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PICAXE "snap connector" kids microcontroller kit!

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Here's an nifty approach that fits a UK sourced PICAXE-08M micro-controller into the gutted sound module from a colourful "snap connector" electronic kit. It's designed around the simplest ( & cheapest!) 80 experiment kit,but larger versions could be also used.

Popular & CHEAP high level PICAXE micros are widely considered THE best value educational micro, but pre teens & fuzzy eyed seniors may find PCB soldering & breadboard circuit assembly too fiddly. The modification,although a junior version, still allows full PICAXE programming (~80 lines of high level PBASIC code), but only 3 ( or 4 with the ground connection "hack" ) of the normal 5 I/Os are initially available - quite enough for intro work! Sounds,LED flashing,sensor reading,timers,data loggers,simple reaction games, code sending, traffic light simulations etc- even 2 wire serial data comms to other units/PCs are possible. Basic electrical circuits included with the snap kits themselves of course can still be used.  EXTRA - July 2011:   A new firebreathing PICAXE-08M2 has just been released, & it's an easy swap for the original 08M featured here. Such enhanced  features as touch sensing  make it particularly tempting for a Brain Box transplant- refer http://www.rev-ed.co.uk/docs/picaxem2.pdf
 
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Step 1:

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These "snap connector" kits are globally sold under a variety of names, but here in New Zealand they're known as "Electronic Brain Boxes", with the simplest "80 Experiments" offering only ~US$15.
Pre-teen kids thrive on them,& classroom management is easy, since no tools are needed. That's right teachers- NO TOOLS NEEDED!

I've used a swag of 30 as part of my educational "mad scientist" work, & had ~1000s of hormonal kids tinker with them in the past 18 months. Amazingly however most are still intact & almost NONE OF THE PARTS HAVE BEEN LOST. The design of the kits in fact cultivates compulsive tidying up-complete sets have been reboxed in as little as 3 minutes!

Young kids (some even preschool) have absolutely LOVED them, & the confidence boosting gained from assembling CIRCUITS THAT WORK is immense.

Step 2:

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"Friday afternoon on a hot day", but note the ~25 engaged pre-teen kids! Issuing & repacking takes just minutes, & even the simplest "80" kit keeps a class focused for ~45 minutes. Working in pairs is often the best approach.

Step 3: Confidence boosting!

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How about this for pre school enthusiasm- kids don't even have to be able to read,as the colourful instructions are very graphical. And "Girls can do anything" too - hands on electrical fun has often been considered "boy's stuff".

Step 4:

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Even the larger versions may however only provide a few hours of fun "as is" for most kids,& an enhanced challenge is really needed to stimulate curiosity. Teachers & parents COULD of course make up their own experiments & task worksheets - Ohms Law,series/parallel loads & switches etc. The larger kits even have radio & metering options,suitable for mid level secondary school etc,& add ons are available.

Step 5: "PICAXE" that noisy sound module!

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But here's a low cost,& end user orientated, approach instead. Although the basic circuits are highly educational,both kids & (ESPECIALLY!)adults may soon tire of siren & machine gun noises from the kit's sound module. Hence, consider removing this C.O.B. (Chip On Board) device from it's "snap" housing & replacing it with a far more versatile PICAXE-08M micro instead!

An alternative would be to make your own PICAXE add-on,but it wouldn't look as professional,& suitable snap connectors have also been elusive here in NZ.   US firm Elenco in fact offer just such a PICAXEd "snap circuit" kit, (refer => http://cs-sales.net/nsnmiistfrel.html ),but it's at a heady  ~US$120 !  Although Amazon sell this cheaper ( refer => http://www.amazon.com/Elenco-Snap-Circuits-Micro-Standard/dp/B002MRC106/ref=pd_sbs_op_5 ), this is still costly for what there is, and shipping costs may be daunting...

Step 6:

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A Dremel readily & neatly exposes right back to the solder tag contacts- existing wires are rather too flimsy & a full trapazoidal cutout gives best rewiring access. Use colour coded wires (Brown=1, Red=2, Yellow=4 etc) to ID the connections,& DIP 8 socket the PICAXE- perhaps using a Veroboard offcut. Note the PICAXE I/O "PIN" channels are NOT the same as the usual IC legs, & an unusual supply pinout also exists (IC leg 1 is +ve,8 is ground)   EXTRA:  Refer to the ground connection enhancement, a few steps on, that now allows pin 0 to be also used !

Step 7:

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The pain of tight clearance soldering can be eased with a "helping hands" support. Use every trick in the book for such fiddly work!

Step 8:

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Here's the PICAXEd converted layout all ready to fit & finally solder into the gutted holder. If quite a few of these conversions are being done, then set up a simple spacing template to streamline assembly & wire lengths etc. EXTRA:  Refer to the ground connection enhancement, a few steps on, that now allows pin 0 to be also used !

