select on udp recvfrom doesn't work ???
Lennart Sorensen
lsorense-1wCw9BSqJbv44Nm34jS7GywD8/FfD2ys at public.gmane.org
Wed Aug 11 16:29:14 UTC 2010
On Wed, Aug 11, 2010 at 12:23:40PM -0400, Lennart Sorensen wrote:
> On Wed, Aug 11, 2010 at 12:14:55PM -0400, Lennart Sorensen wrote:
> > > So this was a bust. The rtc on this board a ts7260 cannot generate interrupts :(
> > >
> > > The chip itself has an rtc and some internal timers that could
> > > generate interrupts.
> > >
> > > The question still remains how to get them synchronized to the same
> > > place in time. Using a udp message which would arrive roughly at the
> > > same time to all devices still seems plausible ?
> >
> > How about this little example. It waits for a UDP message (anything at
> > all) on port 5000, and when that happens it starts to print a message
> > every 10 ticks, with a tick rate of 10ms, (so 10 times per second it
> > does the print).
> >
> > I start it by doing:
> >
> > echo "Foo" | nc -u ipaddress 5000 -q 1
> >
> > nc is netcat. Any other udp capable network connection should work too.
>
> By the way you can do a broadcast using something like:
>
> echo "Foo" | nc -b -u broadcastaddress 5000 -q 0
>
> So if your network is 192.168.1.0/24 then do:
>
> echo "Foo" | nc -b -u 192.168.1.255s 5000 -q 0
Oops. Typo.
echo "Foo" | nc -b -u 192.168.1.255 5000 -q 0
--
Len Sorensen
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