I have a data logger board with a SIM808 on it. It has Bluetooth 3.0 capability by the SIM808. The board itself implements a battery management system, capable of performing weight, humidity and temperature measurements and also can detect device displacements. All collected data is transferred by GPRS connection to a remote server.
The device itself can be installed into beehives, but it would not be cost effective to have a SIM card for hundreds of hives. So this will only act as a master, that have data logging capabilities as well beside the GPRS capability.
Thus, I am planning to implement slave boards without the SIM808 modules. So instead of the SIM808, a simple wireless communication unit is needed to enable local, wireless communication between the hives.
The master would query all the slaves for their data, and then it would transfer everything via GPRS.
It should look like this, only with a hundred hives:
Now the possibilities for local wireless communication:
- Bluetooth, as I said the master device already have Bluetooth 3.0. But I am not entirely sure that Bluetooth is the right way to query a hundred slave for 1 kBs of data.
- The master device has an I2C bus, so I can connect I2C compatible ZigBee or other RF module which could be added to the slave boards as well.
Collectable data from slaves won't exceed 1 kB/query.
So all in all can I stay at Bluetooth or should I add ZigBee for example to my devices or are there any other options?
Some more details:
- range is max 30 meters
- also as the devices are battery powered, a solution with low power consumption would be good
- the master would run a query in every 15 mins
The main goal is to make the master able to query the slaves efficiently, and this should be done without modifying the PCB of the master. The two possibilities are Bluetooth 3.0, which is already available for the master, or other technologies that I can connect to the master board via the I2C bus of the on-board MCU. (I do not insist on using Bluetooth, it was the starting point because I already had a BT 3.0 by the SIM808.)