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Stewart's Blog

Monkeys, megabytes, medical and more ...

(Children, computing, first aid and other ramblings ...)

Going Sober for October – What is it really about?

October 15th, 2014

Go Sober

Last time I wrote about my Going Sober for October challenge it was pretty much about what I was doing, but this time it’s more about why I’m doing this and the charity that I’m raising money for.

I’d certainly heard about Macmillan Cancer Support charity and particularly about the Macmillan nurses, but I’ve not had any involvement with Macmillan before joining this campaign. I first heard about it from an advert on the radio and for some reason having a month without drink sounded like a good idea. I don’t see it so much a challenge as it is a test of will power. The reason that I decided to go ahead with the challenge is that the more I found out about Macmillan cancer support the more important I think the organisation is.

I can’t explain it as well as Macmillan does itself and so I suggest you watch this short video, or this slightly longer video on the Macmillan website which explains more about the role of the Macmillan nurses. What I can say is that I’d want Macmillan to be there for anyone I love if they were diagnosed with cancer.

So visit the website, find out more and help support by sponsoring me to keep sober until the end of the month.

Zip World velocity – the worlds fastest zip wire

October 15th, 2014

Zip World velocity is the worlds fastest zip wire and the longest in the northern hemisphere, and it’s in Wales.
The zip line goes across a former slate quarry in Snowdonia.

I visited on the same day as going White Water Rafting.

When we arrived we were weighed and height measured before we were kitted up with a one piece suit, helmet and glasses. We then had a short walk to the first zip line, the Little Zipper, which is 420 meters long and reaches speeds of up to 65km/h.
The reason for the weighing became apparent as we were given different amounts of additional wind resistance (effectively small sales) and instructions about holding our arms out at different points to slow us down before reaching the end.

We were then driven up to the top of the quarry in a truck ready for the Big Zipper which is a massive 1560 meters long and has a top speed of up to 165km/h.

The ride does feel very safe as the harnesses are checked and then cross-checked by another person before each flight.
The launch from the top platform is performed whilst laying in the harness and is released by the operators. This makes it easier for those nervous of going on the zip wire, for me it didn’t have the same adrenaline rush as zip wires where I stepped off a platform such as those at Go Ape! (obviously for safety reasons that is not an option on these zip wires).

The zip wire is very fast, but whilst the initial start feels fast once travelling across the quarry the ground is a long way off so some idea of perspective is lost. You do then realise the speed again when coming in to the end of the zip wire. Flying across on the zip wire is a great feeling and well worth doing.

You also get a free video of the ride. I’ve created an extended version by adding some additional footage from my GoPro camera (included in the video above).

Zip World in Wales

There’s just one complaint about the site and that’s the limited toilet facilities. There is one toilet inside the main building and temporary toilet with one male and one female toilet which did mean a big queue when everyone was wanting to go to the toilet before we got into the harnesses.

The ride is dependant upon the weather, but there are no refunds even if your ride is cancelled up to 24 hours in advance. Instead you would need to re-book within the next 12 months. This is OK if you live within a reasonable distance, but I could see this being an issue for anyone that was looking to do this whilst they were on holiday in Wales and didn’t have an opportunity to do it whilst on holiday, so please check the terms and conditions before booking.


This is a very long and very fast zip wire and it’s great to be able to say I’ve been on it. It is however expensive for such a short period of time on the zip wire. I’m certainly glad that I had a go, but it’s not something I’d be in a rush to do again.

Book – Mastering the Raspberry Pi

October 14th, 2014

This is the second book that I’ve been the technical book reviewer for, the first being Learn Raspberry Pi with Linux.

When I was contacted by Apress to ask if I’d do the review then I didn’t hesitate to say yes as from the description this sounded like just the sort of book I would be interested in. It did turn out to be the sort of book that I hoped it would be.

About Mastering the Raspberry Pi

Mastering the Raspberry Pi is a book that delves into the inner working of the Raspberry Pi and combines electronics and programming using the Raspberry Pi GPIO port. The projects mainly use inexpensive electronics modules or components and provides the code required to get them working. To give a few examples it includes a real time clock add-on which ensures that the Raspberry Pi can keep time without needing a network connection, a Wii Nunchuck controller which provides an alternative controller to using a mouse and details of how to use the GPIO ports to control devices such as stepper motors.

It has got quite a bit of theory, but also uses fun and interesting projects to make this a practical book as well as a useful reference.

Target audience – not beginners

Mastering the Raspberry Pi book
It’s important to know that unlike many of the other books for the Raspberry Pi this is not a beginners guide for those new to programming. This is not designed for children, although would be suitable for those studying computer science at further / higher education or for someone that has already gained a good understanding of programming.

