This PIC Musical Doorbell Project uses the PIC16F84A microcontroller and a piezo sounder to generate selectable musical tunes through Timer0 interrupts, demonstrating embedded audio generation and real-time control in a Proteus simulation.The PIC Musical Doorbell Project is an embedded systems design using the PIC16F84A microcontroller to generate musical tones through a piezo sounder. The PIC Musical Doorbell Project is a simple embedded system that uses the PIC16F84A microcontroller to generate musical tones through a piezo sounder. This PIC Musical Doorbell Project demonstrates Timer0 interrupts, lookup tables, and firmware-based sound synthesis, making it suitable for learning microcontroller audio generation using Proteus simulation.

How the Project Works (Overview)

The PIC Musical Doorbell uses Timer0 interrupts to generate square-wave audio signals that drive a sounder.
When a button connected to PORTA is pressed, the microcontroller selects a corresponding tune stored in program memory.
Each tune consists of note and duration pairs, which are processed sequentially.
Pitch values are translated into timer reload values, producing accurate musical frequencies.
The result is a fully firmware-driven audio playback system without any external audio ICs.

Block Diagram / Workflow Explanation

1. Push Button Input (PORTA)

   • RA0 triggers Tune 1

   • RA1 triggers Tune 2

2. Tune Selection Logic

   • Firmware loads the starting address of the selected tune table

   • Tempo and timing parameters are initialized

3. Note Processing

   • Note code → pitch lookup table

   • Duration → delay loop counters

4. Timer0 & Interrupt Handling

   • Timer0 generates periodic interrupts

   • ISR toggles PORTB pins to create audio waveform

5. Sound Output

   • Square wave drives the sounder via PORTB

Key Features

• Two selectable musical tunes via push buttons

• Timer0-based tone generation without DAC

• Interrupt-driven sound waveform toggling

• Lookup tables for pitch and note duration

• Fully software-controlled audio synthesis

• Designed and tested using Proteus VSM

Components Used

• PIC16F84A microcontroller

• Piezo sounder / speaker

• Push buttons (2×)

• Resistors (pull-ups, current limiting)

• External crystal oscillator (1 MHz)

• Capacitors for oscillator stability

Applications

• Musical doorbells

• Embedded audio demos

• Microcontroller music players

• Educational projects for timers and interrupts

• DIY sound generation systems

Explanation of the Code (High-Level)

The firmware begins by configuring PORTB as output and setting up Timer0 with a prescaler for tone generation.
The main loop continuously polls the push buttons on PORTA.
Once a button is detected, the corresponding tune pointer and tempo are loaded.

Each note is fetched from program memory using computed jumps via PCL and PCLATH.
Pitch values are converted using a lookup table, and Timer0 reload values control frequency.
An interrupt service routine toggles PORTB pins on every Timer0 overflow, producing the audible square wave.
The tune ends when a termination flag is detected, returning the system to idle state.

Source Code

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              LIST    p=16F84 ; PIC16F844 is the target processor

              #include "P16F84A.INC" ; Include header file

              CBLOCK 0x10   ; Temporary storage
              tempo
              tptrl
              tptrh
              note
              length
              pitch
              temp              
              dl1
              dl2              
              ENDC

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Complete Source Code

Proteus Simulation

In Proteus VSM, the PIC16F84A runs in real time while Timer0 generates audio-rate interrupts.
Pressing either push button immediately starts playback of the selected tune.
The sounder output reflects accurate pitch and timing based on the firmware logic.
This simulation closely mirrors real hardware behavior, making it excellent for testing and learning.

Conclusion

This PIC Musical Doorbell project is a compact yet powerful example of audio synthesis using a PIC microcontroller.
It demonstrates timers, interrupts, lookup tables, and structured firmware design in a clear, practical way.
Whether you’re learning embedded systems or building fun DIY electronics, this project delivers strong educational value with minimal hardware.

Complete File

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PIC Musical Doorbell using PIC16F84A with Proteus Simulation