Accessing MySQL from Perl on SlugOS

May 27th, 2008

I’ve written about my CurrentCost meter that I’m using to monitor my home electricity usage, and the small home server that I’ve set up to collect the data.

Yesterday, I decided to make a start on collecting the data. My plan was to copy what Nick had done and create a MySQL database to store the info, with a table to store a timestamp and the watt reading from the CurrentCost meter. 

CREATE TABLE currentcostdl (  
    time TIMESTAMP DEFAULT CURRENT_TIMESTAMP,  
    power FLOAT NOT NULL,  
    primary key(time));

I started with Nick’s Python scripts, but didn’t get very far.

The server, a NSLU-2 (or “slug”) is running SlugOS.

The problem was that there is no python-mysqldb package in the SlugOS repositories. I did try downloading the source for it from sourceforge to build it myself, but struggled to get the dependencies I needed to make it – urllib in particular was a big pain.

I also tried the debian package but again dependencies on SlugOS got in the way.

So I gave up on that and decided to do it myself using Perl – Perl and MySQL had to be easier, right?

Erm… not so much 🙂

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Posted in code, tech | 7 Comments »

Writing C++ code to run from C# for .NET Compact Framework

May 25th, 2008

I mentioned earlier that I decided to write a DLL in C++ to invoke from my C# app for Windows Mobile. I’d not done this before, so thought I’d jot down a few quick notes about it.

I found a few detailed articles about this on MSDN that made for a good introduction to the topic:

There is a ton of information in these articles, so there isn’t much to add. Instead, I’ll give a quick, high-level overview.

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Posted in code | 3 Comments »

Programmatically searching for nearby Bluetooth devices in Windows Mobile from C#

May 25th, 2008

As part of my plan to write a location-based reminder app using Bluetooth devices, I need a way to know what bluetooth devices are near me.

I’ve not done any Bluetooth development before, so I’ve had to learn a few new bits and pieces tonight.

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Posted in code | 11 Comments »

Custom properties in Outlook Mobile

May 25th, 2008

As part of my plan to write a location-based reminder app using Bluetooth devices, I need a way to assign tasks to people, and people to specific Bluetooth device IDs.

I’ve decided to do this using custom properties in Outlook Mobile – the default PIM that comes on all Windows Mobile smartphones and PDAs.

I’ve not used this API before, but after a little playing, I’m impressed with how straightforward it all is.

The idea is that items in the Outlook Mobile PIM have pre-defined properties – so Contacts have fields such as ‘First Name’, or ‘Postcode’. But you can programmatically add new fields, and then store whatever you want in them.

For my purposes, I can add a “Bluetooth Device IDs” property to Contact items in my address book. I can also add pointers to Contact items to Task items in my to do list.

As this is just meant as a quick hack / proof-of-concept, I’m doing this in C#. The code looks something like this:

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Posted in code | 6 Comments »

Writing a Bluetooth-based location-based reminder app

May 25th, 2008

My bad back means that I’ve not spent too much time writing code for the past week or two. Tonight, I’m in the mood to try and hack something together.

I should probably try and do some work on my CurrentCost setup – now that I’ve got the new home server connected to the CurrentCost meter, I could write a script to start collecting data and do something with it.

But that can wait for another night – for tonight, I want to get back to doing something mobile.

One idea that I’ve had kicking around since last month is a location-based reminder app based around people – using Bluetooth as a way to know who is near you.

The idea was to have an application which lets you assign tasks in your Tasks list to Bluetooth device IDs for mobile phones and laptops. Then, when your phone sees that Bluetooth Device, it could remind you about that task.

For example, I could know that I want to talk to Will about a particular project. I can put this in my To Do list, but unless I’m actually looking at my To Do list when Will is around, it’s not very helpful.

But with this app, I set my To Do list to remind me to talk to him about it the next time I am near him – the next time his phone and/or laptop is within Bluetooth range, my mobile can prompt me with an alarm.

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My new home server – a NSLU-2

May 21st, 2008

I finished putting together my latest gadget this afternoon – a mini home server made from a Linksys NSLU-2 NAS device and a portable USB harddrive.

Why did I want it?

Do I really need an excuse? 🙂

Now I have a full, albeit small, Linux server at home, I’m sure I can think of some fun things to do with it. But as I wrote last week, the catalyst that pushed me to doing this now was wanting something to collect data from my new CurrentCost electricity meter.

It needed to be cheap, small, and low-powered – no point having a server running all the time to monitor my home’s electricity usage if it makes a significant dent in my electricity usage all by itself!

What did I buy?

A NSLU-2 – a network storage link for USB 2.0 disk drives, by Linksys. This is a small NAS device that lets you make a USB harddrive available on a network. The firmware in it comes with enough software to create a network share for any portable USB harddrives or USB flash memory key that you plug in.

It’s a neat little gadget, but what makes it special is that it is very easy to flash the firmware and replace it with a full Linux distro. Plug in your USB harddrive, and you have a Linux server with as much space as you might want.

Oh – and for some reason, people call them “slugs”.

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Posted in tech | 15 Comments »

Ouch

May 19th, 2008

Disclaimer: This is not a medical post. I’ve not referred to anything to write it, and I only vaguely understand what I’m talking about… if you are looking for medical advice, please look elsewhere.

My twitters for the past few days have mainly been moaning about my back hurting. I injured it last week, and have been out-of-action since.

I’ve been diagnosed today, so thought I’d share the full scale of my pain and woe with the world.

I have an annular tear in my lumbar region.

I’m trying to resist the temptation to google for this (seriously – that way madness lies!) but from what I remember of the doc’s description, one of the discs between the vertebrae in my spine has torn, causing the jelly (?!) inside to leak out. The jelly is what caused the muscles around the disc to inflame and spasm – a big cause of the pain I’ve been having since last week.

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Posted in misc | 3 Comments »

CurrentCost – first impressions

May 15th, 2008

CurrentCostCurrentCost has been a bit of a buzz going round Hursley for a few weeks now.

I’ve been resisting the temptation to get involved, because I know how obsessive I get about stuff, and I’m a bit busy at the moment to take on another new obsession!

But last week, I weakened. It was all looking a bit too cool, so I figured I had to give it a go.

I’m a few weeks behind the other guys at Hursley, so I’ve not got much to add that hasn’t already been said yet. Still, I have a few readers from outside the IBM group, so thought I’d share links to posts I’ve been following about what other IBMers have been up to, and add my first impressions.

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Posted in ibm, school, tech | 20 Comments »

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