Jetson Nano Serial Communication

Note: The voice interaction module needs to be flashed with the factory firmware. If the voice chip has not been flashed with firmware after being received, it does not need to be flashed.

1. Check the port

Connect to the Jetson Nano motherboard via the USB interface.

When inputting at the terminal, the appearance of the ttyUSB0 device indicates normal recognition (usually it is ttyUSB0, but it could also be other device numbers)

ls /dev/ttyUSB*

2. Code Implementation

Download speech_serial.py to the corresponding directory

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import time
import serial
from typing import Optional, Tuple


class SpeechModule:
    """
    语音模块串口通信控制器
    封装了与语音模块的交互逻辑
    """
    
    # 串口配置常量
    DEFAULT_PORT = "/dev/ttyUSB0"
    DEFAULT_BAUDRATE = 115200
    
    # 命令字定义 (播报词/功能ID)
    CMD_THIS_RED = 0x60
    CMD_THIS_GREEN = 0x61
    CMD_THIS_YELLOW = 0x62
    CMD_RECOGNIZE_YELLOW = 0x63
    CMD_RECOGNIZE_GREEN = 0x64
    CMD_RECOGNIZE_BLUE = 0x65
    CMD_RECOGNIZE_RED = 0x66
    CMD_INIT = 0x67

    def __init__(self, port: str = DEFAULT_PORT, baudrate: int = DEFAULT_BAUDRATE):
        self._port = port
        self._baudrate = baudrate
        self._serial_conn: Optional[serial.Serial] = None

    def connect(self) -> bool:
        """建立串口连接"""
        try:
            self._serial_conn = serial.Serial(self._port, self._baudrate, timeout=0.1)
            if self._serial_conn.is_open:
                print(f"[Connected] Speech Serial Opened! Baudrate={self._baudrate}")
                return True
            return False
        except serial.SerialException as e:
            print(f"[Error] Speech Serial Open Failed: {e}")
            return False

    def send_command(self, cmd_id: int) -> None:
        """
        发送指令帧
        协议格式: 0xAA 0x55 0xFF [Data] 0xFB
        """
        if not self._serial_conn or not self._serial_conn.is_open:
            return

        # 构造完整的数据帧
        frame = bytes([0xAA, 0x55, 0xFF, int(cmd_id), 0xFB])
        
        self._serial_conn.write(frame)
        time.sleep(0.005)
        self._serial_conn.reset_input_buffer()  # 等同于 flushInput

    def read_response(self) -> Optional[int]:
        """
        读取并解析返回数据
        返回: Read_ID (第6个字节的数据)
        """
        if not self._serial_conn or not self._serial_conn.is_open:
            return None

        # 检查缓冲区数据量
        bytes_available = self._serial_conn.in_waiting
        if bytes_available <= 0:
            return None

        raw_data = self._serial_conn.read(bytes_available)
        hex_str = raw_data.hex()

        # 校验帧头 'aa55'
        if hex_str.startswith('aa55'):
            try:
                # 简单的索引提取逻辑 (与原代码逻辑保持一致)
                # 注意：此处假设数据长度足够，实际工业代码建议加长度校验
                # byte1 = hex_str[4:6] # 保留原逻辑中的第5字节但不使用
                byte2 = hex_str[6:8] # 提取第6字节
                
                read_id = int(byte2, 16)
                
                self._serial_conn.reset_input_buffer()
                time.sleep(0.005)
                print(f"Read_ID: {read_id}")
                return read_id
            except (IndexError, ValueError):
                pass
        
        return None

    def run(self):
        """主运行循环"""
        if not self.connect():
            return

        # 初始化模块
        self.send_command(self.CMD_INIT)
        time.sleep(0.005)

        print("[Listening] Waiting for data...")
        try:
            while True:
                self.read_response()
        except KeyboardInterrupt:
            print("\n[Stopped] Program interrupted by user.")
        finally:
            if self._serial_conn and self._serial_conn.is_open:
                self._serial_conn.close()
                print("[Disconnected] Serial port closed.")


if __name__ == "__main__":
    module = SpeechModule()
    module.run()

3. Implementation Effect

The content of the broadcast can be viewed according to the protocol in the <Command Word and Broadcast Word Protocol List V1_Chinese File> provided in the attachment.

Among them, the first and second bytes AA 55 represent the frame header of the protocol, the third byte 00 represents the broadcast function, the fourth is the ID of the broadcast content, where we can see that "the car moves forward" is 0x07 in hexadecimal, so sending 0x07 to register 0x03 in the program will broadcast the corresponding content. The fifth byte is the end frame.

Enter the following command in the terminal to run the program

python3 -m speech_serial

After saying the wake word Wake , the Console will reply with the received Read_ID: 0

says "Turn off the light", and the Console will reply with Receiving Read_ID: 13

At this time, you can open the attached "Command Word and Announcement Word Protocol List V1_Chinese File" to view the protocol for "Turn off the light"

Among them, the first and second ByteDances AA 55 represent the frame header of the protocol, the third ByteDance represents the ID of the ten functional words of the chip, the fourth is the ID of the command word, where we can see that "turn off the light" is 0D in hexadecimal and 13 in decimal. The fifth ByteDance is the end frame.

If you say other command words, the Console will also print the corresponding command word ID. You can try it yourself.