Offline ESP32 TTS: Build a Self-Contained Talking Device 🚀

Turn your ESP32 into a fully offline text-to-speech device — no cloud needed. A tiny, reliable, and customizable voice system for your IoT and embedded projects.

🧠 Why Build an Offline Text-to-Speech ESP32?

Most text-to-speech systems rely on cloud APIs. They’re great — until your device is offline, remote, or needs instant audio feedback without latency.

This project solves that by giving the ESP32 its own onboard voice, powered by lightweight LPC-encoded speech data. That means:

• No Wi-Fi dependency
• Instant audio output
• Extremely low cost
• Expandable vocabulary

Perfect for automation, alerts, accessibility devices, and educational prototypes

If you want a talking IoT system that works anytime, anywhere, offline TTS is the way to go.

🔊 What You’ll Build

• A compact voice module based on:
• ESP32 development board
• PAM8403 or similar mini amplifier
• Small 8Ω speaker
• Talkie-based LPC speech engine

Once set up, the ESP32 can say predefined words or sentences based on serial input, user commands, or sensor-driven events.

🛠️ Wiring Overview:

• ESP32 DAC pin (GPIO25 or GPIO26) → PAM8403 Audio In
• PAM8403 Out → Speaker terminals
• PAM8403 VCC → 5V
• PAM8403 GND → ESP32 GND

That's it — just a handful of connections.

🧩 How the Offline TTS Works

The magic happens through LPC (Linear Predictive Coding) – the same technique used by early talking toys and classic embedded speech systems.

Here’s the process:

You send a sentence to the ESP32 through Serial or a programmatic trigger.

• The program splits the sentence into words.
• Each word matches an LPC-coded audio sample stored in flash memory.
• The DAC outputs the audio waveform.
• The amplifier + speaker plays recognizable human-like speech.
• It’s lightweight, fast, and ideal for microcontrollers.

💻 Code Overview

Below is a simplified structure of how speech playback works:

#include <Arduino.h>
#include "Talkie.h"
#include "Vocab_US_Large.h"

Talkie voice;

void setup() {
  Serial.begin(115200);
  Serial.println("Offline TTS Ready!");
}

void loop() {
  if (Serial.available()) {
    String input = Serial.readStringUntil('\n');
    input.toLowerCase();

    if (input == "hello") {
      voice.say(spHELLO);
    } else if (input == "system ready") {
      voice.say(spSYSTEM);
      voice.say(spREADY);
    } else {
      Serial.println("Word not in vocabulary");
    }
  }
}

You can add as many words as your flash memory allows, making the system fully customizable.

🌟 Why Developers Love This Project

This type of offline TTS module is perfect for:

✔ Smart home automation

“Door open,” “Lights on,” or “Water tank full.”

✔ Industrial / IoT status alerts

Voice notifications for sensors, safety systems, or machine states.

✔ Accessibility devices

Reading out short prompts for visually impaired users.

✔ Kids’ STEM education

Build your own talking gadget — the engagement factor is huge.

✔ Retro-tech projects

Talkie’s LPC voice has a nostalgic charm that fits vintage builds.

🚀 Ways to Take This Project Further

Once your basic TTS module is running, you can expand it into:

• A talking weather station
• A voice-enabled alarm system
• A sensor-driven notification panel
• A robot with spoken feedback
• A voice menu system with buttons or a web UI

You can even create your own LPC word files for custom names, alerts, and phrases.

🧭 Final Thoughts

ESP32 Text to Speech Offline TTS unlocks new possibilities for embedded systems — especially when you want ultra-reliable speech without the internet. With just an ESP32, a small amp, and a speaker, you can give your projects a real personality.

If you’re looking for a fun, practical, and useful build, this is one of the most satisfying ESP32 projects you can publish or expand on.