Arduino + wireless

What is the best energy efficient wireless module or technique that can be used for Arduion wireless projects. I came across ESP wifi modules, NRF24L01, 433MHz RF modules and Light blue bean devices.

What is the best choice for battery powered,wireless projects for long durations

What range?

Weedpharma

At least 20 - 30m range

What percentage of the time will you be transmitting data ?

...R

Robin2: What percentage of the time will you be transmitting data ?

...R

Its for a of room occupancy indicator. So it should transmit data only when a room get occupied. Transmitter side is inside the room. The indicators are outside away from the room (20m-30m) away.

Use a module that allows you to connect a directional antenna for the transmitter and receiver.

Andre_Leonardo: So it should transmit data only when a room get occupied.

I would not worry about the efficiency of the wireless module. Just ensure that is is switched off when it not transmitting. Each transmission should only require a few millisecs.

The trick is to design the receiver system so it won't miss brief transmissions.

The overall system will probably be easier to develop and debug if the transmitter sends a message at regular intervals to say that it is alive even if the room is unoccupied.

...R

What is the module you can suggest for me.

Andre_Leonardo: What is the module you can suggest for me.

If it was my project I would probably use an NRF24 module. But I have no experience of the 433MHz modules. And I don't know enough (anything) about the limits to the range of either type.

...R

Since you only seem to need 1-way comm's, the simple 315 or 433 MHz Tx/Rx modules with a Promini at each end might be all you need. Add a simple wire antenna, 23 (315 MHz) or 17 (433 MHz) cm long at each end. Run VirtualWire library on both ends, have Tx send unique data from each location. http://yourduino.com/sunshop2/index.php?l=product_list&c=12

Are you going thru a lot of walls in that 20-30m?