PICAXE® microcontrollers are dirt cheap but powerful & exceptionally easy to use. The 16 offerings now in the PICAXE family (at May 2009-with 6 runout & 1 awaited), are titled by their number of pins (8,14,18,20,28 or 40),& are based around regular PIC micros with specially factory "bootstrapped" non volatile memory. They all simply PC connect via 3 wire D9 serial ( or cheap USB adapters), & program under a free Windows high level editor using ~50 PBASIC "plain English" commands (or also flow charts). Even your dog could understand high, low, nap, goto, sound, if...then, sleep, readadc, pwm etc. The program editor & .pdf manuals (~32 MB) can be downloaded FREE (but first register on line) from www.picaxe.com ,& run sweetly on even an old W95/98 clunker PC - Mac & Linux versions also exist. Ensure you have latest editor versions & updates as new features & commands are continually evolving!
UK developed ( with Oil & Gas industry funding) by Bath firm Revolution Education ("Rev.Ed" www.rev-ed.co.uk), the mid 2002 release of the baby "08" ( based upon Microchip's PIC12F629/675) gave far reaching spin offs for educational & hobbiest users. These "08s" still sell for just £1 (~US$2.50 or Aust/NZ$4), & at this budget price can even be left in the final soldered circuit, with later software tweaking if need be via a convenient 3 pin serial connection. A flexible 3-~5V supply @ ~2-5 mA means battery power (typically 3 x AA) very feasible. Direct LED flashing or piezo sounds are a breeze, & teenage students, often unenthused with "normal" electronics, just love them.
The preferred entry level PICAXE however is now the enhanced 8 pin -but deceptively powerful-"08M"( Music?), based on MicroChip's Dec. '03 PIC12F683 , which has has inbuilt 4/8 MHz resonators,128 bytes RAM,256 bytes EEPROM (~80 code lines),5 I/Os,& 8-10 bit ADC. Aside from it's ring tone capable music, the 08M can even read DS18B20 temperature ICs, encode & decode 40kHz IR data,handle interrupts & generate background PWM. As it's only a modest price increase over the baby 08, this 08M is generally now THE preferred starter.
So just WHY are they called PICAXEs? Although the name is registered ® to Rev.Ed, there's apparently no real meaning. Perhaps they represent a miners digging tool, with "SILICON - I've struck SILICON !" the outcome instead of "GOLD ..." !? In contrast to the agony of defeat & frustration students often feel with hands on electronics, PICAXE circuits usually "just work", & are a great motivational confidence booster. Even students at tertiary level (such at the University of Idaho) benefit from them, perhaps as an introduction to more demanding micros. Picaxes suit technical needs too since they allow rapid R&D that may establish proof of concept in hours rather than months. However the hi level interpreter overhead has a speed penalty,& typically just a few 1000 PICAXE commands are executed per second. Although usually more than enough educationally,especially for control that may take seconds-hours, this execution is naturally S L O W beside the raw speed of cryptic low level programmed PICs !
Folks - if you've been meaning to get into PICs, but thought/found the process akin to mapping DNA sequences,or coding in binary , then these PICAXEs are the answer. The £10 (~US$18) or Aus/NZ $30) Rev. Ed "Starter Pack" is good value, but for more flexibility rugged DIY solderless protoboards may be eventually better. Aside from easing soldering anguish (with associated specialised facilities + lead toxicity issues...),these "breadboards" allow faster component swapping & reuse etc. Although PICAXE breadboard layouts can be very much DIY,it's stressed that hookup wiring should be neat,with simple colour ID & labels etc. Several standard "PICNIK" box (= -ahem- Peripheral Interface Controller Nifty Intro Kit ?!) layouts have emerged,with the refined "Hornblow/Swan" version (as used in "Silicon Chip" articles from 2005) now especially recommended for wetting your feet. Click on the thumbnails below for insights- material is "copyleft" but credit & feedback appreciated.
