Get this stuff out of my head.

Teachers Needed to Help Make a RaspberryJam

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Do you know any teachers? Preferably ICT teacher of department heads or even school heads and education policy makers.

We’re trying to organise a RaspberryJam event for September, which we hope will introduce many educators to the potential that the Raspberry Pi has for positively impacting learning of STEM in schools and we need some input and advice from the people at the sharp end.  It won’t be too onerous, just come along at our next planning meeting on the 11th 14th of June - 6:30pm - 8:30pm in Sheffield (date change to avoid clash with France v. England match) and talk to us.  If you want to get further involved after that great, if not that’s fine too.

Teachers needed to help make a RaspberryJam

If you haven’t come across the Raspberry Pi yet, it is a very small (credit card sized), very cheap (£25), fully functioning computer. All it needs is an SDCard for storage, a keyboard/mouse and a TV to run all of the usual desktop applications.

It has been specifically designed to be used in schools as a platform to teach kids about computing and programming (rather than just how to use Word and Excel).  There are hundred of technologists playing with this new device to work out what it could be used for and getting very excited about the possibilities. However, as yet, there are not so many teachers who are aware of the Raspberry Pi.

Our conference in September will, we hope, introduce many, many teachers and other educator to the exciting possibilities of this device and address the practical issues that they will face when trying to bring it into their lessons. We imagine there will many questions to answer such as:

  • what sort of thing can I teach on them?
  • what lesson plans are already available?
  • how do I make these devices applicable to pupils of varying abilities?
  • can I teach things like creating social networking platforms but safely?
  • what about robots? Can I do something with robots?
  • how do I manage the devices?
  • what happens if the technology stops working? Can I call someone?

how can I use these just to teach things other than computing/programming? What about in science or maths lessons?

If this is of interest, please get in touch by email (  If you know someone who might be interested, please pass this message along.



image credits: artesea, widdowquinn, bkajino and the Raspberry Pi Foundation


Racism Stinks

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A few weeks ago I asked (on twitter) for ideas for simple Arduino project idea just to give me a bit of a challenge and get me started using my Arduino, which after being tinkered with for a week when I first got it had been sat in a box for over a year.

My friend Hannah Goraya (@yorkhannah) supplied a problem that was just the right mix of hardware hacky, coding and silliness to get me interested.  In her blog post she asked whether it it would be possible to train people to stop making racist comments in her workplace in the same way that dogs can be trained to stop barking by fitting them with a collar that lets of a pungent pong whenever they woof.

I thought that it would be entirely possible to implement such a system using one of those powered air fresheners that fires off (usually a revolting whiff of a chemical approximation to pine) automatically on a regular period.

The hardware hack
The first task was to buy one - a Glade Fresh Matic (not a ‘Sense and Smell’, which contains a motion sensor) - and take it apart.  With some a bit of poking about it became clear that all of the logic for the unit was built into a single chip on one of the boards.  A second board had the light sensor that feedback when the canister nozzle had been fully depressed, but everything else was hidden inside a single logic chip.  It did not look like I was going to be able to find an interface point to let me fire the spray from an Arduino.

Then I noticed that whenever the unit was switched on (using a simple slider switch exposed to the outside of the unit, the spray would always fire about 10 seconds later.  So if I could just control whether unit was on or off, I could cause it to spray when I wanted it to.  A little more poking (literally) about and a test with an ammeter proved to me that on/off switch was not a power switch but in fact a logic signal into the chip.  And even better, it required a LOW signal to activate so I wouldn’t even need to match signal voltages between the Glade unit and an Arduino.

Racism Stinks

The authorisation problem
As well as meeting the needs for Hannah’s racism training programme, I wanted to make my system as general purpose as possible.  I figured that it could be used at more public events, meetups and un-conferences.  In many of those circumstances it would not be appropriate to allow anyone on the Internet to fire off a pungent puff, so I needed some mechanism to say who should be allowed to fire the device.
I also wanted the management of the authorised user list to be done somewhere that doesn’t need technical Arduino knowledge to do.  It just wouldn’t work if to allow someone new to fire the spray you needed to reprogramme the Arduino.
The obvious choice seemed to be to use a twitter list.  These can be managed from any twitter client and are a logical place to manage a list of people whose tweets will be listened to (by the air freshener).  The only problem was that there did not seem to be an easy way to search a twitter list for a hashtag.
  • twitter’s search API only searches the whole twitter-sphere
  • doesn’t do any filtering over and above the twitter API
  • Yahoo! Pipes has some community connectors to Twitter but they kept falling over on me

The software service
My most viable option seemed to be to create a service that would do what I wanted. But I wanted it to be general

ised and reusable.  This meant that if I want others to use it I should be prepared for them to use it lots.  I needed to create the service on a platform that would scale and also not cost me anything when not in use.
The Google App Engine seemed ideal. Free for low usage, able to scale enormously if necessary.  Only problem - GAE doesn’t support any languages that I’ve written in before.  Never mind - how difficult can it be.
Surprisingly, for Python, the answer is not very.  In a few evenings I created a service that will search a twitter list for specified set of hashtags and return a true/false and a last tweet checked id.  It even allows someone to authorise it with twitter so that it uses their API request allocation (150 requests/minute) rather than one shared by the whole of the Google App Engine.

The Arduino bit
Obviously to be able to listen for and react to tweets, the Arduino needs access to the network.  I originally intended the Arduino to use a wifi shield so that, with a battery to power it, it would not need to be plugged in anywhere.  The cost of the wifi shields was just a little too much for me to fork out, so I went for a plain old ethernet shield.

