killswtch.netA geek’s thoughts on various stuff

The CurrentCost power monitor has become very popular amongst amateur home automators and those technically-savvy who want to keep an eye on how much electricity they are using (and ultimately how much they are going to have to pay in bills). A couple of months ago I purchased the CurrentCost device and a USB cable to connect it to a computer from eBay. Having just seen their eBay store, it looks like they’ve got a fantastic new model on the way, but this article is about the older version.

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As promised, here’s the source code for my VAMS-0808 interface. It’s in C#, with C# projects included, and can be opened in Visual C# Express or full Visual Studio 2005 or greater. There are two test projects included – one which just writes status changes out to the console, and a WinForms project (which runs in mono) for full interaction.

Over a year after it began, the whole-house-audio project is complete. 4 rooms around the house can now be filled with the sound of any of (currently) 4 audio devices thanks to a mixture of hardware and software.

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The audio system that I’m building requires 2 low-power computers: 1 for the touchscreen controller (not using an iPod Touch for the moment) and 1 to act as a webserver and serial-console server.

Once again eBay has come to the rescue, and by searching for ‘geode’ – a low-power processor for Thin Clients & Small Form Factor (SFF) PCs – I found the 2 machines that I needed. These are the specs:

magnesium (the black one)

• 800 MHz Geode
• 256 MB RAM
• 6 GB CF drive
• Onboard graphics, audio, serial, parallel, USB & 10/100 ethernet

£70 + P&P

potassium (the grey one)

• 300 MHz Geode
• 256 MB RAM
• 6 GB 2.5″ IDE drive
• Onboard graphics, audio, serial x2, parallel, USB & 10/100 ethernet

£35 + P&P

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Yesterday I completed and successfully tested the control software for the audio system. The software works with the matrix switcher and the APC MasterSwitch remote control PDU to allow the audio output devices around the house (TV, radio, CD player etc.) to route their sound to any of the 4 audio zones.

I’m now waiting on some more purchases from eBay to arrive before I can finish the system off. On the way is a small touch-screen monitor and a low-power mini ITX computer to connect it to. This will function as the controller and will probably sit in the dining room at the centre of the house. I’ve not gone for an iPod just yet, since a small mobile device has the possibility of getting lost or damaged more readily than a fixed controller. I’m looking out for a cheap 2nd hand one on eBay though.

Although I had got the software working yesterday, I foolishly installed some updates for Ubuntu and now the serial ports have disappeared again. Rather than battle to get the ports to show up and behave I’ve gone a little more eBay crazy and bought a second thin-client-like low power PC which will run the matrix control software and possibly the web server for the front-end control interface.

The other remaining tasks include creating some more cables and positioning and attaching the speakers for zone 4, the master bedroom.

Full details of the setup, with a video, will hopefully be posted in the next few weeks.

Thanks to the chip manufacturer of the cheap serial port card, I’ve managed to get some extra serial ports working. If you can’t figure out how to get additional serial ports working, I recommend this guide [ZIP, 792KB] available from the Moschip driver download page. It should be valid for most models of serial cards, and explains how to add more than the standard 4 ports that most linux installs have.

Now that this problem is out of the way I can continue with writing the remote control software for the audio system.

Having put the 4 port serial card back into boron, the onboard port now works again, so I’ll probably continue with developing the software. The expansion card still doesn’t work though, so I’ve ordered a cheap 2-port card from eBay in the hope that a different card will work.

Before reinstalling the card I upgraded Ubuntu to see if that would help (it didn’t) which brought its own scary moment of the 1TB RAID volume being dead. That too is solved now – the drive letter assignments had changed.

Today I started development of the software to control the whole-house audio system. It’s written in C# and based on the MiniHttpd project – a small but powerful implementation of a web server in C#.

However, when it came to testing the first bits of code, I’ve envountered a problem. A while ago I bought a 4 port RS232 serial card to go into boron, because the motherboard only has 1 onboard port which isn’t enough for the UPS, the matrix switcher and probably some other things such as connections to network switches.

The new card shows up fine in lspci, seems to be ok when running setserial -gb, but when trying to send or receive data nothing happens. Thinking it might be a conflict with the onboard port, I went into the BIOS and disabled it. Still nothing. So I swapped the card into another machine and re-enabled the onboard port in boron‘s BIOS. Now the onboard port doesn’t work either.

I’m going to contact the manufacturer of the card for some help. But for the onboard port I’m completely stumped. It too shows up in lspci and setserial -gb (though only when running using sudo, which wasn’t necessary before) but any attempts to use the port result in various I/O error messages. I was worried that the new card may have killed the serial communication capabilities of the matrix switcher and the UPS, but I’ve confirmed that at least the matrix switcher still works by connecting it to my test machine, iron.

If anyone thinks they might know what’s getting on, please get in contact via the comments for this post – I would be very greatful for any help.

I’ve set up a few MRTG config files and some simple shell scripts to graph the available data from my Compaq UPS via Nut. This will give a basic way to monitor the combined power consumption of everything that’s connected to the UPS. Currently this is everything in the rack plus the computer under my desk (and the peripherals on top). If you like graphs, you can see them on this site.

In addition to this method, I also have a plug-in power meter that can be used on individual items. It’s currently plugged into the incoming side of the UPS. For whole house power monitoring, the Wattson looks pretty good, but it’s not exactly cheap.

An interface for MythTv on the iPhone (and presumably the iPod Touch too) has been developed by Chris Carey. It looks pretty darn cool. This saves me from having to write my own as part of the iPod Touch remote control project that’s planned. [Via Automated Home]