pymavlink使用

一、建立连接

from pymavlink import mavutil

# Start a connection listening on a UDP port
the_connection = mavutil.mavlink_connection('udp:localhost:14540')

# Wait for the first heartbeat 
#   This sets the system and component ID of remote system for the link
the_connection.wait_heartbeat()
print("Heartbeat from system (system %u component %u)" % (the_connection.target_system, the_connection.target_component))

# Once connected, use 'the_connection' to get and send messages 

 

连接字符串

[protocol:]address[:port]

• protocol (optional): The IP protocol. If not specified pymavlink will attempt to determine if the address is a serial port (e.g. USB) or a file, and if not will default to a UDP address.
  • tcp: Initiate a TCP connection on the specified address and port.
  • tcpin: Listen for a TCP connection on the specified address and port.
  • udpin: Listen for a UDP connection on the specified address and port.
  • udpout: Initiate a TCP connection on the specified address and port.
  • udp: By default, same as udpin. Set mavlink_connection parameter input=False to make same as udpout.
  • udpcast: Broadcast UDP address and port. This is the same as udp with mavlink_connection() parameters input=False and broadcast=True.
• address: IP address, serial port name, or file name
• port: IP port (only if address is an IP address)

Some of the strings you can use for different types of connections are listed below.

Connection type	Connection string
Linux computer connected to the vehicle via USB	/dev/ttyUSB0
Linux computer connected to the vehicle via Serial port (RaspberryPi example)	/dev/ttyAMA0 (also set baud=57600)
MAVLink API listening for SITL connection via UDP	udpin:localhost:14540 (or udp:localhost:14540, 127.0.0.1:14540,etc.)
MAVLink API initiating a connection to SITL via UDP	udpout:localhost:14540 (or udpout:127.0.0.1:14540)
GCS connected to the vehicle via UDP	127.0.0.1:14550 or udp:localhost:14550
SITL connected to the vehicle via TCP	tcp:127.0.0.1:5760 (ArduPilot only, PX4 does not support TCP)
OSX computer connected to the vehicle via USB	dev/cu.usbmodem1
Windows computer connected to the vehicle via USB (in this case on COM14)	com14
Windows computer connected to the vehicle using a 3DR Telemetry Radio on COM14	com14 (also set baud=57600)

 

二、发送消息

方式1、使用封装函数

封装函数位置: ../pymavlink/mavutil.py  =>  mavlink_connection

from pymavlink import mavutil

the_connection = mavutil.mavlink_connection('udp:localhost:14540')
the_connection.wait_heartbeat()
# 获取航线列表
the_connection.waypoint_request_list_send()

注意：该方式单个mavlink连接不支持多架无人机共用通信

 

方式2、使用<message_name>_send()直接发送

<message_name>_send()函数位置: ../pymavlink/dialects/v20/ardupilotmega.py  => MAVLink

　　　　　　　　　　　　　　　　../pymavlink/dialects/v10/ardupilotmega.py  => MAVLink

from pymavlink import mavutil

the_connection = mavutil.mavlink_connection('udp:localhost:14540')
the_connection.wait_heartbeat()
# 获取航线列表
target_system = the_connection.target_system
target_component = the_connection.target_compontent
the_connection.mav.mission_request_list_send(target_system, target_component)

注意：单个mavlink连接复用多架无人机通信时，可以使用该方式

 

方式3、使用send()发送<message_name>_encode()生成的mavlink消息

<message_name>_encode()函数位置: ../pymavlink/dialects/v20/ardupilotmega.py  => MAVLink

　　　　　　　　　　　　　　　　　../pymavlink/dialects/v10/ardupilotmega.py  => MAVLink

from pymavlink import mavutil

the_connection = mavutil.mavlink_connection('udp:localhost:14540')
the_connection.wait_heartbeat()
# 获取航线列表
target_system = the_connection.target_system
target_component = the_connection.target_compontent
# 生成mavlink消息
# pymavlink.dialects.v20.ardupilotmega.MAVLink_param_request_list_message
mission_request_list_message = the_connection.mav.mission_request_list_encode(target_system, target_component)
# 发送mavlink消息
the_connection.mav.send(mission_request_list_message)

 

