My understanding is also that ZigBee is not quite ready to go industrial ye= t = and it has quite a lot of overhead for just a simple wireless network. But = you = may also take a look at IEEE 802.15.4 radios. This has a lot of the feature= s = provided by ZigBee (since ZigBee is built upon IEEE 802.15.4) and looks lik= e it = could be very usefull for a small wireless sensor network. There are also other stacks than ZigBee built on the PHY and MAC IEEE 802.1= 5.4 = layers (WiMi?) that could be worth checking out. Things to consider when deciding a technology and standard for wireless = devices: Range Power requirement (battery operated or mains power?) Data rate Point to point, point to multi point or multi point to multi point Number of nodes in one network Single or several networks (of same type) in the same area World wide or local Certification Interoperability with other networks on same frequency Security Price Second source /Ruben > mamouda@web.de wrote: > > = > > I'd like to design a wireless sensor network (20 sensors) using PIC > > microcontrollers. > > = > > Which PICs do you think is better for that purpose and which wireless > > technology (Zigbee. WiMi ?) > = > I have used XBees for several devices, but would like to move over to = > PICs with a Microchip stack at some point to reduce per-unit cost. > = > My feeling at this point is that ZigBee has a lot of nice features, but = > if you don't need them, the fact that it's a standard is NOT important, = > because no two ZigBee stacks interoperate yet (as I understand it). So = > it's really no more "standard," at this point, than Microchip's MiWi. > = > So - my decision tree goes like this: > = > A. Is short development time far more important than per-unit cost? Or, = > are you looking to sell the product commercially? Go with XBee. (FCC = > approval is a major cost otherwise.) There are some other similar = > modules that are no worse, but as far as I can tell, not particularly = > better either. > = > B. If per-unit cost is important, and FCC approval isn't (or you can = > afford it), try Microchip's ZigBee solution. Their stack is free, but = > you still have to join the "ZigBee Alliance" ($K). > = > C. Or if you are OK with the subset included in MiWi (<=3D 1024 nodes, <= =3D = > 8 coordinators), use that. > = > So far, for home use, I have done (A) but lean toward (C) next. > = > For small commercial products, I would go with (A) since the FCC = > certification process scares me. > = > Hope that's of some use. > -- = > Timothy J. Weber > http://timothyweber.org > -- = > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D Ruben J=F6nsson AB Liros Electronic Box 9124, 200 39 Malm=F6, Sweden TEL INT +46 40142078 FAX INT +46 40947388 ruben@pp.sbbs.se =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist