The MagPi: back from Digimakers, saw something LAZEY

On Saturday I travelled over to Bristol with The MagPi stand featuring George the robot arm (all of my robots are called George. I blame this), a mountain of sweets, HDMIPi and a Saleae logic analyser. Yes, that’s quite a varied collection of kit!


The event was absolutely fantastic, with robots everywhere (as you’d hope). One stand had several other Maplin Robot Arms (so George didn’t feel lonely) and was teaching the basics of robot control. LEGO(R) Mindstorms were in abundance and it was great to see programming at various levels (proof positive that the Mindstorm is a pretty decent bit of kit - I’ve spent a lot of time with Mindstorms v2. Even the basic drag-and-drop programming GUI supports up to 32 threads!) One group of kids had a very well thought out Mars exploration challenge setup (this one, I think), programming their Mindstorms v3 rover to overcome all sorts. I chatted with them about threaded programming (Did I mention? 32 threads! Awesome!) and it was really encouraging that they got what I was on about (even though my explanation wasn’t the best - sorry guys, I was running on coffee and two hours sleep from the previous night!) Raspberry Pi Spy has a great photo of the team in action.

I managed to spend a reasonable bit of time showing people how to use the Saleae logic analyser, and talking about how, before I used one, I’d managed to get myself in a right kerfuffle not knowing what was going on with an excellent 3IR line sensor I’d bought from Ryanteck.

Getting HDMIPi working was great. I’d had a bit of an issue with a dodgy USB connector, but Alex Eames of had sorted this for me just in time. Thank Alex! You’ll be pleased to know that HDMIPi garnered a lot of interest with many a “hey, that’s neat” comment. Here it is with Sintel running, a great (albeit very sad) video from the Blender people.


One of the most impressive displays present was the LAZEY Projector, a laser persistence of vision generator by Adam and Joshua, students at Bristol Uni. Roughly speaking you draw an image on a tablet which is sent wirelessly to a Raspberry Pi, which renders the image and sends it to a custom shield that plugs into the Pi, which buffers and then sends commands to a couple of mirrors that reflect the laser light in such a way as to draw the image on screen. Absolutely brilliant. You can see from the photo below that my smartphone’s camera can’t capture the whole image as it is being redrawn many times a second - too fast for us lowly humans to notice, but a camera easily captures it mid-render.


Here’s a video of what LAZEY can do. Sweet.

Oh, and it also plays tetris.

Unfortunately I didn’t get a photo of the LAZEY unit but over at Raspberry Pi Spy you can see it up close.

Another stand had a Sudoku solving machine / robot running. This was a neat bit of kit as it would draw a 6x6 grid with a black pen on a whiteboard, then place some initial numbers. You played by trying to solve each square and it would light green for a correct answer or red for an incorrect one. Apparently it was all built in under 24 hours as part of a competition they had previously entered: they could take along all of the parts, but nothing could be pre-assembled. Kudos guys, it was really neat.

There was also a fair bit of interest in the competition that we were jointly running with the organisers. If you need details get in touch via their FB page. Bristol Uni are doing the judging. Good luck to all who enter!

So, with workshops, demonstrations and robots giving out sweets who could ask for more. I had a fantastic day. Hope you did too if you went. If not, the next Digimakers is on 29th November at AT-Bristol in Bristol.

The MagPi at Bristol Digimakers - with competition prizes

The MagPi has agreed to co-sponsor the competition Bristol Digimakers on the 4th October at the At-Bristol Centre in Bristol. We’re offering up a bundle each of Volumes 1 and 2 of the magazine. Plus one of the organisers, Caroline Higgins from University of Bristol has managed to secure the famous Blue Pi as a prize as well. These colourful Pi’s are like blue-coated gold dust they’re so rare.

I’ll be running The MagPi stand at the event, which is an absolutely top-notch event for people in the South West who find the events in Cambridge and Manchester a might too far to travel. With technology demonstrates from the University of Bristol, local companies and several individuals (no doubt with robots: there are always robots, and robots are a Good Thing) plus a ton of workshops to get your brains around Scratch, Python and various hardware challenges (usually with LEGO(R) Mindstorms, Raspberry Pis and LEDs galore) it’s a fantastic opportunity to meet up with people, brush up on your skills and learn new things.

The event is primarily aimed at kids of all ages, but there are also plenty of teachers, parents and people interested in technology who come along too. The event has a great vibe, with a real buzz around technology. Great stuff.

So what’s going to be going on at The MagPi stand? Well we’re going to have a bundle of hardware goodies for you to see and play with:

  • The new HDMIPi LCD for the Raspberry Pi
  • Traffic lights with PiStop from Tim Cox
  • Using a Slice of Pi/O to control a 3 Line Follower Sensor from Ryanteck. The Slice of Pi/O is a great base upon which to connect various robot sensors and I’ll be showing you how to use this piece of tasty kit.
  • Using a Saleae Loic Analyzer with the Raspberry Pi (using it to show the importance of pull up and pull down)
And yes, the robot arm will be back dishing out sweets to all those that can master the fiddly controls.

Plus a ton of Raspberry Pi books for you to browse to get ideas for that next purchase.

A collection of event links:

digimakers014 digimakers013 digimakers012 digimakers011
A few photos from previous MagPi and other stands at Digimakers (yes those are musical bananas)

HDMIPi: top notch customer support

Alex Eames is a star. My HDMIPi unfortunately broke when the USB connector snapped off of the driver board with nary a hint of pressure. Turns out there’d been a problem with manufacturer that Alex and co had only just become aware of. They’re fixing every board going out (so yours likely won’t have this issue) but I was fortunate (!) enough to receive one sent out quickly, i.e.: before problem was unearthed.

