2.4 GHz versus 434 MHz transceiver for home automation

As you describe it, with one way communication from a single master to many "slaves", the task is very easy.

The master simply sends messages of the form Address + Data. All slaves hear all messages and each slave checks for message with its own address and actions them while ignoring the rest. As the master has complete control of the transmitting this can make very efficient use of the channel capacity (when efficiency is needed).

·__________________

If you want to go the other way and have many "outposts" sending messages to a single central location in response to messages from the Master (usually on a channel of its own) "the fun begins". Out of such a need has risen much of the data comms protocols that we see today, and the internet.

The (or a) classic early initiator was named "Aloha Net" ("Hello Net") operated by the University of Hawaii to outposts around the islands. This used the simple method of an outpost "just sending a message when it had one". If it did not get an acknowledgement within a certain randomly set time it would send it again. This allowed for radio fade and noise and collisions with other messages. This works well when the total message transmit time is a small percentage of the tome available and when message lengths are short compared to time between messages. This would often apply to home automation applications, allowing an easy two way communications protocol when you find you need or want two way commiunications - as you soon will :-).

That module gives you low level access to the radio -- e.g. you're not going to be sending high level prototcol data. Yes -- it's trivial for you to send any arbitrary message to the radio and have your arduino interpret the message as you please (set pwm duty cycle etc). You shouldn't need to do a whole lot else to get proof of concept. If you need super long range 0 dBm might not cut it, but it's definitely OK for several meters.

With regards to your second question: there are a million ways to identify the different radios. The most expensive and worst way is to have a different transmitter for each receiver. It's obvious why this is a bad solution. All your other solutions will require you to implement some kind of higher level protocol. There are lots and lots and lots of options here (this is a whole area of academic research). I used a similar Nordic radio several years ago and it had different channels you could utilize. That can help you (e.g. put one receiver on one channel), but it obviously doesn't scale well (e.g. if you have more devices than channels you're back to square one. Equally importantly you might not want to use certain channels -- they might be noisy, have poor PRR, etc). One simple, but not particularly robust (from the networking perspective) is to invent a protocol wherein you blast a message and depending on the contents of that message one and only one receiver responds. Your arduino will have to implement whatever protocol you want so obviously you can't go crazy with the complexity (e.g. you probably don't want to implement posix sockets). For a few motors (less than 10) you'll probably be OK doing something like this provided that you don't have stringent latency requirements.