Australian "SILICON CHIP" monthly electronics magazine (offering online teaser archives,including the opening page of recent articles) Click & open/save the supporting software for featured PICAXE-08/14M/18X/20M articles (2003- ), then copy & paste to the PICAXE Editor
*USA/CAN. SALES OUTLETS ? The well known Peter H. Anderson (Ass.Prof.,Elect.Eng Dept-Morgan State University,Baltimore,USA) is so impressed with Picaxe potential & prices (-note alliteration!) that from Feb. 2004 he decided to bulk import chips, from Rev.Ed thus easing UK P&P/shipping delays. Bravo! His existing US/Can delivery system should make Stateside orders/sales seamless. US educators-support for this appreciated. The official US/Can outlets however are World Educational Services (USA) & HVWTech(Canada), with informal suppliers Ron Hackett (NY)-"3x 08-Ms for $10", & Wulfden (VT) etc.
*HANDS ON EVALUATION ? Productivity driven & wanting cheap,versatile & efficient insights without soldering or health & safety hassles? Check the barebones solderless layout that's shaped up as ideal for initially investigating 08/08M & even the new 14Ms! Such solderless breadboards are sold by DSE etc,but ideal compact ones are ~NZ/A$5 each via Techsoft -techsoft@clear.net.nz & Universal Tech. Supplies,Q'land- epalm@ozemail.com.au. Evaluated & refined designs can then be lifted over 'paint by number' to suitable boards for prototype soldering, pre perhaps a final purpose designed PCB. As well as being the approach followed by the "Silicon Chip" articles, it's been HIGHLY RECOMMENDED BY KIWI EDUCATORS , especially since learners often better appreciate top side circuit views, lacking skills to follow tracks on the underside of PCBs. Hacking a cheap & colourful Electronic Brain Box kit into a so called "Picaxe Junior" also shows promise for both pre teens and weary eyed seniors!
*HELP & ADVICE ? First stop should be the high calibre,friendly & helpful Rev. Ed Forum , but also check the likes of Google Group aus.electronics , US mag. Nuts & Volts BBS , Yahoo Picaxe Group ( join). Parallax Basic Stamps (which began 1993 !) have MANY forums,applications,tweaks & goodies that may suit PICAXEs- "08" code is near BS1 identical of course. Google search too - both Web & Groups. Kiwi 'Frail Dream Dave' has another enthusiastic & lucid well linked site, while the Nexus Research Group (Taranaki- NZ) feature enthusiastic schools PICAXE projects -robotic mice etc ! Fellow Kiwi Andrew has superb pix & schools ideas at his "BrightSpark" & Picaxe Paradise sites -recommended for enthusiastic pre teens & tight budgets. Of course check the insights of the near legendary Rev.Ed Forum guru 'Hippy' .
*SIMPLE DATA DISPLAYS ? LCDs are nice but can run up quite a few $$. Aside from the regular Rev. Ed AXE033 serial LCD/clock 16x2 display, Peter Anderson offers cheap low parts count LCD kits (#105 & #106 etc ) in his esteemed range. Although these come without LCD or PCB (you're really just paying for his PIC16F628 magic!) they look particularly suitable for "bigger screen" Picaxe work, since up to 4x20 LCDs can be addressed. Hippy has even nailed a routine that drives cheap LCDs via a Picaxe-18 (& up)! The Editor's SERTXD command conveniently offers a'F8' miniterminal (& 'F9' serial graphing),but also consider cheap notebooks & terminal programs such as Banana Comm & SelmaWare's StampPlot, which yields Excel .csv graphs too. Older serial organisers (espec. Sharp Wizards ) or Y2k era Casio PV (Pocket Viewers) make "lite" terminals-suit datalogging . A mirrored PVTerminal program for Casio PVs (~15k zipped) is here .
*USB-SERIAL D9 ADAPTERS ? Argh! Your spiffy new PC doesn't have D9 serial ports? Grr-PC makers have been perhaps TOO quick on the draw here. USB/serial adaptors abound, but cost ~A$50 & some give considerable grief to all manner of legacy serial gear- GPS,instruments,CNC etc. Suggest either an older PC (W98 laptops such as Y2K era Toshiba 4xxCDT Satellites especially suitable),a refundable(!) USB dongle, or Rev.Ed's bullet proof Prolific chipset USB010. This latter adapter costs just UK £5, & as well as it's low price is very stylish,compact & reliable. THE recommended approach!
