SparkFun Forums

[nicola]

Hello, i have two computers connected by xbee. I've properly configured them and the serial ports are working, they can communicate.
Anyway, i'd like to have a TCP/IP connection over the serial one, so that i can use standard network software. Is there a simple way? From what i've read around, i have to set up either a PPP or SLIP connection over the serial one, but guides around usually talk about modem and dialing numbers etc. I can't figure out how this work.
One of the two machines is WinXP, the other is Ubuntu Linux.

[stevech]

On the far end, what device is connected to an XBee? Often the XBee is used alone, with its built-in A/D and digital I/O "virtual wire" firmware. Also common is a low cost microprocessor attached to the serial port of the XBee, and your firmware app on the microprocessor does whatever, and uses its simple serial port to talk wirelessly with an app somewhere, say, on a PC.

Running IP on 802.15.4 is done via the 6LoWPAN firmware that's public domain and supported by certain vendors - sort of. It's unpopular. Of course, with 100 byte packets, all kinds of IP header compression schemes are needed. So using 802.15.4 as the transport for IP packets is out of sorts and a needless complexity because these peer to peer 802.15.4 networks, or rarely '15.4 with ZigBee mesh routing is equivalent to TCP and IP. There are proprietary mesh routing network layers, e.g., Digi's DigiMesh or whatever it's now called.

But really, few uses of short range star topology 802.5.4 networks need IP and certainly not TCP.

Suggest you begin by using XBee's standard wireless serial port extension. This connects COMn on PC #1 to COMn on PC #2, transparently, though you must deal with flow control via hardware CTS or some software messaging convention - to prevent overrunning the capacity of the '15.4 channel.

SLIP could be done using the wireless serial port extension firmware in the XBee. Will be rather slow due to the huge overhead versus the 100 byte packets in 802.15.4.

[pbender]

From what i've read around, i have to set up either a PPP or SLIP connection over the serial one, but guides around usually talk about modem and dialing numbers etc. I can't figure out how this work.

Yes, the traditional way of doing this is with SLIP or PPP. You need to look for information about using these protocols over a null modem.

This will work, but it will also be slow.

If you just need to log in to the linux box remotely, I would look for information on setting up getty to handle a terminal connection over the serial port instead. This is a simpler configuration, and it is something you should make sure is working before moving on to SLIP or PPP.

Paul

[stevech]

Check this SLIP for AVRs, Arduino and the uIP TCP/IP stack

http://www.arduino.cc/playground/Code/SerialIP

With the Series 1 XBee, my experience has been that you can get about 80Kbps of net throughput. SLIP is often used on much slower modems and whatnot.

But truly, a Wiznet 812MJ is a far simpler way to go.

[stevech]

can you put a PCMCIA WiFi card in that laptop?

[stevech]

Well, consider using its serial RS232 port with
http://www.lantronix.com/device-network ... -plus.html
or much better
http://www.connectone.com/EmbeddedDeviceServers.asp

I've used both


WEP128 is fine, in my opinion, unless you live in a University dorm.

[Valen]

My messages got removed because somehow my forum account got accidentally removed by a moderator dealing with spam-messages. If you were wondering.

Anyway, I managed to get a PCMCIA netword card hooked up to the old laptop. I'm trying to get Win95 and Win7 to talk to eachother so I don't need to swap the harddisk in an out every time to transfer files. And also bought a second-hand bluetooth pcmcia card for it. I forgot about that wireless option. I guess I will have to live with that protocol not being very secure. But I still want to try that SLIP or PPP thing one day.