Table of Contents

Walkie Talkie

Author: Scutaru Alexandru, 333CD

Introduction

This project consists of two portable wireless communication devices built around the ESP32-WROOM-32 microcontroller, communicating via the ESP-NOW protocol over 2.4GHz.

Each device captures voice through an analog microphone module, compresses the audio signal using the ADPCM (Adaptive Differential Pulse-Code Modulation) algorithm, and transmits it in real time to the paired device. Transmission is initiated manually by pressing the Push-to-Talk button.

Each device features an OLED display showing signal strength and battery level. Audio playback is handled through a PAM8403 amplifier driving a 4Ω 3W speaker, using the ESP32's onboard DAC. The system is powered by a LiPo battery with built-in protection circuit.

The idea started from the desire to implement a real-time audio communication.

Descriere generală

Hardware Design

Bill of Materials

Component Model Quantity Purpose
Microcontroller ESP32-WROOM-32 DevKit V1 2 Main processor, ESP-NOW communication, ADC, DAC, GPIO
Display OLED 0.96” I2C SSD1306 2 Shows battery level - Received Signal Strength Indicator
Microphone Analog microphone module with AGC 2 Voice capture, analog signal output to ADC
Audio amplifier PAM8403 3.6-5V 2x3W 2 Amplifies DAC output signal to drive the speaker
Speaker 40mm 3W 4Ω 2 Audio playback of received voice
Battery LiPo 3.7V 2000mAh with protection 2 Portable power supply
Charging module TP4056 with protection USB-C 2 Battery charging and undervoltage protection
Breadboard 830 points 2 Prototyping platform
Jumper wires M-M + M-F 1 set Connections between components
Resistors 100kΩ 4 Voltage divider for battery level reading via ADC
Capacitor Electrolytic 1000µF 2 Decoupling capacitor for ESP32 current spikes
Tactile buttons 6mm momentary 4 PTT (x2), Volume(x2)
LEDs red + green 4 TX status (red) and RX status (green) per device