Sunday, January 27, 2013

Egham Raspberry Jam report for Sunday 20th January

Having caught Raspberry Pi fever and attending the excellent Milton Keynes Raspberry Jam on a couple of occasions I approached my employer about running a Raspberry Jam at our offices in Egham. After a bit of explaining what a Raspberry Pi is and what a Raspberry Jam is they gave the green light and we put the 20th of January in the calendar as the date for the Raspberry Jam.

Eventbrite page was set up to allow registration to keep the numbers to a reasonable level and started to promote the event on the Raspberry Pi forum and on Twitter through my @Winkleink account. Through retweets from @Raspberry_Pi and @Teknoteacher we got 50 registrations with over a week to go.

I put out the call for presenters and two people stepped forward
Dave Ackerman the Pi in the Sky man offered to present on sending balloons into the stratosphere and using a Raspberry Pi transmitting live images from the flight.
Stephen Cornes offered to present on using a hard drive as your primary drive and also connecting to the Raspberry Pi over serial using the GPIO serial connection.

The 20th January rolled around and after snowing for 3 days I expected the day to be a flop.
Giving myself loads of time I got there for 12:30 with a 2:00 start and began getting things organised.

Then to my joy Dave arrived about 1:00 with 3 boxes of bits and a presentation so I knew it wasn't only going to be me.
We both got ourselves set. Dave in the boardroom with the projector and the theatre seating and me the main area where the show and tell activity was going to go on.

I’d spent the week getting a small cheap remote control car to be controlled through Scratch (see previous post) but due to my mad/bad wiring when I set it up interference between the wires meant the car always wanted to go left. I could show the wheels spinning forward and backwards but the grand plan of having people try to figure out how to program Scratch to get the car to navigate an obstacle course did not materialise.

Alongside my nearly working demo Dave set up his ballooning bits.

Paschal Egan showed using the GPIO to produce 433MHz home automation control signals to switch on and off domestic appliances.

Ian Law brought along his set up to see if someone could help with debugging the Python snake game he was working through from the Raspberry Pi Users Guide.

Robin Fordham set up his circuit that expanded the GPIO pins using I2C controls.

At the far end Leo White brought along his Raspberry Pied BigTraks with robotic arm and webcam.

In the end over 30 people made it out in the snow to attend. An amazing turnout considering the weather. Ranging in age from 15 to a much older.

Once most people had arrived Dave presented Pi in the Sky. I was so wrapped up I failed to keep him to time so we got a lot of details on what was involved.

Then Stephen presented on using a hard drive as your main file system and also connecting over GPIO using serial. His impetus for both was issues with SD cards giving errors and not wanting to have to attach the Raspberry Pi to a screen. If you connect over serial then you even get to see the boot sequence. This is not the case if you SSH in over the network as networking has to be active for the SSH connection to happen.
Stephen kept to time and by the rush of people to the front after he finished his presentation was of interest to a number of people attending.

After the presentations we went back to the show and tell area. Where we mingled and chatted. Those of us with demos answered questions and tried our best to explain what we did, how we did it, why we did and what use it was.

I must admit seeing the BigTraks with the robotic arm controlled by the PS3 controller over Bluetooth and live streaming to a browser was fantastic. It really showed the power of the Raspberry Pi and the number of things it can do at the same time.

There was a crowd around Ian’s Raspberry Pi trying to figure out what was wrong with his code. In the end Robin Fordham came to his rescue and worked out there was a rogue file in the directory with the program causing problems. Once this was deleted then everything worked as it should after a simple typo error was fixed.

From the feedback people have provided it sounds like the event was enjoyable and achieved its goal in inspiring people to do more. One person has invested in a Raspberry Pi, another purchased a Pi Cobbler and others found answers to their questions that would allow them to continue with their projects.

From my point of view as an organiser of a Raspberry Jam I must admit it was quite painless. Just set things up. Let people know it’s on. Manage registration on Eventbrite and then play host on the day.
A few things I would tweak are
Maybe have each person do a 10-20 second intro (name, own a Pi, what done so far, what do you wish to do) so people can connect and also any gaps in the official(ish) agenda can be filled by meeting like minded people.
Keeping presentation to 30 minutes. Extra detail for those interested can be do one on one in the show and tell area.
Have people demoing put a sign or sheet out showing what they are demoing so it’s easier to figure out which projects are of most interest.
Encourage others to take pictures and videos as I was either presenting or running around so took very few photographs and no video.

Here’s looking forward to the next Egham Raspberry Jam.

