• Category Archives Hardware
  • Cardio Grapher Beta

    As hinted at in my previous post, I’ve been working on an Android application in my spare time for the last month or so.

    As a result of me no longer being a student I can no longer go cycling so easily during the middle of the day when there is daylight and the roads are quieter. When winter has passed so I don’t end up cycling back in the dark (multiply the distance by the number of working days the journey would be in the dark for and take into account the fact it would be at rush hour and on busy roads and that’s quite a lot of risk to accumulate) I’ll get around this by cycling to and from work (I did a few times before winter set in). But for now I’ve bought a turbo trainer for my bike and have it set it up in my flat.

    Now, necessity is the mother of invention and as with many of the things I’ve built this was the case here; when cycling out on roads I’ve used Google My Tracks a lot (and even added a small feature at one point), but when inside it becomes a lot less useful – obviously all distance and speed data (derived from the GPS) become meaningless. Now, I could setup a standard magnet based cycle computer on the rear wheel, but even then the data are not so meaningful – knowing that you’re doing e.g. 20 mph when stationary doesn’t really give you any idea how you’d be doing out on roads. So heart rate really does become the metric of real interest.

    Of course there are numerous applications out there already that will connect to the Zephyr HxM (the Bluetooth heart rate monitoring strap I bought) – for example, My Tracks itself has support for a wide range of sensors – but the majority of them share the problem that displaying heart rate is only one the things they do and as such little emphasis is placed on doing things with that metric other than graphing it and giving the current value.

    Enter Cardio Grapher: While it doesn’t yet do that much more than the existing solutions, my intention with it (as you may guess from the name) is for it to solely work with heart rate data. As such, I intend over time to explore a number of ideas for metrics that can be used to gauge the quality of a workout and to track progress.

    Today I’ve released version 1.0, which I consider to be beta quality. The features:

    • Live graphs of your heart rate over the last 1, 10 and 120 minutes.
    • User specific heart rate training zones, helping you get the most you can from your training (based on formulae from http://www.machinehead-software.co.uk/bike/heart_rate/heart_rate_calculator.html).
    • Audio alerts when entering and exiting training zones.
    • Can be set to keep the phone’s screen on when in use.
    • Can be set to automatically switch the phone’s Bluetooth adapter off and on again when connecting to the HxM times out (this is a work around for a bug in the Bluetooth implementation on some phones).
    • Reports the remaining battery charge level of the HxM.

    View it on the Android market here: https://market.android.com/details?id=net.cardiographer

    Screenshots:

    Connecting Autoscaling Training zones Details About EULA Preferences Menu

  • De-dust

    Back at home for Christmas, I was required to clean out a computer the other day. It was pretty bad:


  • Fractal Design R3

    Very nice case; the best I’ve owned and pretty quiet too.


  • i7 Machine

    The last time I owned a desktop computer was either April, May or June 2007. I sold it in one of those months so I could make the last payment to Team Challenge and go to Malawi for a month for a mixture of project work and trekking. It really was a great time with a great team. For the last two and a bit years then, I’ve been without a desktop machine and have just had a laptop, which until now has catered for my requirements quite well. However over the last few months my requirements have changed such that the laptop wasn’t really cutting it. I would have replaced it with a newer laptop, because they are smaller, lighter, quieter and generally unobtrusive in that way. I then realised just how significant the price difference for a given specification is between laptops and desktops and decided to instead build a desktop. So, last Monday I ordered some parts. They arrived last Tuesday and I put them together between various other things like supervisions. It would be fair to say it has a little bit of memory. I’ll have to make it last a good few years!

    Pictures:


  • iBantumi (electronic Mancala game)

    Once again (and this is the last one in the series!) this post is a Systems & Control coursework of mine from a couple of years ago – my A2 major project (November 2007 – April 2008). I’m publishing now because publishing my own coursework while still doing the A-Level it was for wouldn’t have been a good idea.

    I would recommend having a quick flick through the full documentation – read the whole thing if you want but you probably have a lot of things that are more worthwhile!

    iBantumi was the name of the major project I did for the A2 part of my Systems & Control A-Level. Over the summer between AS and A2 Levels, I spent a month in Malawi on a Team Challenge expedition with people from school. While there I discovered the family of Mancala games and bought myself a wooden Bao board. The games are great, but particularly with some variants you can end up spending a lot of time doing repetitive seeding. It was in fact while I was still in Malawi on the expedition that I decided I would make an electronic board to automate some of the more repetitive parts of play for my A2 project, and so I created iBantumi.

    iBantumi as the name suggests is an electronic version of a particular Mancala game – Bantumi which I had played years before on my Nokia 5510 – rather than the slightly larger and more complex Bao (like the wooden board I had bought). Initially I planned to recreate Bao but I would have required in excess of a thousand LEDs to do so, which I thought perhaps a little unrealistic for an A2 project given the time constraints and limited equipment (would have needed to go surface mount for that really). Bantumi is a simpler game, so I only required 336 LEDs for iBantumi.

    At the heart of the project are 14 Microchip PIC16F882 PICS programmed in assembly to function as serially controlled “pit registers” – essentially allowing me to control the 336 LEDs individually over one wire from the main controlling PIC – a PIC18F252. The LEDs are grouped into pits of 24 LEDs. The main controlling PIC was programmed in C. The beauty of iBantumi is that the player only has to choose which pit to initiate their turn with and the main controlling PIC will then automate the rest of the move.

    Reflecting on iBantumi as a project, my time management of it was significantly better than that of the f00n DS4 - I finished most of the project a few weeks before the deadline, leaving me a decent enough amount of time that I should have been able to develop a decent computer player and LCD menu system for it. Unfortunately the PIC18F252s I was using as the main controlling PICs all failed at about this time in a way that meant I could not flash new programs onto them, effectively ceasing development entirely until I was able to buy some more – which happened to be the day before the deadline. I knocked up an AI player in the lunch hour of the deadline day but was unable to do anything about LCD menus, so the LCD remains unused. I got full marks for the project.

    I designed the case using PTC ProDESKTOP, which was very useful in allowing me to cram everything into the smallest case possible without interference between components. Some of the photo realistic renders are included in the pictures below.

    Warning – the documentation is by no means lightweight, but should be a brilliant guide if you want to build something similar out of the same components.

    Full documentation: iBantumi (electronic Mancala game) (99)

    Pictures:



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