On Fri, 25 Oct 2013 21:40:13 +0100, Bill Hill rtufty@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.