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Some basic questions about Zigbee and wireless

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2009/08/11 00:41:34 (permalink)

Some basic questions about Zigbee and wireless


I am trying to migrate from RS485 communication to wireless for my projects. I have decided to use the wireless module made by Microchip.

My questions are

1. Is the wireless communication full duplex. (ie: the module can send and receive at the same time), in the RS 485 single master network only the bus master could transmit while the slaves listened and transmitted only when asked for.

Is this the same for the wireless system???

2. Is it absolutely essential to use standard wireless protocols like MiWi or Zigbee etc ??
I am not sure these protocols could be accomodated on a small mcu like 16F648A or 16F88, so I may have to design one myself.

3. Can the module be housed inside a metal casing ???


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    RE: Some basic questions about Zigbee and wireless 2009/08/11 04:14:53 (permalink)
    Although i have not started work on the MRF24J40MA, i have heard that it works in a line of sight manner.

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    RE: Some basic questions about Zigbee and wireless 2009/08/11 14:33:20 (permalink)
    1) Usually, no, since the "air" is just one Smile the transmission is half-duplex. And if you use repeaters, it slows down the transfer rate...
    You could use 2 sets of channels to achieve duplex, but then you'd need 2 transceivers per side.

    2) No you can do whatever you feel with them Smile I'm a big expert of creating protocols! (no, I'm joking)
    Actually ZigBee is kind of a mess and would not fit on those small PICs.

    3) In my experience, range is always a mess so, no, metal enclosure is better avoided

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    RE: Some basic questions about Zigbee and wireless 2009/08/14 00:55:48 (permalink)
    Thought to help you with the few things i got to kw recently even though i am also begining with MRF24J40 module.
    1. Its not full duplex. You can achieve duplexity as DarioG proposed.., bt you need to have two tranceivers at a noed. Expensive , so Useless...!
    2. I no nothing to say abt protocols. But with PIC 16 family you cant store Zigbee stack. as i heard it neeeds 58k Memory to store. So it is good to use PIC like PIC18LF4620. See this Thread which i have started. http://www.microchip.com/forums/tm.aspx?m=438108 
    and also this..,
    3. Read the datasheet of MRF24J40MA modules mounting instructions. They specially mentioned how you have to aware of metal things keep away from the antenna. It will reduce your signal strength.
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