Step 9:

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FINISHED. Yes-agreed-this retrofitting modification is a tad fiddly,but the wiring is not really critical. The small piece of Vero board makes for the neatest assembly,although a "rats nest" ugly layout can be used OK. Aside from the 5 links to the gutted module's connectors, 2 resistors & a 3.5mm 3 terminal socket are also fitted to allow programming. EXTRA:  Refer to the ground connection enhancement, a few steps on, that now allows pin 0 to be also used !

Step 10:

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Programming,using the usual PICAXE 3 wire serial lead connected to an editing PC,can be readily done via the 3 terminal socket. Extra circuitry (LEDs, 10k pullups etc) can be made simply made by modifying 2 section "snap" strips.The speaker should strictly have a 10 microFarad electrolytic & resistor fitted too. Extra LEDs will need a dropping resistor (~330 Ohms). The PICAXE-08M itself runs on a supply from 3-5.5V,& use of a dummy cell allows either 3 x fresh AA cells, or 4 x 1.2 V NiCd/NiMH to be initially used. When they're weary,the dummy can be replaced with another near flat AA! Squeezing a few more useful Joules out of the batteries is environmentally(& tight budget)friendly.   EXTRA:  Refer to the ground connection enhancement, a few steps on, that now allows pin 0 to be also used !   

Step 11:

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Et voila- here's a suggested layout.The "PICAXEd" sound module looks right at home amongst the colourful parts! Make a simple neat lable showing the I/Os & supply positions of course.

N.B. The dummy cell,shown here as a shorting screw for effect,can be more elegantly made using a nail inserted inside a suitable piece of bamboo. As the PICAXE itself only draws a few mA (at supplies ~3V- 5½V), the batteries may last months under easy loads. N.B. A benefit of retaining 4 x AA cells is that weary ones at hand, even with voltages too low for normal use, can be still put to use in the kit. For skinflint school budgets cost savings may be quite appealing!   EXTRA:  Refer to the ground connection enhancement, a few steps on, that now allows pin 0 to be also used !

Step 12: In use!

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Finally grab an old laptop -preferably one with serial ports-download the free editor (=> www.picaxe.com ),& there you have it. Hours of educational fun for youthful bright sparks! Even sprightly seniors (she's 100!) can now handle the setup- you're never too old for learning about micros. FURTHER PICAXE RESOURCES & INFO => www.picaxe.orconhosting.net.nz/snap.htm

Step 13: October 2009 update -extra output !

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A simple & neat enhancement, involving a new ground connection, has now utilised the initially neglected Pin0 (output only) as an extra output . This has shown itself particularly handy for controlling more LEDs, sound making, simple stepper motor insights, & even just "winking LED" program download verification.

Pin 3 ( input only on a PICAXE-08M) remains unused, but scope for IR data reception exists for those with nimble fingers (refer later steps !) These handy 3 terminal devices need just +ve supply, ground & Pin3 data connections (plus a pullup resistor from the data pin to +ve). The PICAXE manuals offer extensive insights into their connection and use- enhanced IR handling comes included in the PICAXE-08M command set.

Step 14: Pin 0 - extra output -wiring

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The extra output is very handy, allowing even simple stepper motor driving!. See details => www.picaxe.orconhosting.net.nz/snap.htm Flying leads could of course be used for the battery supply and ground, but experience has shown that these are vulnerable to student blunders!

Step 15: Vero offcut assembly?

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Although a "rats nest" layout could be used, it's probably worthwhile standardising around a neater assembly if several kits are to be converted. Nothing is too sacred, but the small Vero board offcut shown here made for a streamlined approach. The 8x6 Vero approach shown has been found the most productive in fact, especially since it allows most assembly to be done "in the open " rather than in the confined recess. However YMMV !

Step 16: Vero board offcuts- layouts

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Here are the alternative mounting schemes- both now offer the extra Pin0 connection, with supply ground now wired to the small bolt. The PICAXE-08M socket & programming resistors perhaps best mount on a 6x8 hole offcut of Vero board. Simple BBROYGBPGW colour coding of the wires (0=black, 1=Brown, 2=red, 4=yellow) can greatly help wiring. Note the lower picture clearly shows the unused PIN3 holes, which suit input from a Vishay TSOP 3 lead IR detector (along with it's usual pullup resistor.)

Step 17: Simple "2 snap" strip hot air gun right angle conversion

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A small mounted bolt neatly grips an angled 2 strip ( bent 90 degrees with a hot air gun)- good board layout space is available for this new GND connection! The previous 0V now rewires as Pin0. A significant safety issue of such a ground connection is that supply connection blunders become somewhat less likely! Educationally such a solid terminal even looks akin to chassis ground connections seen in wider electrical use.

The setup here in fact suits all manner of intro. PICAXE driven investigations. Such inbuilt commands as HIGH, LOW, PAUSE, WAIT, SLEEP,SOUND, PWM etc allow LEDs to be flashed & sequenced,delays produced, and diverse sounds and tunes rustled up. The Revolution Education PICAXE manuals offer extensive insights into command use, while the authors article resource site has many "copyleft" examples http://www.picaxe.orconhosting.net.nz

Step 18: Reaction timer layout

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A simple hack of a 2 snap strip allows mounting of a 10k resistor, to provide "gentle but firm" pullup action. This suits READADC use when reading senors, but can also handle switches. The layout here suits a a reaction timer challenge, with scores indicated by a series of beeps following the 10 round challenge. Even the games hardened found it "pretty cool" ! The code, originally devised in 2003 by father & (11 yo.) son Tom & Bob LYNAS is hosted at http://www.picaxe.orconhosting.net.nz/snapreact.bas

Step 19: Traffic lights?!

