BeagleBone Black: Qt 5.3 fails to send datagrams in UDP

Morix Dev

I cross-compiled Qt 5.3 for BeagleBone Black (running Debian Linux) and I am trying to send some datagrams to broadcast via UDP.

Here is my code:

@ #include <QCoreApplication>
#include <QUdpSocket>
#include <QDebug>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QUdpSocket socket;

    QByteArray d = QString("Hello, world!").toLatin1();
    int r = socket.writeDatagram(d, QHostAddress::Broadcast, 1111);

    qDebug() << r;
    qDebug() << socket.error();
    qDebug() << socket.errorString();

    return a.exec&#40;&#41;;
}@

Unluckily it does not work and the output of the program is:

@-1
QAbstractSocket::NetworkError
"Unable to send a message"@

So the writeDatagram primitive fails. The same exact code works perfectly fine when compiled for my desktop PC... So I am assuming that the code is good and probably there is something specifically related to BBB.

I also tried to send the datagram to a specific IP address (instead of broadcast) but it does not change: BBB seems to be not able to send UDP packets at all...

Any ideas about that? Is there something to be configured on BBB for letting this work?

stukdev

Have you check the ip of the bbb?

Morix Dev

Here is my BBB network setup:

debian@arm:/home/root$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP ql
en 1000
link/ether 1c:ba:8c:da:47:78 brd ff:ff:ff:ff:ff:ff
inet 192.168.79.13/24 brd 255.255.255.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::1eba:8cff:feda:4778/64 scope link
valid_lft forever preferred_lft forever
3: usb0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOW
N qlen 1000
link/ether 56:08:c7:ca:c0:44 brd ff:ff:ff:ff:ff:ff
inet 192.168.7.2/30 brd 192.168.7.3 scope global usb0
valid_lft forever preferred_lft forever

It seems good to me... Am I wrong?

Morix Dev

It seems that on Linux you have to bind on a given interface for broadcasting packets out ot if...

You can read the full story "here":http://stackoverflow.com/questions/24866807/beaglebone-black-qt-5-3-fails-to-send-datagrams-in-udp?noredirect=1#comment38645537_24866807