You don’t need much experience with electronics as it mainly uses pre-built modules or very simple circuits, but some programming experience is essential and preferably some experience in programming in C. This would be a good book for someone that already has experience with higher level programming that wants to learn more about how drivers are written and how to get down to the raw code that communicates with peripherals.

It won’t go as far as teaching you to be a kernel hacker, although it does provide information on cross-compiling your own kernel and it’s certainly a step in the right direction if that is something that interests you.

It also provides a good technical reference to the working of the Raspberry Pi, it’s built in hardware and the GPIO ports. Whilst most of that information is already available from public sources it would take a lot of research to find out the information contained in the book. This can therefore be a big time saver.

Model A and B vs model B+

The one negative comment I have about the book is that it is aimed at the Model A and Model B Raspberry Pi, but there is now a model B+. This is not the fault of the author at all, as the book was just being published as the B+ was announced. The programming doesn’t change much except for the availability of more ports, but it does mean that there are some ports on the B+ that would need to be researched by the user. This is only going to be an issue for a few users and it still gives the basic information that is needed when researching the additional ports, so after following this book you should know enough to find the rest yourself.


This is not a book for complete beginners, but if you’ve already done a bit of programming and want to go to the next level then could be a good fit. It’s also going to be useful for someone working with electronics hardware for the GPIO that wants to program directly with the GPIO rather than using the standard libraries.

A more detailed description (and option to buy as eBook or physical book) is provided on the Apress website – Mastering the Raspberry Pi

Whitewater rafting at National Whitewater Centre Wales

October 12th, 2014

I have done a lot of kayaking in the past, but until recently I’d never tried whitewater rafting.

We went to the National Whitewater Centre in Wales. The centre is Canolfan Tryweryn on the Upper Tryweryn river near Bala in Wales. After getting changed into a wetsuit, buoyancy aid and helmet we had a short training session / safety briefing on dry land. We then loaded into a mini-bus which drove us to the get in point.

We had a quick recap of the instructions on the river before we reached the rapids. We then followed the instructions from our instructor which involved paddling, holding on and “getting down”, which kept us safely in the raft. We did however get very wet with a complete soaking through one of the falls and paddling back into the stopper to give those in front an extra drenching.

White water rafting at the National Whitewater Centre

We ran the river four times in total each of which involved something different (going backwards / extra drenching / even faster). By the end we were exhausted, but it was a great fun.

I had my own Go Pro camera which I’ve used to put together the video below. It’s worth remembering that the GoPro was attached to the top of my helmet, so if the water looks like it’s getting close to the camera then it was already over all our heads.

English Heritage – Brodsworth at War

October 10th, 2014

I had already visited Brodsworth Hall and gardens taking my children for a day out on a standard day. This was our second visit which was on one of the Brodsworth at War special event days. I took my family along as a member of the English Heritage members panel.

Brodsworth Hall and Gardens - Brodsworth at War special event

The day that we visited was based around the end of the war, preparations for the returning troops and plans for a memorial for the fallen.

I visited with my family including our two children Amelia aged 9 and Oliver aged 4. We arrived during the morning. The gardens were open, but the hall didn’t open until 1pm. That was not a problem as it gave our children time to stretch their legs after the long drive, so we went straight to the children’s play area. The play area includes an old boat, two play boats and a good climbing play area with climbing wall and rope ladders. Unfortunately the old boat was fenced off to allow for repairs, but the rest of the play area was in excellent condition.

Brodsworth Hall children play area

We then had lunch from the tea room, which we ate outside before going into the hall.

We have visited Brodsworth Hall before when the normal theme in the hall is about the history of the Hall and the families that lived there. During the event there was still regular features about the family, but many of the rooms had special features relating to the hall being requisitioned for use as a headquarters for the home guard. Whilst we certainly enjoyed looking around the hall before, this special event was better than the previous visit as the World Wars are something that our children had learned about in school. There was some quiz sheets that the children could fill in as they went around the hall. The quiz was particularly well written as it made it obvious which room the answers could be found it. This avoids the frustration of having to backtrack if you miss a clue. They also made the use of interactive audio exhibits in many of the rooms.

My children also enjoyed learning French knitting thanks to some of the English Heritage volunteers.

Brodsworth at war - Croquet on the lawn

After exploring the hall we played some croquet on the lawn and then explored the large gardens. There was plenty to explore in the gardens including a summer house, a target house and various paths and bridges.

