26 Oct
2013
26 Oct
'13
2:05 p.m.
On Fri, 25 Oct 2013 21:40:13 +0100, Bill Hill <rtufty(a)gmail.com>
wrote:
That may well be it. The ATBD command reads
"7" which is 115200: is that just the Xbee-to-USB communication, though,
rather than the actual radio pathway baud rate?
Yes, the ATBD is the interface baud rate, the radios will have their
own rate depending on the model. The S3B is a 200kbps radio.
A ping -i5 gives an average og 63mS and no packets
lost, but ping -i1
root@raspberry:~# ping -i1 192.168.24.16
PING 192.168.24.16 (192.168.24.16) 56(84) bytes of data.
64 bytes from 192.168.24.16: icmp_req=1 ttl=64 time=65.9 ms
64 bytes from 192.168.24.16: icmp_req=2 ttl=64 time=4038 ms
64 bytes from 192.168.24.16: icmp_req=10 ttl=64 time=21170 ms
64 bytes from 192.168.24.16: icmp_req=16 ttl=64 time=28444 ms
64 bytes from 192.168.24.16: icmp_req=17 ttl=64 time=30579 ms
^C
--- 192.168.24.16 ping statistics ---
35 packets transmitted, 5 received, 85% packet loss, time 72092ms
rtt min/avg/max/mdev = 65.951/16859.755/30579.670/12549.475 ms, pipe 13
That's definitely a problem. This would appear to be either a weak
radio path or interference if not for the fact the longer interval
yields no loss. A bad RTT estimate in the stack for that interface
might be a factor. I suspect the higher ping rate is just forcing the
radio to transmit sooner and it never sees the reply because you've
forced collisions between the radios. IOW, you're creating your own
interference.
No CSMA? No duplex? Which model XBees are you using?
I'm still learning my way around CodeWarrior and the XBIB so I don't
know how much code I can stuff into the kit.
I've got two units sending text to each other in bypass mode in their
out-of-the-box configuration via RealTerm. Initial baud to the XBIB is
115200 but I have to switch the terminal applications to 9600 baud to
get valid data across the link. The radios go to sleep when not
transmitting data and the signal strength indicators on the XBIB's
light up when the link is active. I'm using the third as my hack-toy
on the debugger.
I'm more interested in thoughts about using the Raspberry Pi versus
the Beagleboards as a platform. I might just buy both and run a
comparison but I won't have much time to toy around until November.
--
Geoff Joy - ke6qh -
AmprNet IP Address Coordinator for San Bernardino & Riverside Counties.
geoff(a)windomeister.com