 方式4、使用write()发送mavlink消息bytes

from pymavlink import mavutil

the_connection = mavutil.mavlink_connection('udp:localhost:14540')
the_connection.wait_heartbeat()
# 获取航线列表
target_system = the_connection.target_system
target_component = the_connection.target_compontent
# 生成mavlink消息
# pymavlink.dialects.v20.ardupilotmega.MAVLink_param_request_list_message
mission_request_list_message = the_connection.mav.mission_request_list_encode(target_system, target_component)
# mavlink消息打包成字节码
mission_request_list_message_bytes = mission_request_list_message.pack(the_connection.mav)
# 发送mavlink消息字节码
the_connection.write(mission_request_list_message_bytes)

 

 三、接收消息

1、recv_msg()

from pymavlink import mavutil

the_connection = mavutil.mavlink_connection('udp:localhost:14540')
the_connection.wait_heartbeat()
# mavlink消息
msg = the_connection.recv_msg()

 

2、recv_match()

from pymavlink import mavutil

the_connection = mavutil.mavlink_connection('udp:localhost:14540')
the_connection.wait_heartbeat()
# mavlink消息
msg = the_connection.recv_match(type='SYS_STATUS', condition='SYS_STATUS.mode==2 and SYS_STATUS.nav_mode==4', block=True)

 

四、发送一个心跳

# Send heartbeat from a GCS (types are define as enum in the dialect file). 
the_connection.mav.heartbeat_send(mavutil.mavlink.MAV_TYPE_GCS,
                                                mavutil.mavlink.MAV_AUTOPILOT_INVALID, 0, 0, 0)

# Send heartbeat from a MAVLink application. 
the_connection.mav.heartbeat_send(mavutil.mavlink.MAV_TYPE_ONBOARD_CONTROLLER,
                                                mavutil.mavlink.MAV_AUTOPILOT_INVALID, 0, 0, 0)

 

五、消息签名

# Assuming you already have a connection set up
the_connection = mavutil.mavlink_connection(...)

# Create a callback to specify the messages to accept
def my_allow_unsigned_callback(self,msgId):
    #Allow radio status messages
    if msgId==mavutil.mavlink.MAVLINK_MSG_ID_RADIO_STATUS:
        return True
    return False

# Pass the callback  to the connection (here we also pass an arbitrary secret key)
secret_key = chr(42)*32
the_connection.setup_signing(secret_key, sign_outgoing=True, allow_unsigned_callback=my_allow_unsigned_callback)

 

六、生成mavlink消息bytes

from pymavlink import mavutil

the_connection = mavutil.mavlink_connection('udp:localhost:14540')
the_connection.wait_heartbeat()
# 获取航线列表
target_system = the_connection.target_system
target_component = the_connection.target_compontent
# 生成mavlink消息
# pymavlink.dialects.v20.ardupilotmega.MAVLink_param_request_list_message
mission_request_list_message = the_connection.mav.mission_request_list_encode(target_system, target_component)
# mavlink消息打包成字节码
mission_request_list_message_bytes = mission_request_list_message.pack(the_connection.mav)

 

七、mavlink消息bytes转mavlink消息

from pymavlink import mavutil
from pymavlink.dialects.v20.ardupilotmega import MAVLink

the_connection = mavutil.mavlink_connection('udp:localhost:14540')
the_connection.wait_heartbeat()
# 获取航线列表
target_system = the_connection.target_system
target_component = the_connection.target_compontent
# 生成mavlink消息
# pymavlink.dialects.v20.ardupilotmega.MAVLink_param_request_list_message
mission_request_list_message = the_connection.mav.mission_request_list_encode(target_system, target_component)
# mavlink消息打包成字节码
mission_request_list_message_bytes = mission_request_list_message.pack(the_connection.mav)
# mavlink消息bytes转mavlink消息
# 创建MAVLink对象用来解析bytes数据
mavlink_obj = MAVLink('parse_message')
# 解析mavlink消息bytes
mavlink_message = mavlink_obj.parse_buffer(mission_request_list_message_bytes)[0]
msg_dict = mavlink_message.to_dict()

 

参考：https://mavlink.io/en/mavgen_python/#setting_up_connection