*WIRELESS LINKS?As well as suiting Infra Red (IR) data comms,PICAXEs are near perfect matches with the dirt cheap & compact 433.92 MHz ISM tx/rx wireless units.This licence free band has only modest range (~200m outdoors) & power (~25mW) but suits easy Picaxe wireless serial data links,& even repeaters ,although it can be "noisy". Aside from line of sight (LOS) signal blocking issues,you may have interfering wireless doorbells,weather stations,energy meters & garage/car door openers nearby. Grr! Prior to a more involved data link,& failing a handy UHF scanner,simple site auditing can readily be done with these rx/tx units as well. Also check the simple "Poor Man's UHF " NON DATA Jaycar based 433.92 MHz transmitter & companion receiver TX/RX tone circuits & layouts that also suit Morse beacons,antenna tweakers & hidden transmitter "fox hunting". A new (but still cheap!) 433 MHz "LT" transceiver from US firm,LINX Technologies could suit "2nd generation" PICAXE wireless ? However,even more versatile HopeRF programmable offerings (especially the HM-TR transceiver ), have shown themselves readily PICAXEable , with LOS ranges to >1km.
*ENHANCED APPLICATIONS?! Picaxes aren't just for LED flashing,tunes,kids & education! Aside from use in $$$$ robot designs & Holden car prototypes, an astounding & evolving range of kits & spin offs have developed, with I2C, speech, ultrasonics, colour reading/sorting, 2.4GHz XBee, Web servers, robots, data loggers, servo controllers & GPS offered off the shelf. SMD Picaxes are also available.
* Gadzooks-a Super 8 ! The greatly enhanced Picaxe08-M (music ?) arrived mid July 2004. Based around MicroChip's PIC12F683 (itself only announced Dec. 2003),this 08M offers almost 18A/X features squeezed into a small footprint DIP8. As well as "doubling" 08 offerings (speeds,RAM etc) it handles hi res ADC, IR, DS18B20, peek/poke, servos, background PWM, counts, interrupts & tunes. Looks a winning 08 "next step",at prices (~US$4) just ~20% more than the original 08.
* Confusing your Picaxes with 555s & logic chips etc? IMHO Picaxes should be clearly labelled, ESPECIALLY since their educational use aligns with systematic scientific training.The new 14-M is such a cheap logic IC lookalike that confusion is bound to occur when new users lump all DIP-14 ICs together. Check label samples, although Martyn's multiple 08,08M,18A,18X,28 & 40 exact size printable .pdf versions are recommended, as these suit single page laser printout.
* Victorian lighting ? Lance's Lighting in Melbourne produces nifty PICAXE driven LED lighting kits. Great fun !
* Fancy a challenge? Try designing a working Picaxe-08 circuit to fit (along with battery) inside a 35mm film canister. It CAN be done (via DIY Spider Board )& suits a datalogger or solar power via small NiCd charging etc. However- with the digital camera takeover & likely loss of film canisters- slightly larger "sprinkle jars" (YUM!) may better suit, as these hold cheap & powerful AAs & give more circuit "legroom"
* Easter 2007 surprise! Rev. Ed announce 3 new firebreathing Picaxes, including a 08M "big brother", the 'pin compatible' 14M ,based on a PIC16F684
* Stepper motors interest you? Rescued & bargain steppers are often power hungry beasts needing special motor control driver ICs (L293D etc),grunty power supplies & MOSFET drivers =YIKES & $$! US firm Electronic Goldmine offer a ~US$2 small bipolar stepper that's happy with direct 08(M) PULSOUT driving ! That's right- no other parts needed! Easily stepped & rotated CW,C-CW etc. Dead easy,cheap,extendable & highly educational -recommended for getting your stepper feet wet.
* Early 2009: New 28X2 & 40X2 PICAXEs released, at prices lower than the 28/40X1 PICAXEs previously sold for!
Support site (begun Oct.2002) by enthusiast/educator Stan.SWAN => stan.swan@gmail.comPix via Intel Pocket PC cam. ,Olympus 1.3MPx,super macro 3MPx C-310 & 5MPx Canon A530. Ver30thMay 2010
