忘记说了MircoPython中socket.inet_aton()方法也没有，但是自己实现了一个，方法代码如下：

def inet_aton(ipv4):
    ips = ipv4.split('.')
    return int(ips[0]) * 2 ** 24 + int(ips[1]) * 2 ** 16 + int(ips[2]) * 2 ** 8 + int(ips[3])

想使用组播的方式实现设备自动发现，在Python上经测试没有问题，可以正常接收，代码如下：

import socket
import struct
import sys

multicast_group = '224.0.0.6'
server_address = ('', 23333)

# Create the socket
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

# Bind to the server address
sock.bind(server_address)
# Tell the operating system to add the socket to the multicast group
# on all interfaces.
group = socket.inet_aton(multicast_group)
mreq = struct.pack('4sL', group, socket.INADDR_ANY)
sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)
# Receive/respond loop
while True:
    print >>sys.stderr, '\nwaiting to receive message'
    data, address = sock.recvfrom(1024)

    print >>sys.stderr, 'received %s bytes from %s' % (len(data), address)
    print >>sys.stderr, data

    print >>sys.stderr, 'sending acknowledgement to', address
    sock.sendto('ack', address)

将代码改为MircoPython后，发现以下属性未定义

socket.INADDR_ANY
socket.IPPROTO_IP
socket.IP_ADD_MEMBERSHIP

就自己找到了Python中定义的对应值填入MircoPython中，代码如下：

sock = usocket.socket(usocket.AF_INET, usocket.SOCK_DGRAM)
sock.bind(usocket.getaddrinfo('0.0.0.0', 23333)[0][-1])
group = inet_aton('224.0.0.6')
mreq = ustruct.pack('4sL', group, 0)
sock.setsockopt(0, 12, mreq)
while True:
    print('waiting to receive message')
    data, address = sock.recvfrom(1024)
    print('received %s bytes from %s' % (len(data), address))

然后在OpenMV中运行就报如下错误：

Traceback (most recent call last):
  File "<stdin>", line 39, in <module>
TypeError: object with buffer protocol required

请问这个是什么情况？是因为MircoPython不支持Multicast吗？

代码如下

import sys

print(sys.version)
print(cmp(1, 1))

错误信息

Traceback (most recent call last):
  File "<stdin>", line 5, in <module>
NameError: name 'cmp' is not defined
MicroPython v1.9.2-4442-g8d787e97 on 2018-01-24; OPENMV3 with STM32F765
Type "help()" for more information.
>>>