I am trying to connect multiple atmega328p with wireless module which can each send massage to the receiver. Most important is we need save as much battery we can.
I want know which one of the Below wireless will work for me:
You may be able to save battery on the Tx by turning it to sleep mode except when required.
The Rx would need to be constantly awake to be able to detect any Tx.
You also have the problem of two Tx sending at the same time. Depending on how often the data is required to be sent, it may not be hard to overcome by sending the data twice with a random time in between.
Thank you for feedback, Rf is good but since the whole device is very small and can not add external antenna to it I do not think it can go as far. I know wifi power hungry but you do not need receiver you can just used computer.
I think the best option for power is Bluetooth 4.0. The latest modules like HM-10 take sub milliamps and in certain power save conditions will go down to uAmps.
The "official" range for BLE 4.0 is 100-120 in best conditions.
But they are not multipoint-to-multipoint.
If you need many-to-one you could still do it, having many clients connect to one single "end" point.
The sell for $6 on ebay
Be aware there are some clones (know as CC41-A) that seem to lack some of the capabilities in the HM-10, and you don't save $1 with them...