So, now I hopefully(!) have my cable which will give me access to the UART RX of the CC128 energy monitor. Time to try it out and begin processing some data with it!

Firstly, I go to the XMOS website and get the UART code and play around with it to create the UART code I want (RX only at the moment), compile it and give it a run.

But it's never that simple! All I get are null characters. Odd I think - so I recheck the wiring, recheck the code. All seems to be ok.

So I strip down the code to a really simple function- one that just receives a character and prints it out (see the Super Simple UART receive function source file)

I still get null characters - maybe I got the wrong pins? Check again... nope, seems fine. So I decide its time to void the warranty (follow these CC128 teardown instructions at your own risk!).

Turns out there is a bit of solder between a via into the ground plane and the UART TX pin on the RJ45 connector (pin 8). After removing this I connected the XC-3 back up to the device and wah lah- it gives me the first character (a '<') of the XML data string.

Now to get the whole string out - so off I go to re-implement the more complex UART code.

After some battling I got it running!

The output looks like the following is in line with the CC128 XML documentation.

Next time... parse the XML and output to somewhere a little more useful!

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My energy monitor arrived today! It's working well - I was slightly worried about how good the reception would be for the transmitter, but I am pleasantly surprised that even with the receiver 3 floors above the transmitter it seems to register a good signal.

But that's boring - time to start hacking!

So, first thing I need is the interface cable. The back of the unit has a handy RJ45 connector that has serial in it (see my initial energy monitoring post). This needs connecting to my XC-3 kit so that I can begin to get the data out of it. So time to get the soldering iron out!

So, initially all I need are two wires from the RJ45 network cable (standard network wiring configuration)-

• Brown = the UART transmit (from the energy monitor)
• Blue = ground

I soldered the rest of them onto the strip board in case I wish to use them later and it keeps things neat and tidy.

For the moment I am using the the GPIO port on the XC-3, using pin 1 for a 1 bit port (XCore UART RX) and pin 16 is ground. This should give a good base from which to work. Eventually I would like to put it on the LED connectors to keep the GPIO free. The other bonus of using the LED connector is that the output side is buffered up to 5V which is what the UART on the energy monitor needs - though I think I will have a check of the Microchip PIC they use inside and see if it will take 3.3V logic levels.

Next time... getting data into the XC-3

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Was at a friends today and he showed me an energy monitor that he had bought and was using to monitor his electricity supply. I was like "hmm... this could be something fun to attach to an XCore and get some graphs out of".

My thought is to use my XC-3 (or maybe get an XC-2) to connect to an energy monitor receiver - or hack/make a receiver and then push the data somewhere useful via Ethernet. In fact I could combine it with my network monitor, ditch the screen and have it push the all the different types of data out into some nice pretty graphs. Anyway, enough brain dump - onto the hardware!

My proposal is to use a Current Cost Envi (CC128) device. There is a helpful CC128 write up from dale lane. It has several nice features:

1. The receiver has a RS232 output
2. The receiver outputs XML from the RS232
3. The system has support for up to 9 individual appliance monitoring (IAMs)

Some thoughts on software/graphing features:

• Display a comprehensive history (device can output real-time, or 2hr block data)
• Calculate some averages (particularly for time of day, month, season)
• Plot electricity use vs. temperature? - the relationship should be pretty obvious... but I like pretty graphs
• Plot the electricity generation stats and calculate my carbon footprint (ooh err!) - see Amee

Could even add some X10 stuff in there to... the possibilities are endless - watch this space!

Update: CC128 connector pinout- looks like you might be able to reprogram the internal PIC as well!

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