Software Upgrades and Theft

I'm away from home. Network connections in the hotel are a bit dodgy. I'm giving a talk at a technical conference where I'll be expected to have the brightest and latest software on display. And so of course the latest Windows Phone 8.1 release becomes available to me today.... 

So it was off to Starbucks for a coffee, some quality wifi and a firmware upgrade. It took a little while, but it is a tribute to the phone team that it all went swimmingly well. All my applications, media and settings made it across the upgrade and everything is where it should be. And there are some lovely new things to play with.  

This is just outside our hotel. Very nice.

Once the upgrade was complete we headed over to the station and caught the train to The Hague. 

And somebody stole my suitcase. 

It seems that there is method behind the constant "Don't leave your luggage unattended." messages that they play at stations and airports. Because if you do it will probably be stolen. This put a bit of a downer on the day, although all the miscreant got away with was a bunch of over-sized clothes, some dirty.  All my technology was in my backpack and that never leaves my sight.  The good news is that the hotel is splendid, and while we were out looking for replacement clothes for me we found a smashing little town centre just a short walk from where we are staying. 

Beer and Culture

We started off today with a trip to the Rijkmuseum. They have some superb pictures here, including the Night Watch, although it was a bit busy.

After lunch we headed for the Heineken Experience, a somewhat less cultural experience, although it did involve yeast. Fun fact of the day, the text in the Heineken logo was adjusted to create "smiling e's".

This probably doesn't improve the flavour very much, but it makes the brand look a bit happier.

Heading for TechDays via Amsterdam

Thunderbird Three at Humberside Airport. Who knew?

We are having a day or two in Amsterdam before heading off to TechDays in The Hague. So we hopped onto to the plane at Humberside and headed off to Schipol. After a quick train journey we checked into our hotel and then headed out for a walk. Of course I took the camera.

There are a lot of bikes here

Tooltip from Amsterdam...

I really do like it here. 

Nest Controller

I've fancied having a Nest controller for a while but they've only been available in the 'states. Then this week I found out that they are now out in the UK. It's taken a while for them to arrive here, mainly because of the differences between US and UK heating systems.

Mine arrived yesterday, complete with a set of instructions on how to install. I'm very tempted to have a go, but this would probably be a daft thing to do just before we go away for a week or so. But I think it will make a nice Easter project.  

Plenty of Bluetooth

If you want to connect your Windows Phone to any kind of hardware I can strongly recommend the HC-06 Bluetooth adapter. I've found it to be very easy to connect to and it works "right out of the box". It plays a major part in my TechDays presentations. You just connect the devices to a power supply (from 3.3 to 6 or so volts) and then your device (usually an Arduino) can talk to the adapter over a serial connection which by default is set to 9600 baud. 

The connections to the device are only supposed to work at 3.3 volt levels but I've had no problem using the 5 volts signals that the Arduino produces. 

You can change the name of the device by sending it commands, but you can pair any number of them with a single phone and then when your program runs it will connect to the first one it finds.

You can find these devices very cheaply on places like eBay. Search for "Arduino HC-06" and you should find quite a few. If you are prepared to wait for them to arrive from China you can get them very cheaply, but beware of buying ones marked as "carriers". These are very, very cheap but they actually don't have any chips on them...

Pretty Lights for Tech Days

I'm just getting the hardware and demos ready for TechDays next week. I took some pictures of the coloured lights. I think this one came out quite well. 

Rainbow

We get some nice low sun and rain this time of year. Which means rainbows. Almost worth taking the big camera outside and running the risk that the lens might get wet.

Almost. 

Storing Constants in Arduino Programs

Welcome to another of my "I put this into my blog because otherwise I forget how to do it and have to go onto the net and find out again" posts.....

I really like writing programs for the Arduino platform. The good news is that the devices can do a lot, but the programs themselves are actually very tiny. The bad news is that you are working in an environment where there is hardly enough of every kind of resource. Particularly memory. 

In an Arduino there are two kinds of memory. There is RAM (random access memory) which is where your program stores the variables it is working on at any given time and there is EEPROM (Electrically Erasable Programmable Read Only Memory) which is where the program code lives. When you put your program into the Arduino it is stored in the EEPROM part and runs from there. If your program creates any variables, these are stored in the much smaller RAM. 

