Chips for wireless communication?

Question

Iron

Greetings,
There was a task to make a pair of autonomous wireless notification devices that should cling to a pair of contacts and, if they are closed, -> notify the central piece of iron / computer (it is enough to identify the transmitting device). There will be about 5-8 such devices and the size will not exceed 5cm x 5cm x 2cm. The radius of action is 10-15 meters.
Q:
* What wireless chips/technologies are on the market? Ideally, small, energy-efficient and self-sufficient - so that you do not need to put a mini-computer nearby for maintenance.

Answer 1

nrf24l01+

Answer 2

Well, nothing like that comes to mind ... Maybe an option like the XBee Shield v5 Nano is suitable? Here's another poke .

Answer 3

Rfm23 or similar. These are transceiver radio modules, code examples are easy to google.