Brodsworth at war - visiting the gardens

There were also several themed activities throughout the day, including music and some theatrical events. These were less appealing to my children, but I enjoyed the one that I watched. The one that I watched involved the vicar and the lady of the house talking about a memorial for those that died during the wall. The acting was really good and it provided a different perspective to the displays in the hall.

Brodsworth at War - discussing the war memorial

Go Sober for October – raising money for Macmillan cancer support

October 9th, 2014

Go Sober
For the month of October I’m giving up drinking alcohol as part of the Macmillan Go Sober for October campaign.

It’s been a week now and it’s going well. I don’t normally drink too much, but I do enjoy drinks especially with certain meals or when going out. I’ve therefore been swapping my drinks for a similar non-alcoholic drink instead. So instead of wine I’ve been drinking flavoured sparkling water or Appletiser and instead of a beer I’ve been drinking a non alcoholic shandy. I’ve also treated myself to a few other non-alcoholic drinks that I wouldn’t normally buy.

As well as helping raise money for a worth cause I’m hoping this will be a more healthy month. I’ve lost a couple of pounds this week through not drinking and eating less and hopefully I should have lost a few more by the end of the month. Whilst I do plan to start drinking again next month I may drink a little less than I did before.

Non alcoholic drinks for Go Sober for October

The most important part of the Go Sober campaign is to raise funds for Macmillan cancer support. A quick look at my campaign page and I’ve not raised quite as much as I’d hoped so far. I do however have some offline donations which won’t be counted until they get paid in at the end of the month. There is still plenty of time for people to donate, so please help support this important cause and help keep the incentive for me to keep off the drink by clicking on the link below.

Thanks for the donations!

Malvern Festival of Innovation school’s day

October 3rd, 2014

It’s not often that you see a Raspberry Pi workshop, a team from (soon to be???) the worlds fastest car and some llamas in the same room, but that’s what you’d find at this years school’s day at the Malvern Festival of Innovation.

Malvern Festival of Innovation - Raspberry Pi, Llamas, Bloodhound SSC and The Little Pi shop

I was there as a STEM Ambassador helping out on the Raspberry Pi workshops. These were run by the IET, The Little Pi Shop and volunteer STEM Ambassadors from Hereford and Worcestershire. Gordon Hollingworth from the Raspberry Pi Foundation also made an appearance.

During the day we had 6 schools (nearly 100 pupils I think) who had a go at building a simple electronic circuit and writing a game in python. This is similar to something I’d done (on a much smaller scale) with a local high school (Python and the Raspberry Pi GPIO), although this one had less time so involved a bit less coding.

Most of the pupils that attended had never done any Python programming before, but they seamed to enjoy the activity and managed to create their own game. It was a great day and I enjoyed helping the pupils learning programming.

Family day

This day was for schools only, but there is also a family day which is open to the public on Saturday. It’s organised differently from the school day, but sounds like it’s a good day out. See the link below for more information.

STEM Ambassadors

STEM Ambassadors are volunteers that work using or are interested in the STEM subjects (Science, Technology, Engineering and Maths). It’s an opportunity to pass on your enthusiasm and knowledge to children encouraging them to take an interest in STEM. There are lots of opportunities to volunteer with events such as this and a CodeClub I run in a primary school, or helping to support teachers rather than working directly with the children.

Find out more below:

Kids education day at PyconUK 2014

September 24th, 2014

PyCon UK is the UK conference for the Python programming language, held annually at Coventry. PyconUK is attended by many professional developers, but has recently added an education day to the line up. Last year was the first day that kids were specifically invited through the PyCon UK Raspberry Jam. For 2014 this evolved into the PyCon UK Education Track a two day event running concurrently with the main conference. The first day (Friday) was for teachers and the second day (Saturday) was for children. The kids day cost only £5 per child (accompanying parents free) which was excellent value for money considering it included lunch and a goodie bag.

I attended with my two children, Amelia (9 years old) and Oliver (6 years old). My daughter had also attended the previous year, but this was my son’s first time.

PyconUK education day - kids learning programming

Minecraft Pi

The day started at 9.30. After a welcome to the event Martin O’Hanlon (one of the authors of Adventures in Minecraft) gave a presentation on programming for the Raspberry Pi Minecraft API. His presentation had an instant impact on the children who were clearly impressed by the ability to build a city of houses or having a house that follows behind and of course the canon to blow up his windmill.

The children were then provided with a worksheet on programming the Minecraft API. This started with a simple message on the screen and build up to an automatic bridge that would appear wherever Steve walked. Whilst Oliver has been working through the Code Club Scratch programming (he’s my guinea pig for preparing for the code club I’m running at the moment) this is the first time he’s seen Python. He didn’t like the typing involved, although that’s understandable considering he’s quite young, but enjoyed the testing part. Amelia did most of the actual typing and together they to work through the exercise finishing just in time for the next session.

