How to Use SparkFun VoiceBox Shield: Examples, Pinouts, and Specs

The SparkFun VoiceBox Shield (Manufacturer Part ID: DEV-10661) is an Arduino-compatible shield designed to add voice recognition and playback capabilities to your projects. This shield is powered by the SpeakJet IC, a versatile speech synthesis chip capable of generating speech, sound effects, and tones. With this shield, users can create interactive systems that respond to voice commands or provide audio feedback.

• Voice-controlled robotics
• Talking devices or interactive displays
• Audio feedback systems for accessibility
• Home automation with voice commands
• Educational projects for learning speech synthesis

The following table outlines the key technical details of the SparkFun VoiceBox Shield:

The SparkFun VoiceBox Shield connects to an Arduino board and uses the following pins:

1. Attach the Shield to an Arduino: Align the pins of the VoiceBox Shield with the headers on your Arduino board and press gently to secure the connection.
2. Connect an Audio Output:
   • For a speaker: Connect an 8-ohm speaker to the Speaker+ and Speaker- terminals.
   • For headphones or external amplifiers: Use the 3.5mm audio jack.
3. Power the System: Power the Arduino via USB or an external power source. The shield will draw power from the Arduino.
4. Upload Code: Write and upload a sketch to the Arduino to send commands to the SpeakJet IC via UART.

• Speaker Selection: Use an 8-ohm speaker for optimal performance. Avoid using speakers with lower impedance, as they may overload the circuit.
• Volume Control: The SpeakJet IC does not have built-in volume control. Use an external amplifier with volume adjustment if needed.
• UART Configuration: Ensure the Arduino's UART baud rate matches the SpeakJet's default baud rate (9600 bps).
• Avoid Overloading: Do not send commands to the SpeakJet IC too quickly, as it may not process them correctly. Add delays between commands if necessary.

Below is an example sketch to send a simple command to the SpeakJet IC to produce a sound:

// Include the SoftwareSerial library for communication with the SpeakJet IC
#include <SoftwareSerial.h>

// Define RX and TX pins for SoftwareSerial
#define RX_PIN 2
#define TX_PIN 3

// Create a SoftwareSerial object
SoftwareSerial speakJetSerial(RX_PIN, TX_PIN);

void setup() {
  // Initialize the SoftwareSerial communication at 9600 baud
  speakJetSerial.begin(9600);
  
  // Send a simple command to the SpeakJet IC to produce a sound
  // The command below plays a "Hello" sound using predefined phonemes
  speakJetSerial.write(0xC1); // Reset SpeakJet
  delay(100); // Wait for reset to complete
  speakJetSerial.write(0xF0); // Start command
  speakJetSerial.write(0x4A); // Phoneme: "H"
  speakJetSerial.write(0x45); // Phoneme: "E"
  speakJetSerial.write(0x4C); // Phoneme: "L"
  speakJetSerial.write(0x4C); // Phoneme: "L"
  speakJetSerial.write(0x4F); // Phoneme: "O"
  speakJetSerial.write(0x20); // End command
}

void loop() {
  // No actions in the loop for this example
}

1. No Sound Output:

   • Ensure the speaker is properly connected to the Speaker+ and Speaker- terminals.
   • Verify that the 3.5mm audio jack is not in use simultaneously with the speaker.
   • Check the Arduino sketch for correct UART communication settings (baud rate: 9600 bps).

2. Distorted or Low-Quality Audio:

   • Use an 8-ohm speaker as recommended.
   • Avoid overdriving the SpeakJet IC by sending commands too quickly.

3. SpeakJet Not Responding:

   • Confirm that the shield is securely attached to the Arduino.
   • Check the RX and TX pin connections and ensure they match the Arduino sketch.
   • Reset the SpeakJet IC by sending the 0xC1 reset command.

4. Arduino Upload Fails:

   • Disconnect the shield temporarily while uploading the sketch to the Arduino.
   • Ensure no other devices are using the Arduino's RX/TX pins during upload.

Q: Can I use the VoiceBox Shield with an Arduino Mega?
A: Yes, but you may need to modify the sketch to use the Mega's additional UART ports instead of SoftwareSerial.

Q: Can I play pre-recorded audio files with this shield?
A: No, the SpeakJet IC generates speech and sound effects programmatically. It does not support playback of pre-recorded audio files.

Q: How do I adjust the pitch or speed of the speech?
A: The SpeakJet IC allows you to modify pitch, speed, and other parameters using specific commands. Refer to the SpeakJet datasheet for details.

Q: Is the shield compatible with 3.3V Arduino boards?
A: The shield is designed for 5V operation. Using it with 3.3V boards may require level shifting for proper communication.