Monday, November 3, 2014

Preparing for 2015 after school computer club

Over the past 2 years I have done a Code Club at my kids school using Scratch and last year included a bit of Arduino. Now in the UK computing is part of the school curriculum so the Code Club learning is now done in school time meaning there is not need for it to be done after school.
With this in mind for 2015 I've decided to ramp up the difficulty and go Arduino all the way with a robot course.

This time limited to 10 kids working in pairs as the complexity is higher and the projects will most likely be done over multiple weeks.

This will give the ability to build everything from a pre-programmed robot to a line following robot or an object avoidance robot. Also included an infrared sensor and remote so the kids can make a remote control robot.

All going well the kids will also be able to decorate their robots with unique bodies to make them more exciting.

In addition to the parts below I also have 36 rechargeable AA batteries for the club.

I'm looking forward to January already.

Below are the list of parts I plans to have for the 8-9 week club. 5 kits

ItemeBay LinkPriceQTYTotal
Robot Deck£7.485£37.40
DC Motor H-Bridge£1.555£7.75
Arduino Nano compatible£2.895£14.45
5 x Breadboard 400 tie£9.491£9.49
Line following sensor£1.195£5.95
10 x Ultra Sonic sensor£8.991£8.99
Infrared sensor + Remote£1.355£6.75
Wires M-M£1.991£1.99
Wires M-F£1.991£1.99
Wires F-F£2.241£2.24
Keypad 4x4£0.995£4.95

Tuesday, October 14, 2014

5th Egham Raspberry Jam - 5th October - Report

A year after the 4th Egham Raspberry Jam the 5th Jam was held.
A bit of fun getting it organised but in the end it was really worth it.

I put the list in Eventbrite and the Raspberry Pi Forum with a month to go and began tweeting and spreading the word.

With such a long gap between Egham Jams I was wondering if people would turn up.

On the day about 40 people came which was fantastic and there was a brilliant variety of projects on show.

Everything from home made conductive paint being used to add glowing eyes to Halloween pictures to 3D printers controlled by Raspberry Pi.
There were (count them) 4 robotic arms. A scalextric controlled from Scratch. A section of model train train controlled using the DCC protocol from RISC OS.
A Thermal printer that gave you a crossword, word search or Sudoku at the touch of a button and a nice big robot that looked like it could do some serious moving.

Also Stephen Cornes did a fantastic timelapse video of the day. For some reason I cannot embed it here. Not sure why but the link is below.

Roll on the next Egham Raspberry Jam.

Below are some of the pictures from the day.

Raspberry Pi model B+ composite/RCA video/audio adapter

With the release of the Raspberry Pi model B+ the previous arrangement from the A/B of having a 3.5mm stereo audio jack and an RCA for video has been changed to a single 3.5mm jack that includes stereo audio and the composite video.

I kept reading online that the arrangement was the same and the iPod and also the Zune so there are loads of cheap cables and adapters out there that work.

After lots of searching I found a number of cables that looked like they would work, but since they were all cheap no specifications for the wiring were listed.

From the Schematic ( the arrangement needed from tip to base is.

Tip - Audio Left
Band 1 - Audio Right
Band 2 - Ground
Base - Composite Video

It doesn't really matter if the audio connections are reversed as you could just swap the leads, but getting the ground or the composite in the wrong position means no video would be output and in the case of ground no audio also.

So, I went mad and took the plunge to buy a £2.00 adapter from eBay and see if it works.

Here it is plugged into the Raspberry Pi Model B+

RCA/Composite video adapter for Raspberry Pi B+

It covers the HDMI port which isn't a problem. As, when I'm using composite I'm not using HDMI.

I am delighted to say it works perfectly. The wiring is correct. I plugged it into a television and up popped the display from my RetroPie install. Playing Double Dragon on the big screen.

Double Dragon played over composite with stereo audio
The price was only for the adapter, but I had an RCA cable from my kids Karaoke machine, but if you don't have one handy then this one for £1.99 also from eBay would work.

Meaning for £4.00 all in you  have an adaptor for B+ to connect to composite and analogue audio as well as the required connecting cable.

I like that it is a 2 piece configuration as a composite cable can have other uses.  I spliced one before to work with an Arduino and the TV-out Library.

Gathering more bits.