Jamie Bennett Speaks

So, it seems that everyone is making their new years resolutions around about now, I guess its my turn. In no particular order.

Wow, that was a long list and I still have more that I would like to do. I will commit to the above list and aim towards the many other things I would like to do.

Lets hope 2009 is a great year for me, and of course all of you too!

To carry on my initial education with the CurrentCost unit, last night I played around a little with RRDTool using Paul Mutton’s tutorial. I must say I’m pretty impressed with the outcome.

Last nights power consumption

The output above is from last night, starting around 19:50 and ending around 06:45 this morning. The peeks at the start of the graph are the dishwasher, the sustained 500w or so afterward are the XBox 360 being used to stream video from my Linux box.

The peaks early morning are the rumblings of the family, using the toaster and kettle and generally going about our morning routine. The only unexplained part of the graph is the increased usage around 23:00 until around 03:00. My only guess is that its the laptop charging the battery and at around 03:00 is was full?

At rest, the house with laptop, CurrentCost meter, fridge freezer and small night light for the kids, sits at around 65w.

The next step is to interface the CurrentCost meter with a spare Beagle Board I have sitting idle. The Beagle Board draws just 2 watts so it seems like the perfect partner for this experiment.

I received my CurrentCost unit today from the Eco Gadget Shop. I’m impressed with their service, it only took a few days to arrive. Anyway, as soon as I unpacked the unit and installed the cable grip, it was time to have a play.

As any self-respecting Linux geek would do, the first thing I did was try to hook the unit up to my Ubuntu Intrepid Ibex box. Theres quite a bit of information out there on logging the data that the CurrentCost unit spits out but most of it tends to lean towards the Windows/Mac OS X side or concentrates on the serial port interface of the older cables. What I wanted was a Linux and USB serial cable solution.

The first thing you need to do is setup the USB serial cable. This is pretty trivial if you know what you are doing but can be quite daunting if you don’t. First plug in the USB cable and verify that it has indeed been recognised.

A lsusb should show something along the lines of this (your output will vary but the important bit is the part that reads:

Bus 004 Device 002: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port

Take note of the ID, its in two parts, the 067b bit and the 2303 (your numbers will most likely be different). Then its time to modprobe the USB serial driver in.

Notice that the two numbers from the previous command have been used with a ’0x’ added to the front of them. Issuing the dmesg command should show you that the USB serial driver has been loaded (look near the end of the output) and that /dev/ttyUSB0 is now available for you to read.

From this point on I really recommend you read the excellent how-to by Paul Mutton over on his website. The perl script he supplies only needs two lines changing. Change:

my $PORT = "/dev/ttyS0";

to

my $PORT = "/dev/ttyUSB0";

and

$ob->baudrate(2400);

to

$ob->baudrate(9600);

The first change is to point to the USB serial port and the second to set the baud rate to the newer units speed of 9600.

The rest of Pauls how-to will get you up and running, logging the data and producing nice looking graphs.

I’ve just installed ScribeFire to my Firefox browser to make it easier to blog. So far I’m pretty impressed to say the least. There are not that many blogging tools out there that integrate well with Drupal but ScribeFire is one of them. Well worth checking out if you have a Drupal, or any other kind of blog.