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Almost everyone has experienced the sequenced action of traffic lights, so these make for a realistic simulation. The momentary push switch even allows pedestrians to interrupt the traffic flow (yeah- eventually- just like the real thing...), and the "Cross Now" buzzer sounds ONLY when the lights are red. The basic code, of only ~a dozen lines, is hosted at http://www.picaxe.orconhosting.net.nz/pedx.bas

All manner of "what if" tweaks can be investigated- perhaps an "amber before green" alert that's used in some countries, or an increasingly urgent "hurry up" buzz for pedestrians ? Check http://en.wikipedia.org/wiki/Traffic_light#Light_timing_length for insights !

Step 20: NPN power strip

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A modified 3 snap link allows a beefy NPN power transistor "power control strip" , suiting PICAXE DC motor and lamp control.

Step 21: DC lamp and motor control

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Here's the PICAXE controlling a grunty filament lamp via output pin 2. Unlike LEDs, these lamps draw 100s of mA & hence can NOT be directed handled by a PICAXE. For simple demo work perhaps interestingly control the kit filament lamp under PICAXE generated PWM etc. If the Brain Box kit motor was used as the load instead, then a small ~100nF cap. across it's brushes stops motor hash problems, while a diode handles self induced EMF concerns. Other sensors could perhaps be extended off board by the flying leads now included in some kits - classic clip leads will be suitable too.

Note the use here of the kit LDR & (DIY) 10k resistor in a voltage divider network, read by PICAXE Pin 1. This could readily allow a much more sophisticated day-night switch to be rustled up than traditional on/off discrete types. ( The 3 snap link from output pin 2 to the transistor base pases over the voltage divider links at pin 1, with no connection made)

Step 22: IR control !

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Extra: June 2011-after some thought & tight wiring trials it was found that a 3 leg Vishay TSOP IR sensor can just be neatly fitted too. As the 08M handles Sony style IR with inbuilt commands,this now allows all the 5 PICAXE I/O pins to be accessed, even though Pin 3 ( which is input only) is restricted to IR data. All manner of off board IR control can then be organised- lights,sounds,delays,sensors etc etc. Magic!

Step 23: Stepper control - with IR enhancement!

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A tiny Electronic Gold Mine bi-polar stepper draws ~20mA unloaded, and can be directly controlled from 4 PICAXE output pins. This can be extremely educational for learners wanting stepper insights, but daunted by "normal" stepper setups. Refer circuit details & code at www.picaxe.orconhosting.net.nz/stepdemo.jpg , with a working video clip www.youtube.com/watch?v=l_F0NyVMXgo Note -this EG stepper runs well on even 2 x AA cells, so back EMF issues that may normally arise can be neglected.

For perhaps the simplest stepper controller going, use a Sony style IR remote (when sensed at PICAXE Pin 3). Stepper reversal & all manner of entrancing motor sequences can then be rustled up!

Step 24: Kiwi kids at "work"!

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End results- here are diverse groups of Kiwi kids ( 7-11 yo.) exploring ideas with PICAXEd snap kits. The old Toshiba W98 serial laptops used for editing are quite suitable for such cost effective insights. Somewhat predictably flashing LEDs, sounds and simple games catch youthful attention - the reaction timer is particularly popular with competitive boys!

The real benefit of the modified kits at this level relates to mind extending investigations that can be carried out. Typical has been a night light "with attitude",controlled by an IR remote. Basic day/night PICAXE managed circuitry can be organised via READADC and a voltage divided LDR of course. Simple security setups that alarm only after PICAXE produced delays (rather than immediately) make for a clever way to catch rascals too! Parts not issued with the kits can usually be organised with spare 2 & 3 snap strips, witness the DIY transistor "power strip" & 10k "pull up" resistor. Other sensors (thermistors especially) can be mounted in a like manner, and even a PV cell ( rescued from a solar garden lamp) may appeal.

Although the IR feature allows all manner of "wireless " links, a tempting extra is a simple FM transmitter for sounds & audio coded data to be sent to a nearby FM radio. The likes of a simple "Swan Code", with tens = long & units =short (hence long,short,short,short =13) can suit for numeric data. Sequential Multi-Tone (SM-T) Hellschreiber can even be sent across a room as" twinkling audio" - refer YouTube http://www.youtube.com/watch?v=1WzFX0snzqM&feature=mh_lolz&list=HL1308887376

Despite it's obsolesence, I've found even classic Morse Code still intrigues many preteens in fact. PICAXE Morse generation is pretty straight forward, and being able to recognise SOS ( .../---/... ) may one day save a life!