microcontroller based sensor project: ZIGBEE vs GSM

My application will be having many microcontrollers with sensors monitoring a large area. The application requires all these microcontrollers to send the data to the master microcontroller. From the ma开发者_JS百科ster microcontroller the data must go to desktop PC via serial connection and to a mobile application. Which one (Zigbee/GSM) will be suitable?

This completely depends on what you mean by "Wide Area." A few hundred square meters? A few hundred square kilometers? Zigbee is more cost effective and simpler to implement if you're within range. You could even mesh your nodes together to extend the collective reach of your network. Otherwise, well, you have no choice but to use something like GSM.

RF Line-of-sight range on readily available XBee Modules can be up to 2 miles. Higher power models can be had with 40 mile LOS range.

If you are within range, I would recommend ZigBee as that saves you the cost from having a sim-card in each device.

Buy zigbee modules that have SDK and HW ability for mesh networking. That will give you ability to talk to far nodes via routing nodes. Unfortunately zigbee can not do adhoc mesh networking so you need to know in advance what your routers will be, or to program your nodes routing your self. Another 802.15.4 module (by Synapse) can solve all this since it supports ad hoc mesh networking for you via SNAP protocol. It is not zigbee compatible, but Synapse modules are already adopted by big players like Garmin so this should not bother you. They also run much longer on batteries then zigbee modules. They can also give onboard analog and digital IO accessible without need for additional MCU (although you can connect it and give control to it if you wish). There is also USB stick that will enable your PC to talk to these modules.