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Stewart's Blog

Monkeys, megabytes, medical and more ...

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

Halloween Scary Pi-Ano – Raspberry Pi and Makey Makey keyboard

October 31st, 2014

This Halloween I created an indoor halloween light effect using a Raspberry Pi and a PIR sensor. Unlike previous years my children weren’t really involved in making this one, which is because my 9 year old daughter decided to create her own Raspberry Pi based Halloween Project.

Raspberry Pi and Makey Makey Pi-ano

She has created a Raspberry Pi, Makey Makey Pi-ano. It’s a musical keyboard using conductive play-doh shaped into pumpkins and ghosts using a biscuit cutter. The Makey Makey converts the touch contact into a key-press which is passed to the Raspberry pi.

In scratch these key presses are detected and used to play a short sound and light up a LED pumpkin using Scratch GPIO. More details on using Scratch GPIO in presentation mode on the Raspberry Pi.

Take a quick look at the video below (sorry no sound due to the speaker used being very quiet compared to the noise of the Halloween Party we were having in the background).

The LED pumpkin lights are from a shop bought Halloween decoration which I broke apart and soldered on solid core cables to make it easy to plug them into a breadboard. They were then connected to the relevant GPIO ports through a 220 ohm resistor.

I helped with the electronics and setting up the Scratch GPIO communications, but the rest of the programming is all my daughters own work.

The screen uses the HDMIPi screen, which is ideal for this kind of project.

You can download the software
Don’t forget to install Scratch GPIO extensions first.

It’s good to keep my daughter interested in programming. She doesn’t do as much as she did when she was in the Code Club I was running, but she does still enjoy it when we find a project she is interested in. My daughter also edited the video herself using kdenlive running on Linux.

Also see last years Halloween Trick or Treat scarer using the Raspberry Pi

Safely controlling mains electricity using the Raspberry Pi and Energenie Pi-mote

October 26th, 2014

It’s useful to be able to turn mains electricity on using a computer program. Whilst it’s not hard to create an electronic circuit that can switch mains voltages, if not done correctly it can be dangerous. This is where the remote control sockets can be used to create a physical barrier between the low voltage electronic circuit and the dangerous high voltage electricity in the socket. Whilst it would be possible to create a radio transmitter to control the sockets yourself I wanted to keep this simple so that it is something that could be made easily by anyone. In an earlier project Home Automation using the Raspberry Pi I opened up a remote control and used relays to emulate a button press.

Energenie Raspberry Pi remote control board (Pi-mote)

Since I created the circuit by hard-wiring across the buttons on a remote control, Energenie has created a Raspberry Pi add-on board which allows one to switch power sockets on and off using the Raspberry Pi. The board is plugged into the GPIO port of the Raspberry Pi making it easy to send messages using software.

Energenie remote control power socket

There are a few limitations to this Energenie product compared to the Bryon home automation product I had used previously. When I bought the remote control sockets I also bought a traditional remote control hoping that I would be able to use both against the same socket. This is something I did with the Bryon system where a socket was timed to come on at a certain time, but where I could use the standard remote control to override that. In the case of the Energenie product it works with the Energenie Pi board or the remote control, but not both at the same time which I was surprised by. It is possible to overcome this by only using the Pi board and relying on software and a virtual remote control (eg. on a mobile phone). Another limitation is that the only products available are sockets or a power strip, whereas with the Bryon remotes I was able to turn a light on and off as well. The main advantage is that this plugs on to the Raspberry Pi and is very easy to use whereas my earlier project was a little temperamental due to soldering onto tracks in a way that the product is not designed for.

One thing about the Energenie remote controls is that I believe they all the remote controls (including the pi-mote) are registered using a unique code. Whilst this prevents having multiple controllers for each socket it does have the advantage that a neighbour using the same system cannot accidentally interfere with your sockets. I don’t believe it adds true security as it would still be possible to create your own controller board that monitors the wireless signal and then sends the same signals it does protect against accidental triggering.

I think that the Energenie product is better for most purposes, but it would be great if dual remote could be added in future as well as some other home automation adapters.

Adding an aerial

One thing I did do to the Energenie Raspberry Pi board was to add an aerial. Without the aerial the most it could work over was about 2 meters which is not particularly useful. Soldering a 135mm long piece of wire to the board extended the range considerably.

Energenie Raspberry Pi power remote board with aerial

Energenie Software

The instructions for the Engergenie include some example python code. The code is however it is not particularly easy to use. Instead I used the Pi-remote code python module written by Amy Mather (whilst on work experience with Raspberry Pi foundation). This code makes it easy to program the Energenie Pi-mote board.

The power control web interface

The web interface uses the module mentioned above and the Python bottle web framework. The bottle web framework is a simple way to create a web application with a built in web server rather than needing a separate web server such as Apache.

The software can be downloaded using


or: Download pi-power.tar.gz and copy it to the Raspberry Pi home directory.

Unzip the file using

tar -xvzf pi-power.tar.gz

change to the pi-power directory cd pi-power and then run the software using:


This will start the web interface and you can then connect to interface using the IP address of the Raspberry Pi in a web browser. It should be possible to connect from a Raspberry Pi, PC or mobile phone and click the appropriate button to turn the socket on and off.

You do need to register the socket with the controller (it not already done using the Energenie demo code). This may vary with different sockets, but the model I use involved starting with the socket in the off position (press green button until the LED is off) then holding down the green on/off button for a few seconds (until the LED starts flashing) and then using the on button on the remote.

Energenie Raspberry Pi remote on HDMI Pi

The code is dependant upon Ajax, so a fairly recent browser is needed with Javascript enabled.

No security

Please note that there is no security included in the software provided. This means that anyone on the local network (eg. your home wireless network) can turn the sockets on and off.

It’s also possible to say that by virtue of the remote being wireless it wouldn’t be too difficult for someone to capture the wireless remote control signal and create their own remote control that sends the same signal to turn it on and off.

I would however recommend adding some form of user authentication if you intend to make the remote control accessible over an insecure network (eg. the internet).

Project ideas

As the pi-mote is controlled from the Raspberry Pi it would be possible to add other triggers to switch the sockets on and off. Using other software it would for instance be possible to use sound/voice activation (using an additional microphone) or with additional hardware based on the temperature of the air or of a liquid.

Whilst the pi-mote add-on board does not use all the pins of the GPIO port it does not make it easy to connect any other devices onto the GPIO board.


Using Engergenie sockets with the pi-mote Raspberry Pi add-on board makes it safe and easy to create a project that switch mains powered devices on and off. It does have some limitations including the restriction of only 1 board controlling the socket and not being able to access the available GPIO ports, but the simplicity of connecting this to the Raspberry Pi is a big plus.

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.

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