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XBee Pro API — Parallax Forums

XBee Pro API

Jay KickliterJay Kickliter Posts: 446
edited 2009-03-04 03:37 in Propeller 1
I've been working on a project where I need to use non-mesh XBee's in API mode and 64-bit addressing. After a couple days, it is starting to work. I was only going to write in the functionality I need, but if there is anyone with interest in this let me know what you need/want.

Comments

  • Mike HuseltonMike Huselton Posts: 746
    edited 2009-03-03 09:41
    Finish up what you have. Post what you have and I will critique it. Any added functions that come to mind are room for discussion.

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    JMH
  • JonathanJonathan Posts: 1,023
    edited 2009-03-03 15:59
    Jay,

    I have a project where I will have 4 xbee's in a chain. I will need to have them pass data so that I can send a query or command to the xbee at the end of the chain. So, I need to figure out how to pass data from one unit to the other. Any help in this would be much appreciated.

    Jonathan

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    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
  • Jay KickliterJay Kickliter Posts: 446
    edited 2009-03-03 16:58
    Jonathan, you need is XBees with MESH. They are designed to do this automatically. I think you just send the message to address of the module(s) you're trying to reach, and the XBee's coordinate to get it there. I can't design for that, since I purposely am not using MESH XBee's (they have lower bandwidth due to all that traffic).
  • JonathanJonathan Posts: 1,023
    edited 2009-03-03 17:49
    Jay,

    So, is MESH a firmware or hardware thing? I have xbee pro 60mW units. I took a quick look in the docs (I'm at work) but didn't see anything about mesh.

    Thanks!

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    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
  • Jay KickliterJay Kickliter Posts: 446
    edited 2009-03-03 20:07
    You'll have to ask Digi, I'm pretty sure it is firmware. I think I remember seeing something about the ability to re-flash them.
  • ianwianw Posts: 32
    edited 2009-03-03 21:26
    Hi Jay - hope I'm not hijacking your thread with all this additional information about XBee, but since you, Oliver, and I discussed XBee module selection I thought I'd update with a few numbers I gathered, since much of it is not available at the Digi site. If you prefer, I'd be happy to move it to a different thread too.

    @Jonathan: If you have a 60 mW output I'll assume you're reffering to the 802.15.4 modules (actually 63 mW):
    www.digi.com/products/wireless/point-multipoint/xbee-series1-modulespecs.jsp
    If you have all Maxstream devices, you can flash these devices with the Maxtstream proprietary DigiMesh protocol to get mesh networking (it is not ZigBee compatible, but faster).

    They also sell a Zigbee ZB product, formerly known as Zigbee 2.5 but now with a firmware upgrade and brand new marketing, it IS different hardware than the module above so not firmware compatible, it is found here:
    www.digi.com/products/wireless/zigbee-mesh/xbee-zb-modulespecs.jsp
    but I would stay away from this unless you have ZigBee specific devices from other manufacturers that you're trying to talk to - for why, see below

    Since I haven't seen it posted anywhere else I'll provide some hard numbers I've gathered regarding range and actual realized throughput for the different modules. *the numbers assume a standard dipole antenna and a relatively quiet chunk of spectral space*

    2.4 GHz

    Zigbee module realized throughput: 25 kbps - ouch that's slow, there's lot of overhead in this protocol...
    802.15.4 module realized throughput: 115 kbps
    I'm not sure what the numbers are for DigiMesh since I don't need mesh in my application, but I understand it is at least 3x their Zigbee module.

    range with los: 1 mile - if you add a 6 db gain into either the Tx/Rx of the system you can double this range
    range with non los: 300 ft - if you add a 12 db gain into either the Tx/Rx of the system you can double this range

    Although WiFi and 802.14.5 have collision avoidance and can coexist, it is good to minimize problems and optimize channel selection. I have a spectral analysis of a WiFi network operating across different channels with the Maxstream modules to image the overlap. Wi-Fi (802.11x)has 3 non overlapping channels in the US - 1, 6, and 11. So, these are the most commonly selected channels for Wi-Fi with channel 6 often the default. Assuming this, you can select channels 0x0F or 0x14 for the Maxstream to minimize probability of Wi-Fi interference. But ISM 2.4 is crowded with phones, microwaves and all sorts of stuff, so 900 is likely better for you. In general, when working with the Maxstream devices, I would stay away from 2.4GHz for most applications, since their 900 MHz modules will have better throughput and range than their 2.4 counterparts.

    900 MHz
    www.digi.com/products/wireless/point-multipoint/xbee-pro-900.jsp
    module realized throughput: 156 kbps
    range with los: 3 mile
    range with non los: 450 ft

    The 900 MHz can be loaded with the DigiMesh firmware too if you need it, again you'd have to test what the overhead looks like.
  • Mike HuseltonMike Huselton Posts: 746
    edited 2009-03-04 03:37
    I have been using Xbee products for five years. The are excellent.

    Again, what are you going to include in the API? Just post the damn thing and let us experienced people start critiquing and offering suggestions.
    Are you ashamed to post your code? Don't be - perfection doesn't exist.

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    JMH
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