[TriEmbed] NRF24L01+ Based Large LED Array control

[Michael Fulbright]

I've been following the large scale building lighting project and it 
sounds cool.  I was thinking about it some driving home today and 
wondered if the simple NRF24L01+ modules wouldn't work.  These are $1 
each and have the typical 30m indoor range (depending on walls, etc) and 
can be run between 200 Kbit/sec to 1.5 Mbit/sec as I recall.  I use them 
for remote sensors I built and put all over the house.   They work at 
2.4GHZ as I recall.

I would think you could have a master at the base level of the building 
and each "refresh cycle" for the display you would have the master send 
a message which encoded the display contents (which building levels are 
on/off).  If all of the lighting nodes would just be listening nodes so 
this is easy.  The first floor light will receive the message from the 
master, put its light in the correct state, then temporarily go into 
xmit mode and repeat the message, then return to listening mode.  The 
second floor would either have already received the masters message or 
more likely the repeated message from the 1st floor.  Then goes on until 
the final floor receives a message.  It would take a little 
experimenting but I think you could easily support a refresh rate of 
several HZ using this.  The nice thing is you can add as many nodes as 
you want and as long as the message encodes each nodes state then you 
really have no configuration except teaching each node what its address 
is (so it can pick out its state from the message).

The message could be a simple bit-encoded state array so it would be 
quick to xmit.

Just an idea based on some things I've played with.  The NRF20L01+ 
modules have fairly robust support for Arduinos so you could get the 
cost for a single node down to almost single digits if you use really 
cheap Arduinos (not including the cost of the LED strip controller, but 
that is a fixed cost we can't control).

Michael Fulbright