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16. TTS (Text-to-Speech)

This example demonstrates how to use the TTS (Text-to-Speech) module to make PiCrawler speak. It supports two engines: Piper (high-quality neural TTS) and Espeak (lightweight classic TTS). Type any text and the robot will read it aloud.

Run the Code

cd ~/picrawler/examples
sudo python3 16_tts.py

After running the program, the engine type and model are displayed. Type any sentence and press Enter — the robot speaks it. Type quit to exit, or press Ctrl+C.

Code

Note

You can Modify/Reset/Copy/Run/Stop the code below. But before that, you need to go to source code path like picrawler\examples. After modifying the code, you can run it directly to see the effect.

#!/usr/bin/env python3
from robot_hat.tts import Piper, Espeak

# Text-to-Speech demo using robot_hat TTS module
# Press Ctrl+C to exit

# Set USE_PIPER=True for high-quality neural TTS (Piper), False for Espeak
USE_PIPER = True

# Piper model: "en_US-ryan-low" (English), "zh_CN-huayan-x_low" (Chinese)
TTS_MODEL = "en_US-ryan-low"

def main():
    print("=== PiCrawler Text-to-Speech Demo ===")

    if USE_PIPER:
        print(f"Engine: Piper ({TTS_MODEL})")
        tts = Piper(model=TTS_MODEL)
    else:
        print("Engine: Espeak")
        tts = Espeak()

    print("Type text to speak, or 'quit' to exit")
    print()

    try:
        while True:
            text = input("Text to speak: ").strip()
            if text.lower() == 'quit':
                break
            if text:
                print(f"Speaking: {text}")
                tts.say(text)
    except KeyboardInterrupt:
        print("\nExiting...")

if __name__ == "__main__":
    main()

How it works?

Two TTS Engines Available
```
from robot_hat.tts import Piper, Espeak
```
The robot_hat package provides two TTS engines:
- Piper: A neural-network-based engine that produces natural, high-quality speech. Requires a voice model file.
- Espeak: A lightweight, rule-based engine that runs on minimal resources.
Choosing the Engine and Model
```
USE_PIPER = True
TTS_MODEL = "en_US-ryan-low"
```
Set USE_PIPER to True for Piper or False for Espeak. When using Piper, TTS_MODEL selects the voice. Common models include:
- "en_US-ryan-low" — American English male voice
- "zh_CN-huayan-x_low" — Chinese female voice
Creating the TTS Instance
```
if USE_PIPER:
    tts = Piper(model=TTS_MODEL)
else:
    tts = Espeak()
```
Based on the USE_PIPER flag, the appropriate engine is instantiated. Both engines share the same say() interface, so switching engines requires no other code changes.

The Input Loop

while True:
    text = input("Text to speak: ").strip()
    if text.lower() == 'quit':
        break
    if text:
        print(f"Speaking: {text}")
        tts.say(text)

The program prompts you for text:

Type any sentence and press Enter to make the robot speak.
Type quit to exit the loop.
Press Ctrl+C at any time to interrupt.

Contrast with STT

This lesson is the companion to 15. STT (Speech-to-Text). Together, STT (speech recognition) and TTS (speech synthesis) form the input and output halves of a voice interface for PiCrawler.