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安装 pyserial 串口库

可以直接使用 pip 安装：

sudo pip install pyserial --break-system-packages

或者前往 PyPI 下载 pyserial 的 whl 包进行离线安装：

1. 进入 https://pypi.org/project/pyserial/#files 后下载 Built Distribution 中的 whl 包，这里我使用了最新 3.5 版本
2. 使用 pip 安装：

   sudo pip install pyserial-3.5-py2.py3-none-any.whl --break-system-packages
   

编程

对于本程序的核心思想解析，参考《萤火工场CEM5861G-M11 使用RA6E2点灯》

import sys
import serial
import time

uart_port = "/dev/ttyS0"
baud_rate = 115200

# 状态机的各个状态
STATE_WAIT_HEADER_1 = 0
STATE_WAIT_HEADER_2 = 1
STATE_READ_PAYLOAD = 2

# 定义帧头和帧数据长度
FRAME_HEADER_1 = 0x55
FRAME_HEADER_2 = 0xA5
PAYLOAD_LENGTH = 10  # Data[0]~Data[9]的长度

def calculate_checksum(data):
    """计算校验和"""
    checksum = 0
    for byte in data:
        checksum = (checksum + byte) & 0xFF
    return checksum

def parse_radar_data(data_bytes):
    """解析雷达 Data[0]~Data[9] 部分的数据"""
    if len(data_bytes) < 10:
        print(f"警告: 接收到的数据部分长度不足10字节: {len(data_bytes)}")
        return None

    target_id = data_bytes[0]
    target_status = data_bytes[1]
    distance_cm = (data_bytes[2] << 8) | data_bytes[3]

    speed_raw = (data_bytes[4] << 8) | data_bytes[5]
    speed_ms = speed_raw if speed_raw < 0x8000 else speed_raw - 0x10000

    azimuth_angle = data_bytes[6] if data_bytes[6] < 0x80 else data_bytes[6] - 0x100
    elevation_angle = data_bytes[7] if data_bytes[7] < 0x80 else data_bytes[7] - 0x100
    signal_strength = (data_bytes[8] << 8) | data_bytes[9]

    return {
        "目标ID": target_id,
        "目标状态": target_status,
        "距离(cm)": distance_cm,
        "速度(m/s)": speed_ms,
        "方位角(度)": azimuth_angle,
        "俯仰角(度)": elevation_angle,
        "信号强度": signal_strength
    }

def showUartInfo(uart):
    """
    使用状态机对齐帧并读取雷达数据
    帧格式: 55 A5 [数据长度-高][数据长度-低] [功能码] [命令码1] [命令码2] Data[0]...Data[9] [校验和]
    其中 [数据长度-高][数据长度-低] = 00 0E (从功能码到校验和共 14 字节)，整个帧长度是 18 字节
    """
    global STATE_WAIT_HEADER_1
    global STATE_WAIT_HEADER_2
    global STATE_READ_PAYLOAD

    current_state = STATE_WAIT_HEADER_1
    received_frame = []
    expected_payload_length = 0

    while True:
        byte = uart.read(1)
        if not byte:
            break

        byte_val = ord(byte)

        if current_state == STATE_WAIT_HEADER_1:
            if byte_val == FRAME_HEADER_1:
                received_frame = [byte_val]
                current_state = STATE_WAIT_HEADER_2

        elif current_state == STATE_WAIT_HEADER_2:
            if byte_val == FRAME_HEADER_2:
                received_frame.append(byte_val)
                current_state = STATE_READ_PAYLOAD
                expected_payload_length = 0
            else:
                current_state = STATE_WAIT_HEADER_1
                received_frame = []

        elif current_state == STATE_READ_PAYLOAD:
            received_frame.append(byte_val)

            if len(received_frame) == 4:
                expected_payload_length = (received_frame[2] << 8) | received_frame[3]
                if expected_payload_length != 14:
                    print(f"警告: 接收到非预期的payload长度: {expected_payload_length}. 重新寻找帧头. 帧: {' '.join(f'{b:02X}' for b in received_frame)}")
                    current_state = STATE_WAIT_HEADER_1
                    received_frame = []
                    continue

            if len(received_frame) == 2 + 2 + expected_payload_length and expected_payload_length != 0:
                function_code = received_frame[4]
                command_code_1 = received_frame[5]
                command_code_2 = received_frame[6]

                if function_code == 0x03 and command_code_1 == 0x81 and command_code_2 == 0x00:
                    data_payload = received_frame[7 : 7 + PAYLOAD_LENGTH]
                    received_checksum = received_frame[-1]

                    calculated_checksum = calculate_checksum(received_frame[:-1])
                    if calculated_checksum == received_checksum:
                        print("----------------------------------------")
                        print(f"{' '.join(f'{b:02X}' for b in received_frame)}")
                        radar_status = parse_radar_data(data_payload)
                        if radar_status:
                            print("雷达状态:")
                            for key, value in radar_status.items():
                                print(f"    {key}: {value}")
                        print("----------------------------------------")
                    else:
                        print(
                            f"校验和错误: 计算值 0x{calculated_checksum:02X}, 接收值 0x{received_checksum:02X}. 帧: {' '.join(f'{b:02X}' for b in received_frame)}")
                else:
                    print(
                        f"命令码不匹配: 功能码 0x{function_code:02X}, 命令码1 0x{command_code_1:02X}, 命令码2 0x{command_code_2:02X}. 帧: {' '.join(f'{b:02X}' for b in received_frame)}")

                current_state = STATE_WAIT_HEADER_1
                received_frame = []
                expected_payload_length = 0

            elif expected_payload_length != 0 and len(received_frame) > 2 + 2 + expected_payload_length:
                print(
                    f"警告: 帧长度超出预期，可能失去同步。重新寻找帧头. 帧: {' '.join(f'{b:02X}' for b in received_frame)}")
                current_state = STATE_WAIT_HEADER_1
                received_frame = []
                expected_payload_length = 0

def main():
    try:
        uart = serial.Serial(uart_port, baudrate=baud_rate, timeout=0.1)
        print(f"成功打开串口: {uart_port}@{baud_rate} bps")
        print("等待雷达数据...")

        while True:
            showUartInfo(uart)

    except serial.SerialException as e:
        print(f"串口错误: {e}")
        print(f"请检查串口 {uart_port} 是否存在、未被占用，并且波特率 {baud_rate} 是否正确")
        return 1
    except KeyboardInterrupt:
        print("\n程序终止")
    finally:
        if 'uart' in locals() and uart.is_open:
            uart.close()
            print("串口已关闭")

if __name__ == "__main__":
    sys.exit(main())

接线

运行

在运行程序前需要暂停服务 serial-getty@ttyS0.service：

sudo systemctl stop serial-getty@ttyS0.service

然后运行程序即可看到不停显示的雷达状态：

----------------------------------------
55 A5 00 0E 03 81 00 00 02 00 52 00 00 00 00 05 91 76
雷达状态:
    目标ID: 0
    目标状态: 2
    距离(cm): 82
    速度(m/s): 0
    方位角(度): 0
    俯仰角(度): 0
    信号强度: 1425
----------------------------------------

现象