Friday, January 25, 2013

Went to Surrey & Hampshire Hackspace last night

I heard about the Surrey & Hampshire Hackspace early last year and even attended a meet-up before the summer in 2012 and really enjoyed it and intended to get back there again. Well, finally last night was the night and it was well worthwhile.

One of the members had arrange for us to use a warehouse location in Farnborough and so we had loads of room and bench space with wifi access.

I got the chance to talk to others who were doing interesting things with their Raspberry Pi and also show how an Arduino works and can be programmed.

Eagle Tutorial
Eagle Tutorial from Youtube
But for me the highlight of the evening was a tutorial on how to use Eagle ( by Bob. Eagle is a free or paid schematic diagram program that can also do board layouts.  I have tinkered with Eagle before and even thought I understand the fundamentals of electronics (at a very basic level) it kept giving me errors or not doing what I expected. For where I am now the free version is more than enough for me.
During the session Bob took the simple transistor switch circuit I prepared and used it as the example for finding components, placing them, connecting the nodes and duplicating them. All very useful, so now I can do more with Eagle.  Next time Bob is going to go into even more detail on what you can do with Eagle.

Then after the Eagle session Alan told me about the ULN2003 NPN 7 Darlington Array. Using just this an a SIL resistor pack for the 1K resistors I could do everything that needed 12 resistors and 4 transistors. So, lower cost, lower complexity and more reliable.

2 members of the Reading Hackspace also turned up to introduce themselves and talk about working together so as not to duplicate effort. Since Reading and Farnborough as so close to each other it really makes sense to take advantage of the opportunities this provides.  They mentioned that Reading is just about to move into a new bigger space.

Before leaving I powered up the Arduino and showed the IDE to a couple of people. Ran the Blink example  and then the Web server example just to show how easy the Arduino is to use.

Overall a great evening with some great people in a very open and sharing environment. I learned about Eagle, circuit design, a new component and how to pass command line arguments in Python.

Here's looking forward to next time.

Thursday, January 17, 2013

Raspberry Pi - GPIO - Scratch - Remote Control Car


Tonight I wired up the remote to the circuit and the circuit to the GPIO pins on the Raspberry Pi.
Booted the Raspberry Pi and connected using Putty and Xming to get an Xwindow display on my netbook.

Ran the GPIO Scratch after installing the code I mentioned before.

 The bits of code make the car go forward, backwards and turn (forwards and backwards)

Raspberry Pi in PiBow connected to the circuit for controlling the remote control
 Ignore the Arduino in the picture I just have it attached to the
board with the proto board

When I click on the code blocks the car moved - YEAH!. So, I figured out the controls for the remote.  Make 4 small circuits to allow the GPIO Pins to activate the remote control.  With a massive amount of help from where I got the Scratch GPIO control code from I got Scratch to switch the GPIO pins and made the car move.

The quality of the car was causing some problems as the wheels would get stuck on the carpet.

This was great fun to do and as a possible beginners electronics/Raspberry Pi/Soldering/Scratch project it may suit. Wait a moment that kind of a very specific set of requirements.

Here's hoping the car is bit more accommodating on Sunday.

Wednesday, January 16, 2013

Messing with a remote control car and some transistor

As per a previous post I have arranged a Raspberry Pi event (Raspberry Jam) at Gartner's offices in Egham on Sunday the 20th January.

Originally I was considering setting up my Raspberry Pi on a big screen with the Atari 2600 emulator running and a joystick for some old school nostalgia gaming but then I thought that might be a bit boring.

Since I have volunteered to run a Code Club at my kids school I thought how about something in Scratch.  Code Club uses Scratch and Raspberry Pi has  Scratch so if I did something in Scratch then I could have it at the Raspberry Jam and then also show it to the kids at a future date as an example of what is possible with Scratch.

Code Club does programming I thought maybe something with electronics and since I have an old cheap remote control car gathering dust I thought I'd try to design a switching circuit that would allow the Raspberry Pi to control the car from within Scratch.

My knowledge of Scratch, GPIO and Python are limited so it was lucky that somebody far smarter than me has developed the code to allow Scratch to control the GPIO pins. All the details at this link -
After figuring out I needed the latest image of Raspbian for this code to work I was off.
I did the obligatory flash an LED to make sure it all worked on the Raspberry Pi and it did.

Confident that Scratch could control the GPIO pins I turned my attention to the no name, small, cheap remote control.
Out with the multi-meter to check where the switches went to and how they were wired to the one IC on the board. I figured out that the pins are all held high and then go low to be actioned.
The remote from my testing old uses 0.1mA so it probably would have been safe to just attach it to the Raspberry Pi, but not sure if this was correct I decided to put in a transistor switching circuit that would hold the line high until a high is applied to the GPIO pin for that control and then it would go low. Effectively enabling that button on the remote and sending the relevant signal to the car.

