Receiving UDP broadcast on mbed LPC1768/Mbed OS5

Page last updated 01 Feb 2018, by Yuki Kikuchi. 0 replies broadcast, LPC1768, Receiver, UDP

  • Hardware - mbed LPC1768
  • OS - Mbed OS 5
  • Separate node broadcasting UDP packet to MY_PORT

Information: - LPC176X target code sets flags for broadcast in default. So we can receive broadcast packets without setting additional flag(for LPC1768 register RxFilterCtrl, bit AcceptBroadcastEn)

mbed-os/targets/TARGET_NXP/TARGET_LPC176X/ethenet_api.c ethenet_init()

int ethernet_init() {
...
  LPC_EMAC->RxFilterCtrl = RFC_UCAST_EN | RFC_MCAST_EN | RFC_BCAST_EN | RFC_PERFECT_EN;
                                                      /* Receive Broadcast, Perfect Match Packets */
...
}

code example here:

Import programreceive_udp_broadcast_os5

this code demonstrate how to receive broadcast packet with mbed-os (Mbed OS 5). (tested on LPC1768)

Last commit 01 Feb 2018 by Yuki Kikuchi

you may need this python snippet on your pc to broadcast test message

import sys
import time
import socket

import netifaces as net

BROADCAST_INTERVAL_SEC = 5

HOST = ''
PORT = 58083
interfaces = []
for name in net.interfaces():
        data = net.ifaddresses(name)
        d = data.get(net.AF_INET)
        if d is not None:
                interfaces.append(d[0])

address = None
broadcast_addresses = []
for each in interfaces:
        if 'broadcast' in each.keys():
                broadcast_addresses.append(each['broadcast'])
                address = each['addr']

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
sock.bind((HOST, PORT))

for each in broadcast_addresses:
        msg =  "broadcast from " + address
        sock.sendto(bytes(msg.encode()), (each, PORT))

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