I need to build a wireless network consisting of 20-40 nodes. System should scale up to 100 nodes if possible.
Network needs to support full mesh. Every single node needs to be able to emit broadcast events to other nodes, so that other nodes can do actions based on events. Also network should support directed messages to the specific node. Also BOM is a factor.
I was looking at NRF24L01+ specs and it's interesting. Only wondering 1:* feasibility. What I can understand from the datasheet, you can have up to 6 pipes. But it looks like you can configure the RX addresses per pipe. Could I specify one address(eg. 0xFF LSB) as a multicast address/pipe and when transmitting to that address, raise the NO_ACK flag? Would that be feasible?
Or can somebody suggest better solutions?
Any caveats I might have overlooked? (Not that much RF experience)
Some design points:
Low cost
Bandwidth needs to be sufficient to minimize transmission overlap. Traffic is not excepted to be very high. 2-5 messages / second.
Easy to implement, yet reasonable robust.
Indoors environment, some walls, max distance up to 40 meters. Average 10 meters.
(I'm implementing home automation for my new house if someone is wondering :))
The NRF24L01+ is inexpensive enough that you could experiment with it to see if it meets your needs. I am playing with a package that I received of 10 RF24's that I received from china. I am having difficulty using them with Nano. I will be trying to use them along with 3.3V regulators as they say that the 3V3 from the Nano is not enough to drive them.
At about 2 bucks ea, I'll play with them until I get them to work.... I also read that slowing them down to about 250K instead of 2Mbps will improve range as I have the PC print antenna. If you need extra range there are some with amps and real antennas that will go 2km.
Yes, true. Still hoping to cut R&D time, if somebody has already done similar things with this (or other boards). But as you said they are cheap (under $1 it seems) and surely going to test it out myself if nobody has better suggestions
But was surprised that the range is not "so terrible" and did not found how to do simple broadcast.
Then I tested RFM12B, works also fine but once again, no really meshed network library until I found panstamp. This is just Arduino clones with RF but they have a meshed protocol that seems to be really well done, all is open source and hardware, may be you could take a look, it seems very promising. The SWAP protocol for meshed networks looks great.