If you want things like large look up tables (which would usually be stored in the memory of your computer) then you are heading for trouble, as you only have a strictly limited space to store data values. Fortunately you can move constant data into the program memory of the device, so that it doesn't need to be stored in the precious data space.

const byte big_lookup_table [] PROGMEM= {
      0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0 };

The statement above creates a big (actually not that big, but you get the picture) array of bytes that I've called big_lookup_table. I've added the modifier PROGMEM to tell the compiler I want the table to be located in program memory, not RAM. The table could be quite big (an Arduino UNO has around 28K of program memory available as I recall), you could save things like sound samples or images here if you wanted to. 

The only slight complication is that when you want to get hold of the elements in the array you can't just directly access them. Instead you have to use a macro which will do the fetching for you.

x = pgm_read_byte(&big_lookup_table[i]);

The statement above takes the element at location i and fetches it into byte variable x. This also means that fetching data from program memory is a tiny bit slower than "normal" variables, but in practice you don't notice the difference. 

Rob at Tech Days 2014 NL

In a few days I'll be off on my travels again. I've done sessions at TechDays in the Netherlands for as long as I can remember, and they are always great fun. Even when all the demos fail. This year I'm doing three:

• 16 April 2014
  07:45 - 09:00
  Bluetooth and NFC phone to phone communication
• 16 April 2014
  14:50 - 16:05
  Talking to hardware with Windows Phone
• 17 April 2014
  13:15 - 14:30
  Creating games for Windows 8 and Windows Phone 8 with monogame

For the hardware one I've got flashing lights and all kinds of good stuff, and I'm really looking forward to telling folks about the wonders of MonoGame. And there will be special treats for the ones who turn up at the 7:45 am session to find out all about Phone to Phone communications. If you are coming along to the conference I'd love to see you.  I've even written some new jokes..

No Mr. Bond. I expect you to fry......

Feel quite a bit better today. Well enough to watch some telly. It's Sunday afternoon, and so that means that ITV will be showing a Bond movie. And they are. "The Spy Who Loved Me". One of the worst ones in my opinion. But at the very end I saw something that piqued my interest. The last part of the credits was given over to mentions of people the producers wished to thank. This is the list of sponsors who have given money for product placement. All the usual suspects were there, Lotus cars, Seiko watches, etc etc. And right at the end: "North Thames Gas Board". 

North Thames Gas Board? What on earth did they do? Perhaps they were mentioned in early drafts of the script:

Scene 67: James Bond's apartment. James and an exotic Russian spy are having a candle-lit dinner. The exotic spy (her name is not important) looks up from her caviar vol-aux-vents and speaks:

Exotic Spy: 'James?'
Bond: 'Yes, my darling?'
Exotic Spy: 'This food, it is so delicious. Did you cook it yourself?'
Bond: 'Yes, my darling.'
Exotic Spy: 'And tell me,  what is your secret to achieving such fantastic flavours?'
Bond: 'Well, er, actually, its all about the gas that you use......'

Scene 210: Evil lair. Bond and the exotic spy (her name is still not important) are tied together on the end of a long rope which is hung over an enormous, fiery pit. The evil villain (his name is not important either) addresses them from a control room full of shiny sponsored machinery and expendables in brightly coloured boiler suits:

Bond: 'You won't get me to talk you know.'
Evil villain: 'I think I will. You see that fiery pit below you...'
Bond: 'What of it?'
Evil villain: 'Do you want to know what kind of gas I'm using.......'

Real Man Flu

Well, that's it. I'm properly ill. I feel like I've been savagely beaten by experts. And not in a good way. I spent half of the day lying in bed feeling sorry for myself and the rest of the day pottering around the place.

Feeling sorry for myself. 

Falling Ill

I think I'm coming down with something. It took me 30 minutes to change a brake light bulb on the car, and 20 minutes of that time was finding the socket spanner that I'd dropped into the toolbox to make it easier to carry.

C4DI Hardware Meetup - With Nerf Guns

Lots of Industry

Tonight was our second hardware meetup at C4DI. I knew that things were going to go well when I arrived to find everyone had already set up and was building stuff and making it do things without us needing to do anything. Peter was in charge of the exercise tonight (you can find his lab here) and he had made really good use of the flex sensor in the SparkFun Redboard Kit to create a shooting game that you can play with Nerf guns. Which he had thoughtfully provided too....

Everyone had great fun building up the circuit, getting the software working and playing with the result. The lab was great because it shows how you can create a fully formed solution (a shooting game where you have a few seconds to hit the target three times) based on this technology. 

