Development of the #ShrimpBot

Development of the #ShrimpBot

At this point I have built the base of the #ShrimpBot.

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Both motors have been checked by connecting them directly to battery terminals.

I have soldered the jumper cables onto the motors & wrapped them in tape to keep them secure.

I now want to begin the breadboard circuit that will allow me to send a signal to the motors to turn them on & off, in effect steering the Bot.

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In order to test the circuit I’m going to use a spare motor & just push the jumper cables through the wholes in the terminals.

I’ve also blue tacked a toothpick to the axle so its clearer in the video to see whether its turning.

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I’m going to be using a modified version of the 3rd circuit from the Arduino Experiments kit to control the motors.
I can’t recommend the ARDX kit highly enough – its a bit expensive but an absolute MUST if you’re new to this stuff!

http://oomlout.co.uk/starter-kit-for-arduino-ardx-p-183.html

To begin you’ll need to take a Transistor (the black three legged fella) & a Resistor (the ceramic type thing with stripes on it).

The exact position of them along the board isn’t important (ie it doesnt matter if you use row 49,50 or 51) but they should create a T shape.

Also it’s important to check the Transistor is facing the right way – the flat side should be facing towards the Resistor.

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The WHITE jumper cable is plugged in next to the Resistor & I’ve just blue tacked that down to make the photo clearer.

This WHITE cable will be the signal cable – it will be the wire that we send our signal down to tell the motor when we want it to turn.

I have also included a powerpack – I bought this one super cheap from radio Shack but you can get them at Maplin & online.

(I feel duty bound to give a word of caution here as I have had 2, that’s TWO ASDA batteries literally explode on me in the last 2 months –

I will include photos of the remains of them in a separate article – I’m told batteries should never explode but one went in the middle of a

lesson & I have 2 dozen year 8 pupils with frazzled nerves who will attest to how loudly the thing BANGed when it went!!!)

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Although the two stages above look like a big jump in complexity all that I’ve really done is add the motor.

I’ve blue tacked the motor onto the corner of the breadboard. I’ve chosen to use RED as the positive/powerIN lead.

The wires allowing current out of the battery are BLACK & it connects right next to the WHITE signal pin.

The following diagrams make this clearer…

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The circuit is essentially putting a tap on the outflow of the electricity.

The Transistor waits for a signal on the WHITE cable & if it receives one it allows current to flow from the BLACK wire

through the Transistor and on down the BLUE wire back to the negative terminal on the battery pack as can be seen here.

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Now we need to work on putting a signal down the WHITE signal cable to tell the motor WHEN we want it to turn.

At this point I would have MUCH preferred to use the #Shrimp (other wordpress blogs deal with my use of the #shrimp)

However I took advice from Tim Moore of Accrington Academy & am using an Arduino in order to remove as many doubts from the circuit as possible.

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The Arduino already has the Blink sketch uploaded onto it.

You can see this if you compare the two photos – on the left there is only the GREEN power led.

On the right photo (above the MEGA chip on the left) you can see the YELLOW pin 13 led is lit.

This means that pin13 is turning ON then OFF constantly.

We want to attach the white signal wire to pin13 so that the motor is prompted to turn ON then OFF.

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Notice:- The white signal cable is being stretched down to plug into pin13.

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 IMPORTANT: The circuit above uses the Arduino’s 5V or 3V power pin as a substitute for the battery power pack. At present the battery power pack circuit doesn’t work. However I can create a working circuit using both the Arduino’s 5V AND 3V power pin but it’s too complex to show the theory of the circuit & I think it’s important for the pupils to see the understandable circuit implemented before giving them a more complex circuit.

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How I got my Wiimote to control a Scratch Game

How I got my Wiimote to control a Scratch Game

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This blog is something of a howto (especially for myself – when I forget how I did it next week &

have to rerun the entire process!!), something of a moan about how many hurdles I had to

jump to get this to work & Im hoping something of an encouragement to similar non technical

‘ICT turned Computing’ teachers who would like to do similar projects and think they are the

only one who doesn’t know their script from their scratch.

