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I'm going to work on a project in which I need to take your experience into consideration to which path should I go to.

I need to design a wireless circuit at max size 5x2 cm, that has a thermostat and a MCU. I need to cover an area of 1km, so I would go for the ZigBee approach. There is also a design problem with battery life, so I need also to have the least power consumption that can be done.

Do you think with that design specs, is it possible or no?

So in general I would care about:

  1. Low power

  2. Size

  3. Cost

  4. Transmission range

Update:

I have found this chip, the CC2543/44. How do you like it and is it suitable for my design?

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For lowest cost I would recommend a simple ISM transmitter (frequency will depend on where you are (which freq is allowed)). A quick search on digikey.com will point you in the right direction.

Some more detail needed:

Is data going to be one way always? Is there more than 1 transmitter per receiver?

What is the required battery life?

This is type of application where energy harvesting is great, perhaps research this and include a rechargeable battery - although this will increase the board cost significantly.

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  • \$\begingroup\$ 1. Yes the data will be one way always 2. Yes there should be many transmitters and hopefully one receiver 3. Battery life should stay for 3 years or more if that is possible \$\endgroup\$ – Ahmed Saleh Mar 15 '13 at 23:11
  • \$\begingroup\$ It might be possible if you can come up with a way to ensure each transmitter transmits in a specific time slot. You wouldn't have to worry about this if you use a system like zigbee but then you have a master - slave relationship were your device will have to be always in reception mode - wasting power (some systems acheive lower power by sampling periodically - like Coronis Wavecards). Similar systems I have seen use at least 3 'D' cells to last a number of year so are quite large. \$\endgroup\$ – Mark B Mar 15 '13 at 23:21
  • \$\begingroup\$ I'm not worried about the receiver power consumption, just the transmitter. Does the 2.4Ghz antenna should be that large ? I just need a small wire like 2CM maximum... \$\endgroup\$ – Ahmed Saleh Mar 15 '13 at 23:36
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Several questions come to mind:

  1. How many readings per unit of time? Regular interval reporting or threshold based?
  2. Standard compliant (Zigbee, IPv6Lowpan etc) or proprietary protocol?
  3. Standard MAC (802.15.4) or proprietary?
  4. What kind of batteries? Rechargeable? Coin cells?
  5. Which ISM band? 2.4? 915? 868? perhaps 433 or 315?

All those will dictate your design choices and constraints, and for most of the variations there are ready made reference designs, mainly from the radio IC manufacturers. (TI, Nordic, Semtec, Atmel and others).

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  • \$\begingroup\$ 1. I want for every 30mins a one reading 1 byte of a temperature 2.Zigbee is better 3. I need a battery of watch 4. I think band depends on the range ? so the best range with the smallest antenna because of the size of the board ? \$\endgroup\$ – Ahmed Saleh Mar 15 '13 at 21:30

protected by W5VO Mar 16 '13 at 13:39

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