Total turnaround from reporting the issue to receiving a replacement driver board was well under 48 hours. Superb. This is the kind of customer service that engenders a true sense of loyalty to a product and brand. It’s one of the reasons why I’m a huge Amazon fan. Just as with Alex, whenever something I’ve purchased from Amazon fails they get a fix to me pronto without any quibbles. I’ll *always* support companies who provide such excellent support.

Broken HDMIPi
A sad HDMIPi-day.

HDMIPi is happy again (and yes that’s an Apple wireless keyboard attached. More in a future post)

HDMPI arrives: assembly and first impressions

By chance I was actually in when the postman knocked on my door and gave me a plain brown cardboard box. Inside was HDMIPi in full kit-to-be-assembled form. This caught me surprise as I thought HDMIPi was still at the assembly stage (clearly I need to read my emails more closely). Great stuff: a new kit to play with :)


The whole package is pleasingly arranged in the box, with the several layers of case surrounding the screen, which came in bubble wrap to protect it. A nice thought. Anyway, that’s enough of unboxing *yawn*. Let’s play with the thing.


There is a great video from along with instructions on the HDMIPi website. The video really is step by step and you really can follow it along. Alex Eames has done a great job of explaining exactly which way around all the case components go. Have a dust cloth and a little rocket blower like the Giottos GTCL2810 Q.Ball Angle-Adjustable Air Blower handy to keep dust off. I managed to get two annoying dust spots on the screen before assembly, but in the scheme of things that’s a “meh” and I probably won’t worry about them.

My only two niggles are:

  1. The two 12mm x 2.5mm screws looked identical to the 12mm x 3mm screws at first. So much so that I’d put them into the edge holes on the case and had to go fish them out again. Mental note: always count your screws before building anything.
  2. The USB - micro USB cable that connects the driver board to the Pi is a tight squeeze. It has a double-U (a bit “W”-like I guess) curve that meant it didn’t want to sit parallel in either socket until I applied a fair bit of “bend-thine-cable” force to the cable itself. Now though seems fine and I guess we’ll see soon if it pops out. IMHO a flat mini noodle-like cable would have been better here and this is something I’ll likely take a look at in the future if this proves an issue. You can see the cable in the photo below.

The driver board is held securely next to the Pi and there’s no problem in assembling it all. After assembly there is definitely space for a slimline battery in there.

To be honest the driver board is a thing of beauty, it really is. It’s darn compact and given it supports a second HDMI output (unfortunately not dual-monitor) it means you can plug your Pi into the widescreen TV in your lounge without having to dismantle the enclosure. Nice.

First boot

The Pi booted first time and the screen lit up without a hitch. I was slightly surprised to see it claiming full HD 1920x1080 when the advertised specs were for 1280x800. However I think (not confirmed) that the higher resolution is scaled. In either case it certainly looked cramped on screen. I followed the instructions to change this to 1280x800 and the whole package became immediately more usable.

How’s it handle

It’s a fairly solid surround, as you’d expect from Pimoroni. A gripe here is that the driver board is only about half an inch from the case and without too much difficulty things could possibly fall in and short. But that’s a hypothetical risk, not something I’ve had a problem with. Your fingers are unlikely to find themselves inside.

One thing I would love (love I tells ya!) would be a rubber bumper surround for the whole thing. I’m going to suggest this to Alex.


The ethernet and USB ports have a cut away at the case which you may need to remove. I made the mistake of plugging in an ethernet cable without removing this plate: try unclipping an RJ45 ethernet connector with anything less than a it-conducts-electricity screwdriver and you’ll see what I mean. This won’t be a problem if you remove the cut edge plate first, or use a dinky WiFi dongle (as I now am).

I’ve been toying with buying a new wireless keyboard and trackpad combo to replace my wireless keyboard and mouse and now seems a good opportunity to do so as the adaptor sits too far out from the board, and is kinked at a nasty angle. Again, fixable with a smaller adaptor or by cutting away the small edge panel. Something to be aware of anyhow.


Something has to be said for how the driver board dishes out power to the Raspberry Pi. To give you an idea: without HDMIPi a WiFi dongle plus my wireless keyboard and mouse adaptor has always been too much for the USB ports regardless of power supply I use (Even good quality 2A ones). Either the mouse goes all jittery or the WiFi is up and down like a Yo-Yo necessitating the need of an external powered hub. However, with HDMIPi I’ve found so far that this combination is rock solid: WiFi AND a mouse at the same time! Bonza! Obviously you’re mileage will vary.

A note on GPIO: all the pins on the P1 header are available, sunk slightly (~2mm) into the case. This should protect them if you accidentally put the HDMIPi down on something conductive (and when’s that a good idea?). Would you believe it, your GPIO expansion board of choice may work. I tried PiLite and XLoBorg were fine, but TriBorg catches on the plastic case slightly. If this is an issue you can always use a ribbon cable to solve this. XLoBorg is an interesting one as it gives HDMIPi accelerometer and magnetometer capabilities, which coupled with a wireless, battery powered Pi is very, very interesting. A bit of black masking tape, or Sugru would do the trick nicely to cover up XLoBorg.




(The bump out the bottom left is my oh-so-slightly too large wireless keyboard and mouse adaptor).

There you have it, a first look at HDMIPi. My take: an absolutely top notch way of getting a portable 9” screen fastened to your Pi without sacrificing functionality (GPIO or external HDMI connections).