Several months ago now @MartinBateman demonstrated a game he

had made in scratch that was then controlled by a wiimote.

Here’s Martin’s presentation from that Raspberryjam on YouTube…

I thought this would be an excellent classroom project to encourage

the kids to make scratch games. Especially if I allowed them up to play it on the

whiteboard at the end of the lesson as a reward for the best design.

So I accessed Martin’s blog & downloaded the Python code he recommends HERE in the video…..

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http://www.star.uclan.ac.uk/~mb/rpjam3sept2012.html

I already have python 2.6 & 3.2 (http://www.python.org/getit/)

so once I’d copied & pasted the code in I thought it would be as simple as pressing run.

Maybe its me being naive but when you’re used to using MSoffice & passing any slightly

technical hiccup to IT support hitting a hurdle that you’re going to have to solve yourself is quite daunting.

Anyway the hiccup presented itself in the form of bad indentation that neither version of python liked.

Given that this was script I had never seen before & my python is still fairly amateur I finally got

it to run & had a momentary swell of pride that I’d dealt with the problem myself.

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That was when it spat back an error message about not having the cwiid library! 8….-(

An HOUR of googling later I slowly started to realise that this cwiid thing is just for

Linux & having searched desperately for a Windows version and finding nothing I had

to accept that it wasn’t going to work for me on a W7 pc.

Feeling uncharacteristically brave after my earlier success with the indents & having

had several cups of coffee at this point….

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I decided – how hard can it be ….. so I googled around and found this game on the Scratch website.

http://scratch.mit.edu/projects/rubiks_cube_guy238/1182359

Again, naively, I just pressed go & expected it to just work… I mean why wouldnt it? 🙂

It didn’t.

I went searching through the associated forum and found reference to something

called GlovePi. Which I then downloaded from here…

http://download.chip.eu/en/GlovePie-0.30_174835.html

I found a tutorial series on YouTube, here…..

& I had to google how to enable my bluetooth here…

http://www.ehow.com/how_5844478_connect-nintendo-wii-remote-computer.html

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I even had to google how to make the wiimote discoverable!

http://nintendowiiremote-with-windows7.articles.r-tt.com/

I C&Ped the code from the scratch forum here….

http://scratch.mit.edu/forums/viewtopic.php?id=87154

into GlovePi hit run & tried to play the game…

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(About half an hour later after finally getting an old bluetooth dongle that actually worked…)

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After fiddling with the code a little (as you can see above) so that I didn’t die

instantly every time I started the game.

I had success!! 🙂

My next mission is to actually learn how the code works – Ive made a start on this already by following the YouTube tutorials about GlovePie mentioned above. So far Ive just turned the lights on & off, but I saw a nice example of counting to 10 in binary using the lights – I think I’ll try that. 🙂

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was done using this code….

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row 2, cell 1 row 2, cell 2

There are some other fun projects using GlovePie and a Wiimote here.

Trying to build the moorebot

“@GeekMoore: @ManchesterBudo @patlink72 you’ve had 5min.” ha! 🙂
Ive no hbridge so I tried running both motors off the Arduino but I think it needs more power coz they both won’t run at once SO im on way to asda for batteries.
I had to solder the cables onto the motors (and you know how terrible I am at soldering- then I wrapped tape round for extra security)
The wires kept getting pulled out accidentally otherwise that was doing my nutt in.

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Servos

Current thoughts are whether I should seek out the CHEAPEST servos online (possibly buying en masse) or stick to the philosophy of making the projects ACCESSIBLE to pupils by using servos that are commonly available from Maplin/RadioShack etc. meaning pupils can SOURCE & build their own projects at home easily as they know they can ask parents/get bus to the nearest shop & within the hour continue building the project.

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