----------
dfinvrelay
----------

The SMA 3000HF inverter has a Bluetooth interface that can be used to pull out
various statistics, but my computers are on the other side of the house, too
far away to talk to the inverter. Rather than move the computers, I built a
little box using a Seeeduino Stalker (Arduino), Bluetooth Bee and a Wifly to
talk to the inverter and upload stats directly to pvoutput.

Bill of materials
-----------------
- 1 x Seeeduino waterproof kit (I used v2.0, but should work with v2.1)
  (http://www.seeedstudio.com/depot/seeeduino-stalker-waterproof-solar-kit-p-911.html?cPath=138)

- 1 x Bluetooth Bee
  (http://www.seeedstudio.com/depot/bluetooth-bee-p-598.html?cPath=139_142)

- 1 x Roving Networks WiFly with wire antenna (PCB antenna should work too):
  (http://www.seeedstudio.com/depot/seeeduino-stalker-waterproof-solar-kit-p-911.html?cPath=138)

Code
----
The SMA protocol is closed, and there are no documents freely available that
describe the entire protocol. There have been a number of efforts to reverse
engineer the protocol. I have taken liberal amounts of code from
Stuart Pittaway's nanodesmapvmonitor project available at:

https://github.com/stuartpittaway/nanodesmapvmonitor

The rest, blame me.

Dependencies
------------
- Arduino Time library:
  http://arduino.cc/playground/Code/Time

- Arduino SoftwareSerial library:
  http://arduino.cc/hu/Reference/SoftwareSerial

- Narcoleptic sleep library:
  http://code.google.com/p/narcoleptic/

- TMP102 temperature library from Seeedstudio:
  http://seeedstudio.com/wiki/Seeeduino_Stalker_v2.0#Source_Code_Examples

Caveats
-------
The project only implements a few messages of the SMA protocol, enough to
get stats up to http://pvoutput.org. Check out Stuart (and other's) efforts
for more of the protocol.

Arduino 1.0 builds the code to about 18k, which is at least 2x as big as it
needs to be, but I wrote this in a hurry.

Some leftover cruft from testing on the computer is in the code - this is
marked with #define DESKTOP.

I duplicate the SMA and BTBee addresses between sma.ino and bt.ino.

At one point I was getting some clashes between the hardware and software
serial libraries on read()s; adding some small delays in the serial read()
seemed to tidy these up. Should look at the interrupts, but like I said,
I put this together in a hurry.

The Bluetooth bee is put to sleep by manipulating pin 5 on the Seeeduino
Stalker. There is a track you have to cut on the board in order to be able
to do this; read the Stalker specs for details.

Somewhere in the SMA user documentation (or somewhere else, probably Internet)
it states you can only have two Bluetooth connections to the SMA inverter
at once. You can run into problems if you don't disconnect the BT bee after
making a connection - typically you can't connect again for some sort of
timeout period. It's a bit frustrating, but give a minute or two between
your connections and you should be fine.

Other stuff
-----------
My solar feed is available at:
http://pvoutput.org/list.jsp?userid=7398

If you use pvoutput.org, please consider donating (unaffiliated):
http://pvoutput.org/donate.jsp

More information on SMA products (unaffiliated):
http://www.sma.de/en

Have fun!
Dean