Second session options

For the next session we had a choice of different activities. Initially I was thinking of taking Oliver along to the lego robot session (he’s a big lego fan), whilst Amelia went to the Stop Motion session run by the Raspberry Pi education team. Due to technical problems the lego robot session was not running as planned (although I believe some of the kids still managed to get some lego robot stuff working), so both my children went up to the Stop Motion camera. Amelia had gone ahead already and had made friends with another girl, so they partnered up. I could therefore work one-to-one with Oliver.

There were also sessions on PyGame (for the older children) and programming Quad-copters.

Push Button Stop Motion with a Raspberry Pi

The Raspberry Pi education team ran the second session that we had. This included Carrie Ann Philbin (author of Adventures in Raspberry Pi), Ben Nutall (author of much of the Raspberry Pi website documentation) and Alex Bradbury (one of the authors of Learning Python with Raspberry Pi) talked us through the steps involved in creating a push button stop motion camera. This involved wiring up a button to the GPIO and adding some Python code using the picamera module.

Full details are available on the following Raspberry Pi resource: Push button stop motion guide on the Raspberry Pi website

Raspberry Pi at PyconUK

The trickiest part of the setup was how to mount the camera so that it didn’t move around. We used a PyCon UK rubber duck to create our own “Duck Cam”.

Oliver didn’t want to do any typing, but other than entering the code this was very much a hands-on and do activity which he responded to really well. We were able to get up and running quite quickly and in no time had our first animation using some lego figures. We then had a play with some jelly beans which danced around the table before mysteriously disappearing (I’m not sure where, but they were very yummy).

We finished with a funny face video.

During this Amelia was being helped along with a volunteer. I think he may have been one of the teachers from the previous education day that had come to help out. It took them longer with the girls doing the typing, but they managed to create their own video by the end of the session.

Lunch with robots

It was then time for lunch with a demonstration of some robots. These robots were well out of the budget for most homes and schools, which is a really shame as they were very cool!

Hopefully in future they will come down to a more reasonable price, but until then this was a rare chance to see them in action.

Robot at PyconUK

Open session – back to the Raspberry Pi

The afternoon was an opportunity to carry on with one of the previous activities or to have a go at something else. My children teamed up together to work on another stop motion video.

This started with them trying to find as many Simpson / Lego movie figures from the Raspberry Pi’s Lego box and then making up a short story. The story involves a Lego spaceman and Lisa Simpson building a wall, that is promptly destroyed by a girl robot, who is chased away by Chief Wiggum on a motorbike. Wyldstyle then comes in and with a bit of Master Builder know-how rearranges the Lego, which turns into a real life Raspberry Pi, which the Simpson cast all come to look at. Awesome!

You can see the video below:

As well as the programming aspect to this, it’s a great example of how computers, especially the Raspberry Pi, can be used for other creative projects. A great way to combine art and computing.

The end of the day

At the end there was an opportunity for some of the children to show off their work.
The event was well turned out and many of them wanted to show off their work. Unfortunately there was not enough time for everyone, but there were some great demonstrations.
This included several Minecraft demonstrations (such as a “Tardis” style building that was bigger inside than outside), some PyGame mazes and some of the videos from the earlier stop motion session. Oliver’s funny face video was one of those shown which raised a few laughs!

As well as all the fun of day the children all took home a bag of goodies to help encourage them to learn programming at home. This included a Raspberry Pi (the latest model B+ no less) and a copy of the book Getting started with Raspberry Pi, a debugging duck and some Pycon swag. This means that the children can go home and carry on the programming they started and hopefully encourage them to pursue it further. We returned one of the books as there were not quite enough for all the kids and my kids were happy to share, but they did get their own Raspberry Pi to encourage them to create their own projects.

A great day that all the kids enjoyed.

Thanks to all those that put in so much effort to make the day go so well.

HDMI Pi – 9 inch screen for the Raspberry Pi

September 22nd, 2014

The HDMI Pi screen for the Raspberry Pi has now been made and is shipping to the kickstart supporters.

It’s been a long wait, although much of that is due to changes and improvements in the design and we’ve been kept informed about the progress. So was it worth it ? …


HDMI Pi 9 inch screen for the Raspberry Pi

The final specs are that it’s a 9inch screen (1280 x 800 LCD screen) with 2 x HDMI inputs (one of which is used for the Raspberry Pi), an internal supply connector (allowing you to power the Pi and monitor from a single power supply). There is also an audio out jack (taken from the HDMI audio stream).

