Seb Holzapfel [Legacy Post]

Anything I've marked [Legacy post] means this post has been imported from my old website and is probably really dated :D.

The Void 15 posts


A need for read

About a year ago I purchased an ‘atomic IMU’ unit from Sparkfun ( for completeness, an IMU is an Inertial Measurement Unit, providing readings in (usually) >= 6 dimensions of global and angular acceleration ). Since then, I have used it in a few projects – a gyro mouse for a virtual reality headset (link), measuring the deceleration of a toy car for a physics demonstration; and as a nice test data-source for serial communication fiddling. Recently I had familiarized myself a little with the PyQt GUI framework, and was in a search for small project ideas to reinforce what

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Playing with Javascript

School productivity

Our Software Design lessons at school have always been competitive, classmates competing for the shortest code, the most interesting project ideas etc. The fruits of one of these unofficial ‘competitions’ though, I think is worth a write-up; the JavaScript Challenge. The challenge was to create animated, interesting graphics in JavaScript using only ASCII characters. Classmates probably wouldn’t be too happy if I stuck their submissions online, hence I’ll only supply my own. With all due modesty though, the nearest competitor was a white spiral generator, which didn’t animate – so you’re not missing out on

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Beginning year 11 my electronics workbench was quite decked out; the only thing missing was a decent DC power supply. Reading around online, good ones with decent range and constant current capability were going to set me back at least 150$ (quite a lot for the cash-strapped student I was!); so I decided to make one.

After a few weeks of spending the odd school afternoon perfecting prototype circuits, simulating, and slowly piecing a master-circuit together, I had a working schematic.The following weekend I layed out a PCB in EAGLE and sent it off to iTead Studio to

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4-bit Pic24 Alphanumeric LCD library

Looking all over the internet, I could not find for the life of me any existing Alphanumeric LCD library for the C30 compiler – so I made one, which requires 6 pins to operate. It only has 3 commands; lcd_print, lcd_command and lcd_init. For printing anything more complex than a string, the standard library can be included and sprintf is used to format a temporary string to be sent the LCD’s way. Files here are tested on a PIC24FJ64GB002, MPLAB X 1.10, C30 3.30c.

An example main.c file – Flashes an LED while displaying a

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Atomic IMU and some C++: A Generic VR system.

I began to re-cover the topic but never finished the process. Maybe next holidays given more time. In the meantime you can watch an ancient video of it working at the bottom of my old post.

Using an Atomic IMU from SparkFun, some Video Glasses from ebay, Some C++ and some duct-tape; a while ago I hacked together a Generic VR-type system. In this video I explain how it works, what I’m up to, and what I’m planning for it:

A class for constructing from raw IMU data, checks validation and combines bytes:

struct IMU_Data {  
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TextSweeper - A Minesweeper that has gone console

In all the time I spent at work experience with DPI IT (which was awesome, by the way) – I had a load of free time; in fact, in the 5 days I had there, there was about 7 hours of just sitting there doing nothing. My attempt at turning this time into something productive was this:


Basically – it’s just minesweeper but it runs on console:-

Download it here (includes source)

(inside the archive is a ‘bin’ folder, the executable is in there) Download is half a meg – but that’s only because of the bloated VC++ dlls

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D.I.Y Virtual Reality - A gaming interface?

This is an old post on the topic and I have completely re-covered it here

A little Backstory

A couple of months ago I began building a VR-type system (headtracking, HUD etc), with the (rather ambitious) requirement that it would be able to interface into* any game that I throw at it. *I succeeded (mostly), but before I get into that, I’m going to give some story of how it came to be:

V.R – For Noobs?

I first came up with the idea when I (by chance) came across these MyVu devices on eBay:


Myvu Personal Media

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