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[SOLVED] XBee 868 MHz two ways communication

Posted by giu on June 15, 2011 at 3:30pm
One of the things not clearly said in the Wiki is that when you set Xbee communication, you MUST define correctly the addresses of the modules, otherwise you'll not get right communication.
After, 8 hours of chatting, writing post forum and headache, I noticed this fact when I tried a range test of Xbee by using X-CTU tool by Digi. One module was in loopback (just connect the DDI to DDO on the planeboard of the Xbee, and, obviously, connect the 5V), and the other one was connected to the PC by using a Sparkfun USB expansion board.
The RSSI LED was ON only on the Xbee end, but that one on the PC was OFF. Thus the receiver end was receiving packets from the PC, not viceversa.

Then, I configured the addresses in X-CTU, precisely, in the following way:

Xbee A
DH = address SH of B
DL = address SL of B

Xbee B
DH = address SH of A
DL = address SL of A

One more thing: as descrived in the Wiki, let set the Network ID parameter to be the same for both modules.

I have XB08-DP as firmware, which support only one channel and no MY address.
I ran a range test and all was fine like a charm!
Same, when I attached the Xbee on the APM, switched in Flight Mode, opened up a GCS and saw only data come from the copter.

Remember also to try lower serial data rate if the higher ones do not work. In my settings I tried 57600 as baudrate.
Tags: xbee
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Comments

  • Andrey May 15, 2013 at 8:50am

    Hello, really need your help. Connected to the xbee 868 apm2.5, everything works fine, but after a while xbee stops working since 10% of the limit. Tell me please: how to implement an automatic reset every 5 minutes.

  • Wojciech August 30, 2011 at 12:27pm

    Does anybody succed in implementing Marcus Fahlén's reset solution in APM?

    @ Martint ("There was a change in firmware on the units, I think this put pay to the work around at a software level,"):

    - X-CTU let us choose firmware version so this should be not an issue

  • Andrew Miller June 16, 2011 at 8:33am

    I too tried to get these XBees working without much success, I have since bought a bluetooth modem which works just fine for my purposes, a note about the firmware is that Digi still have old firmwares on their FTP site - not sure which one stopped the workaround but there are 4 different firmwares available including the latest one. - hope this helps

     

    Andrew

  • Distributor
    Martint BuildYourOwnDrone.co.uk June 16, 2011 at 12:50am
    I see you also add a link to my findings at the back end of last year:

    http://www.diydrones.com/profiles/blogs/xbee-868-revived

    There was a change in firmware on the units, I think this put pay to the work around at a software level, hardware hack is not great! please do keep us updated on your progress.

    Regards

    Martin
  • giu June 16, 2011 at 12:45am
    Maybe a solution about duty cycle could be that of buffering data inside the APM. Or, rather, send data to Xbee not continuously, but at sampling period. Data for telemetry are not so import to gain the right to be streamed continuously. I will make some computations...
  • giu June 16, 2011 at 12:29am
    @ HappyKillmore: but we can use the workaround by Marc http://www.diydrones.com/profiles/blogs/xbee-868-revived.
    If anyone succeed in implementing inside APM, let us know, please.
    G
  • giu June 16, 2011 at 12:28am
    Thank martin (I see that you are from buildyourdrone! I just bought something one week ago).
    I think that the duty cycle and the low data rate problem of Xbee 868 is quite serious, as others in this site noted one year ago.
    Anyway, I will try.
    I found other long range module in low bands, like this http://www.linxtechnologies.com/resources/data-guides/trm-xxx-lt.pdf. If one day I will be plenty of free time I will do some design...
  • Distributor
    Martint BuildYourOwnDrone.co.uk June 16, 2011 at 12:16am

    Hello Giu,

    I did try to get back to you last night to continue where we had left off, the call I was on took longer than I had anticipated! Great to see you have the communication up and running now!
    I hope you are able to get a work around on the duty cycle :)

    Regards

    Martin

  • Paul Mather June 15, 2011 at 7:47pm

    You should be using 19200 max for your 868's. Anything higher isn't accurate. You'll only be able to run about 2 maybe 3Hz on the MAVlink data. Then you'll find that your X-Bee's will stop communicating after 6 minutes of use unless you use the hack to reboot the thing every couple minutes. The 868's are pretty much fantastic for range but unusable due to laws....

     

    http://www.digi.com/pdf/chart_xbee_rf_features.pdf

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