I’ve just received mine. I’ve assembled it and got it working, but not had time to try it out fully yet, so this is an early review. I chose a black frame, it’s not the most exciting colour they offer, but is plain to allow it to be used for different purposes.

The screen comes in kit form and takes about 30 minutes to put together, but the process is fairly straight forwarded following a YouTube video. Most of the assembly is removing the protective covering on each piece of perspex and putting them together in the correct order (anyone with a Pimoroni case is familiar with that), with a couple of cables to connect (no more difficult than connecting a Pi camera). the whole assembly feels quite sturdy, there is a little flex on the side when pressing, but only a very small amount. It does include a perspex screen so care will need to be taken to avoid scratching – so no throwing it in a bag with anything metal.

The first version comes with a plate to fit the Raspberry Pi Model-B, although a version for the B+ will be available in future.

Even with the Raspberry Pi installed it is possible to get the ports and connectors on the Raspberry Pi, including the GPIO. You may need to make some slight modification with a hacksaw if you need to connect to an analogue TV although it’s unlikely you would want to use that compared to the HDMI screen. It can be a bit tricky to get to all the ports, although you can always unscrew the back panel and then screw it back in place.

I used the two USB ports for a Wifi USB dongle and a combined keyboard and trackpad, which meant I could use the Raspberry Pi without any cables other than the power supply and it didn’t need a USB hub.

HDMI Pi 9 inch screen for the Raspberry Pi with keyboard and trackpoint

I booted the Raspberry Pi with a new NOOBS install. It worked well, but didn’t quite fill the screen. The LXDE monitor configuration tool does not recognise the screen to change the resolution, but there are details in the instructions of how to change config.txt to fix this (not done in the above photos).
The screen is quite small so at the full resolution then the text is tiny. If you have good eyesight then you should be OK, but others may want to reduce the resolution to see the text larger (you can change the font size in many applications, but unfortunately there’s no easy way to increase the text size across the desktop and all applications).

There one small thing if looking to mount the screen. The Raspberry Pi protrudes slightly from the back of the screen (particularly the USB connector), so although there are mounting holes on the back for mounting it on a wall then it may be difficult to get it flush without another perspex layer or a cutout.


This is a well designed screen that allows the Raspberry Pi to be installed to make it a nice tidy module with only one power lead. This is much better than the cabling spaghetti I had before. It is much better than I first thought from the initial Kickstarter and is good value for money. I’d highly recommend one, although you may want to wait for the next version …

Future version

The latest announcement is that there will be a 10 inch version in future with the possibility of it being touch screen. If you need a screen fairly soon (they will still take a while to ship) then I do recommend the current version, but the possibility of touch means it may be worth waiting for the 10 inch version.

More information

For full details visit:

Adding thumbnail images to MP3 tags for Citroen C4 Picasso USB MP3 player

September 16th, 2014

I have recently got a new car with a full graphical entertainment system. It’s a new Citroen C4 Grand Picasso with a built in Touch Drive system which includes a USB MP3 player. The system includes a 7″ touch screen which can display MP3 thumbnails.

Citroen C4 Picasso USB MP3 files with thumbnail images

My CD collection is already digitized and includes JPEG cover images for many of the CDs. I copied the files to a USB drive and inserted it into the car. The files played fine (or at least the first 18GB or so of files as there appears to be a limit to the number of albums that can be loaded), but only a small number of thumbnail images were shown.

After some investigation I found that it only shows thumbnails for mp3 files where the image is embedded within the MP3 Tags. The next challenge was to find a way to easily update the MP3 tags across thousands of MP3 files without having to manually edit each one. I found two programs, which are both open source and are available for Linux (as well as other operating systems such as Windows). I tested this on Ubuntu Linux 14.04 and can be found in the Ubuntu software store.

MusicBrainz Picard

The first is MusicBrainz Picard, which was able to lookup the audio files automatically and in many cases add the images directly. It wasn’t successful with all my audio files, but was able to get a lot of the files updated which vastly reduced the number that I had to manually add.

MusicBrainz Picard - add images to MP3 tags on Linux and Windows


EasyTag is more of a manual tool, but allowed me to go through the files that were not recognized by MusicBrainz Picard (which was still a significant number) and manually add a thumbnail image into the MP3 files.

EasyTag - adding thumbnail images to MP3 tags

Thumbnails images working on MP3 files

After adding the thumbnails then the cover images are now shown on my car MP3 player. It also has the advantage that lots of other software also recognises the images. This includes XBMC and other media PC solutions. So whereas before I had to create different thumbnails for different players, or I had to edit them manually in the software most players can read the MP3 tags.

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