RDK: Serial Port Communication

Introduction

This repository provides Python example code for communication between the RDK X5 (Raspberry Pi) platform and the AI voice interaction module, supporting two communication methods: I2C and UART.

• Speech recognition module: supports offline speech recognition and outputs the command ID after recognition

• Playback functions: supports passive playback, function word playback and command word playback

• Communication protocol: I2C address 0x2A, UART baud rate 115200

• Programming language: Python 3

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Hardware Connection

General Connection

Important: make sure all devices share a common ground!

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UART Version Connection

Note: the /dev/ttyAMA0 serial device is used by default

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Type-C Data Cable Connection (UART Alternative)

If a USB-TTL adapter module is used:

Note: in this case the serial device is usually /dev/ttyUSB0

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Environment Setup

System Requirements

• RDK X5

• Ubuntu / Debian system

• Python 3.7+

Install Dependency Packages

# Update packages
sudo apt update
sudo apt upgrade -y

# Install Python libraries
sudo apt install -y python3-pip

# Install pyserial
pip3 install pyserial

Enable the Serial Port Interface

# Open the configuration tool
sudo raspi-config

# Select Interface Options → Serial
Select: No (shell) → Yes (hardware serial port)
# Reboot to take effect
sudo reboot

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Using the UART Version

Check the Code Files

cd UART_Voice
ls -la
# You should see uart_voice.py

Configure the Serial Port Device

Edit the uart_voice.py file and modify the serial port device:

# UART direct connection (default)
SERIAL_PORT = '/dev/ttyAMA0'

# Or use a USB-TTL adapter
SERIAL_PORT = '/dev/ttyUSB0'

# Baud rate
BAUD_RATE = 115200

Run the Program

Grant Execute Permission

chmod +x uart_voice.py
# Run (sudo privileges required to access the serial port)
sudo python3 uart_voice.py

Running Test

After a normal startup it will display:

Speech Serial Opened! Baudrate=115200

Say a command word to the voice module and the corresponding ID will be displayed:

Speech Serial Opened! Baudrate=115200
ID:1
ID:4
ID:10

Stop the Program

Press Ctrl + C to stop the program

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Troubleshooting

Q1: The serial device cannot be found

A: Check:

1. Check whether the serial port is enabled (raspi-config)

2. Check whether the device name is correct

   • UART direct connection: /dev/ttyAMA0

   • USB-TTL: /dev/ttyUSB0 or /dev/ttyUSB1

3. Check whether the hardware connection is correct

4. Check whether the serial port is occupied by another program

# View available serial ports
ls /dev/tty* | grep tty

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Q2: The command ID only shows 0 or does not appear

A: Normal behavior:

• 0 = no valid command recognized

• the ID is output only when a valid command word is spoken

• wake the module first, then say the command

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Q3: Recognition accuracy is not high

A: Optimization suggestions:

• Keep the environment quiet and the background noise low

• Keep a moderate distance from the microphone (10-50cm)

• Speak at a moderate rate and articulate clearly

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Q4: Abnormal serial port communication

A: Check:

1. Whether TX/RX are cross-connected (module TX → RPi RX)

2. Whether the baud rate is 115200

3. Whether the grounds are common

4. Whether the serial port is occupied by another process

# Check serial port usage
sudo lsof /dev/ttyAMA0

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Technical Support

If there are problems, please check:

1. Whether the hardware wiring is correct (a common ground is very important!)

2. Whether the serial port baud rate is 115200

3. Whether there is sufficient permission to access the hardware interface

Common Debugging Commands

ls -l /dev/ttyAMA0   # View the serial port device
groups                # Check user group permissions

Related Products

AI Voice Interaction Module→