No Cows were harmed in the making of this game

Peter had even provided a bunch of 3D printed parts that support the flex sensor target, and some cows (taken from milk cartons) to use as targets. 

Hull at the ICT Conference

Talking Pi

Today Mike and I took a bunch of Raspberry Pi systems to a teachers conference for the day. Great fun. Particularly if, like me, you contrive to arrive just after all the machines have been carried in and set up. Actually we have got this off to a bit of an art now. We have a kind of Pi road show which consists of a bunch of Ikea bags containing the monitors (the heavy bits) and a couple of boxes with all the other parts that we need to run the systems. Anyhoo, we set up shop and then talked Scratch, Python, Hardware and the philosophy of education and the role of teaching programming.

Then we packed it all back into Mike's car boot and left.

If you want to find out what we were talking about, and get notification of any new courses that we are running in the future you can sign up for our newsletter at: http://www.wrestlingwithpython.com/

Careers and Networking Event Fun and Games

Warning: This picture contains images of some students in suits...

We had our first ever Student Careers and Internships Networking Event today. I don't think it will be our last one. Before today I was only really worried about three things: No employers would turn up, no students would turn up or nobody would enjoy the event. Turned out that things went really well on all fronts though. We had plenty of folks and they all seemed to have fun. 

The audience makes ready for the start..

We started with presentations from six companies based in the area. I think the students who had come along were extremely surprised and impressed by just how much goes on around here. And the employers seemed to be very impressed by our students. Which was nice too.

Of course I took some pictures..

Get your business cards and delegate packs here

Swag

Busy

I ran a tiny "Mug Survey" at the end (fill in a little evaluation questionnaire and swap it for a departmental mug) and the results were very positive. And everyone thought we should run the event again next year. So we will. And one of my worries for next time will probably be "Is the venue big enough...."

April Fooling

I didn't have time to set up any April Foolage this year. The best one I ever did was this one, which I did three years ago. Blimey, how time flies. Great fun. Maybe next year...

All set for the Careers and Internships Event

Well, I've sent off the business cards to the printers. We've got a whole bunch of mugs on order and employers lined up to exhibit. Now we just have to hope that it all goes well on the day.  The fun starts on Wednesday at 12:30 or so. You can still come along if you haven't registered.

Properly Lazy Sunday

Spent a lot of time today not doing much. And really enjoyed not doing it.

Skipping

Spent a big chunk of the day in the garage. In the "Good Old Days" (tm) a garage was somewhere you kept the car. Nowadays it seems to be the place where you keep the family collection of empty cardboard boxes,bits of wood that at one time you thought you might have a use for and things that the kids once played with.

Anyhoo, I've filled the skip with stuff and covered myself with dust and nostalgia. Next stop, the loft.......

Of Garbage Man and Banjos

This year the first year students can create a game as part of their programming coursework. The game is "Alien Banjo Attack" and above you can see a screenshot of my demo version. At the top are various different types of evil banjo and your mission is to defend the earth using nothing more than your accordion which will shoot notes of music to destroy the incoming swarm.  If the banjos reach the bottom of the screen you lose the game. If you crash into a banjo you lose a life. Space Invaders with a banjo feel. What's not to love?

I want there to be loads of objects (notes, banjos etc) on the screen at the same time, which means a lot of instances of the various classes that represent the game objects. There has been some discussion about the best way to handle this, as banjos are destroyed and new ones appear.

I reckon the best way to do this is to make a banjo stateful. The banjo will contain a flag to represent whether or not it is involved in the game. If a banjo is destroyed this flag set to indicate that it is dead and the banjo plays no further part in the gameplay. When we need a new banjo we just have to find one which is marked as dead and "resurrect" it by moving the banjo to a new position and then changing the flag to bring it back to life. 

You might think that creating new instances of banjos to replace discarded ones would be another way to achieve this behaviour but I don't like that at all. If we start creating and destroying objects this will make work for the Garbage Collector who will have to come in and tidy up memory every now and then which might slow things down a bit. 

Another way to reuse objects would be to keep a list of "dead" banjos. Each time a banjo is killed we move it out of the "active" list into the list of dead ones. That way, if we need a new banjo we just have to look in the list. This is a bit more complicated than just searching for a banjo that can be resurrected, but it does have the advantage that the game never wastes time working through "dead" display objects, as these are no longer in the active list.  Many operating systems use this technique in what is called a "thread pool" where previously used threads are kept ready for use by processes that might need them.