I used a 2N222a NPN transistor for the circuit and again being concerned that my very rusty electronics would fail me I posted to the Raspberry Pi Forum asking if the design was OK including a small circuit diagram.( and amazingly Gert van Loo the Gertboard guy replied saying the circuit was good with a recommendation to add a 10K resistor from the GPIO to ground so the GPIO pins start in a determined state. (Yes, I'm missing a 2 in the image I'll fix it later)

With my head swelling from Gerts positive comments but still not ready to test with my precious Raspberry Pi that I needed for Sunday (plan B of Atari 2600 is still an option) I wired up the circuit to my Arduino who's pins a bit more robust.

Created a small bit of  code that set the pins high and low to see if it responded.

RESULT - the car went, forward, backwards, turned left, turned right.all controlled by the Arduino code

This means the circuit is good.  The electronics of the transistor switches works with the cheap remote  control.

So, tomorrow (Thursday) evening I will wire it to my Raspberry Pi and see if the final product works and then can I control it in Scratch.

If yes, then I will have it with me on Sunday.

Roll on tomorrow evening and roll on Sunday.

2nd Code Club lesson - experience and thoughts

After the first week where only 4 kids turned up this week was a different experience with 11 kids.  Of which 5 were boys and the rest were girls.  So, a nice mix.
The folders I gave the kids the last time were a big hit.  2 of the girls had decorated their folders and some of the new kids had been told about by others what happened the last time and were looking for their folders. 12p folders from the pound shop make you a hero.

The second lesson is the Whack a Witch class where the kids make a similar game to Whack a Mole but with witches. This class can be be downloaded from the website. The final words 'look like this' are the link.

Wit most of the kids having missed the first session I had to go through some of the fundamentals with them but didn't want to lose the excitement and moment of actually doing so I gathered them around one computer and showed them the stage, sprites, and the other bits at a really high level, knowing this wouldn't be enough for them to work on their own but hopefully would give them some comfort with the interface.

What followed was a manic hour of excited kids and a whole lot of one-on-one guidance.
But this time by the end all kids had the game completed.  Some with more support than others, but they all had their game to play and enjoy.  One of the girls who was there last week got it done in about 20 minutes and even started helping others. I think I have found my future helper.  Nothing proves you have learned something than being able to show others. I made a point of telling her mother when she was being collected how great she was and how helpful she was with the others just starting.

I provided a letter for kids that I found here ( to take home for their parents if they wished to explain to their parents what they are doing and also ask to have Scratch installed on their home computers.

Once again the time felt way too short. It's either me or the sessions should be 90 minutes so I've asked the teacher coordinating if we can run the sessions from 3:20 - 5:00.  Giving 10 minutes at the start and then 90 minutes of mad activity.

When the kids had gone and we were back in the class tidying up a great thing happened. Another teacher came in and said while she was in her class she heard 2 boys outside saying how great the club was. Really enthusiastic and excitedly.  So, even though the class was a bit rushed and the learnings were limited due to the speed the No.1 objective I hope for was achieved. The kids were excited and eager to do more.  The learning and understand will come once they master the interface and repeat some of the steps.

So, another successful(ish) Code Club. Roll on next week and the fireworks.

Saturday, January 5, 2013

Egham/Staines Raspberry Jam 20th Jan 2013

Back in October I started the process of hosting a Raspberry Jam at my employers office in January.
It took nearly 2 months to get it sorted but we got there and on the 20th of December I announced the first Raspberry Jam at the Gartner offices in Egham on the 20th of January 2013.

In case you're unaware a Raspberry Jam is an event for people interested in the Raspberry Pi computer. An opportunity to meet like minded people and hopefully get inspired or connect with people who are looking to achieve the same or similar goals to yourself.

I attended a couple at Bletchley Park in Milton Keynes in October and November and was even more convinced that Raspberry Jams were a great idea and well worth organising.

Well, with 2 weeks to go there are only 3 tickets let of the 50 allocated on Eventbrite.

There 2 confirmed presentation, including the amazing near space live images project Pi in the Sky.

Based on the demand so far I'm hoping for a full house and if this one goes well I will work to get it set up so we can have Raspberry Jams regularly at the Gartner offices.

A big thank you to Alan O'Donohoe  @teknoteacher for getting the ball rolling with the Raspberry Jams and also for talking to me about what is involved in preparing a successful Jam.

Here's looking forward to the 20th of January and a successful Raspberry Jam.