After another few evenings poring over the Arduino library documentation and a lot of debug code, I created an Arduino sketch that does what I need it to:

  • initialised the Glade (makes sure it is not activated while the Arduino network is getting initialised)
  • initialises the Arduino network using the standard Ethernet/DHCP libraries
  • sits in a loop checking to see if it’s time to check twitter for updates again
  • calls the listhashtag service on appspot
  • capturing and remembering the last tweet check id (so we can ask for updates since then next time)
  • firing the spray if the hashtag was found.
  • rinse and repeat.

The Arduino code looks like this

#include <SPI.h>
#include <Ethernet.h>
byte mac[] = {  0x90, 0xA2, 0xDA, 0x00, 0x7A, 0x6D }; //must be set t the MAC address of your Ethernet Shield
int gladePin=9; // for testing purposes we're setting it to the LED pin
const unsigned long checkPeriod=60000UL;  // how often to check for tweets in mS
unsigned long checkAgainAt=millis()+checkPeriod;
char twitterCheckDomain[] = "";
char twitterCheckPath[] = "/saulcozens/racismstinks/badracist,racismstinks";
void setup(){
  // start the serial library:
  Serial.println("initGlade done");
  Serial.println("initTwitterCheck done");
void loop() {
  for(;;) {
    if(millis() > checkAgainAt) {
      if(twitterCheck(twitterCheckDomain, twitterCheckPath)) {
      if(checkAgainAt < millis()) { // this happens when millis() is near to rolling over, once every 51 days or so
void initTwitterCheck() {
  // start the Ethernet connection:
  if (Ethernet.begin(mac) == 0) {
    Serial.println("Failed to configure Ethernet using DHCP");
    // no point in carrying on, so do nothing forevermore:
    for(;;) {}
  // give the Ethernet shield a second to initialize:
char lastTweetChecked[22];
boolean twitterCheck(char* serverName, char* path) {
  EthernetClient client;
  if(client.connect(serverName, 80)) {
    Serial.print("connected to ");
    String request = "GET ";
    request += path;
    if(lastTweetChecked[0] != 0) {
      request += "/";
      request += lastTweetChecked;
    request += " HTTP/1.0\n";
    request += "Host: ";
    request += serverName;
    Serial.print("Requesting: ");
    String buffer;
    int i;
    while(client.connected()) {
      if(client.available()) {
        buffer += (char);
    String status_response = buffer.substring(0, buffer.indexOf("\n"));
    int body_p = buffer.indexOf("[") ;
    String body = buffer.substring(body_p);
    if(body.indexOf('[')>=0 && body.indexOf(',')>=0 && body.indexOf(']')>=0) { // we got all the bits we're expecting
      body.substring(body.indexOf('\'')+1, body.lastIndexOf('\'')).toCharArray(lastTweetChecked, 21);
      return (body.charAt(body.indexOf('[')+1) == 'T');
    } else {
      Serial.print("unexepected response: ");
  } else {
    Serial.print("Failed to connect with status:");
void initGlade() {
  pinMode(gladePin, OUTPUT);
  digitalWrite(gladePin, HIGH);
void activateGlade() {
  digitalWrite(gladePin, LOW);
  delay(20*1000); // switch Glade on for 20 seconds
  digitalWrite(gladePin, HIGH);  // then turn it off again

Meet Mr Stinks
After staring at the Glade Fresh Matic for long evenings of debugging it seem to take on a bit of a personality.  Its acrid emissions were disturbing even when I was expecting them and its disapproving manner made me think that I needed to give it a stern and severe look.

I raided the kids craft box and cut up some gaffer tape, 10 minutes later Mr Stinks was here!

Racism Stinks

Machine Readable

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I’ve been thinking about sharing and intimacy. Reading blog posts like Ben Hammersley’s speech to the IAAC, in which he suggests that far from being naive about privacy, the Facebook generation are very aware of that they are trading access to their lives in order to reap the benefits of sharing. And Martin Belam’s post on teens, privacy and Facebook. Martin gives some advice to adults on how their idea of privacy is not necessarily the same as their kids.

Then there is Bruce Sterling’s essay on The New Aesthetic. Now I am not about to claim that I understand all of Bruce’s essay or have worked out what the New Aesthetic is all about yet, or even what Bruce is suggesting the New Aesthetic is (or should be), but I took one thing from his post and that was that the notion that computers can think, can make judgements, is a generational thing. Kids today are not scared that the machines will become self aware (and send robots back in time to destroy us all).

All of this started me thinking about my own strange attitudes towards privacy and anonimity.  I like being online almost all of the time. I share, primarily on Twitter, detail about my life, my family and my thoughts. I use my real name, my kid’s real names. I check in on Foursqaure. My life is available for everyone to see.

However, when I leave a conference or workshop while still wearing my name badge, I am mortified. For the people I walk past to know my name or my business embarrases me.  It seems that while I have no problem with being visible to the machine or to being judged by people in my networks, but when in close proximity to people I become somewhat more private, more protective.  This is a contradiction that intrigues me. I suspect this may be a related to insecurities about physical appearance - will those people I pass think I look fat or worse still uncool!

Never one to leave a scab unpicked I decided to make something (New Aesthetic anyone?).  I created some short links ( and and created QR codes for each (put ‘.qr’ on the end of any URL).  Then over to to pick a garment.  

Of all of the available T-shirts, sweatshirt and boxers on offer, it was the hoodies that made the most sense.  A hoodie is specifically designed to provide anonymity and privacy when in pubilc - especially from the prying eye of the machine, the ubiquitous CCTV cameras.  This is not an academic exercise, I need to wear this thing so I figured that a zipped hoodie (a zoodie apparently) would suit my generous proportions better.  A bit of image manipulation later and the application of a suitably retro typeface and my machine readable hoodie is ordered.

Expect to to see me wandering around town. But if you do, be sure to tell me it looks cool.

You probably scanned my front.

machine readable


You probably scanned my back.

machine readable