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There’s a lot of smart electronics INSIDE A FURBY There’s some very smart electronic technology hidden beneath the cute fur-covered exterior of a Furby. So let’s peel back the fur and take a look at what’s inside. in response to the preferences of the child who owns it. Yes, the Furby can adaptively learn! Throw in a spoken vocabulary of 160 words (capable of being incorporated into no less than 1000 different phrases), the ability of Furbys to automatically communicate with one another via an inbuilt infrared port and then consider the retail cost – around $69 in Australia and just US$30 in the United States! It’s state-of-the-art in a very unassuming package indeed. By JULIAN EDGAR The Furby is a fur-covered pseudo-animal with fixed feet and a movable mouth, ears, and eyes. In addition, the Furby can rock forward on its base platform. The movable parts of the toy are mechanically driven by an internal electric motor (more on this in a moment) which The subject of a child’s toy might seem to be a strange choice for an electronics magazine like SILICON CHIP. But as you’ll soon see, it isn’t. Packed inside a Furby’s 130mm-high furry body is an amazing complexity of mechanical and electronic components – and software. Unconvinced? How’s this then – the software boasts the ability to actually change the toy’s output behaviour 4  Silicon Chip The toy TOP OF PAGE: Furbys come in different colours but internally they are all the same. A smart package of electronics and mechanicals, the Furby shows that not all electronic advances are confined to the esoteric. Furby, stripped of his furry coat and internal plastic carapace. Located between the eyes are the light sensor (centre) and a pair of infrared transmitter and receiver LEDs. Furbys can automatically communicate with one another via this infrared link. operates the eyelids, opens and closes the mouth, and waggles the ears up and down. Also hidden under the fur are press-switches on the front and back and a switch inside the mouth that is triggered whenever the mouth is opened manually. A big factor in the toy’s success is its language skills, with an internal speaker able to clearly communicate “spoken” words and phrases. There are also additional inputs and outputs but more about these later. A short description of the toy doesn’t do it justice; it is the way in which it works which is so interesting. For example, as I write, my Furby (yes, I bought one as part of the research for this story!) is “asleep”. How do I know? – well, it made snoring noises, then rocked forward and closed its eyes. Loud noises or changes in light or other stimuli will not wake it. To rouse the beast, it must be picked up and tilted to trigger an internal tilt switch. By the way, early Furbys were apparently much harder to put to sleep, requiring a certain sequence of events including lots of pats on the back. However, Furby manufacturer Tiger There are entire websites devoted to Furbys and hacking techniques. One of the best is “Blank Frank’s Furby Stimulation Page” at www.veg.nildram.co.uk/furby.htm This photo shows just how jam-packed Furby is inside. A semicircular PC board is located just above the battery box, with the mechanical module mounted on top of that. The sound-sensing microphone is hanging on its lead closest to the camera. Electronics Ltd changed the design, fearing a backlash from exasperated parents. Furby doesn’t have an on/off switch, you see. As an example of its behaviour, I have just picked up This website at http://www.geocities.com/SiliconValley/ Pines/7438/furby.html includes a program that lets you record, save and play back a Furby’s infrared signals. May 2000  5 In this view, the horizontal axis camshaft can be seen, with plastic cranks moved by the cam lobes connecting to the eyes, ears and mouth. The cam position switch is located in the middle of this picture, with the reset switch at the bottom. The wiring harness is held in place with many globs of hot-melt glue. the toy and it has said “Mmmmmmm, me love you”. However, the last time I roused it from its sleep, it said “Sun’s up”. This lack of predictability in response to stimuli lifts the personality realism to a totally different plane compared to most toys. When woken it may have alternatively said, “Me sleep again” or “Cock a doodle do, big light”! Or it might have sneezed, giggled, or made one of many other sounds. Each Furby picks its own name from its available list of sounds (mine says “Me Too Loo”) and individual Furbys have differently pitched voices. If left unstimulated for a few minutes (no noises, no changes in light intensity, or no switches pressed), a Furby will sometimes say “Mmmmm – boring!”. If still ignored, it will go to sleep. When taken for a ride in a car, a Furby will say “Wheeeeee!” whenever the car corners and suggest that it wants to play hide and seek when the intensity of the light suddenly changes. Holding it upside down will initially provoke giggles, changing sometimes to “I’m scared” if it is held in this position for too long. Games There are several games built into the toy. For exam6  Silicon Chip ple, to place a Furby into the “Hide and Seek” mode, the light sensor located between the eyes needs to be covered and uncovered three times and then the front pressure switch activated (“tummy tickled” in Furby-speak). The beast then needs to be hidden within a minute, following which it will be quiet for three minutes. Once this time has elapsed it will start saying “nah, nah, nah” at intervals until it is found. When batteries are first inserted into it, a Furby speaks no English words or phrases. Instead it speaks in “Furbish” and a dictionary with 44 entries lists the English translations. However, after a few hours of stimulation, the toy starts to speak some English and after a day or two, it speaks mostly English. Note, however, that English words are not actually being learned; instead, it would appear that after Furbish phrases and words have been “spoken” a set number of times, that word or phrase is replaced by English. The developmental stage that the Furby has reached is maintained when the batteries are changed. However, there is a reset mechanism that can be activated to return a Furby to infanthood! If a Furby initiates a pattern of behaviour (for example, it makes kissing sounds when the front “tickle” switch is activated), patting it on the back (ie, activating the rear switch twice) will reinforce this behaviour. Consequently, individual Furbys can adopt slightly different behaviours on the basis of their owner’s preferences. So you can see that, from a child’s perspective, a Furby is a very attractive toy indeed. It has a distinct personality (sometimes with negative character traits like belching and breaking wind!), initially has its own language but soon learns English, and has its own demands – if it isn’t fed, a Furby becomes ill and sneezes a lot. It’s easy to see why Furbys have become so popular. The mechanicals As mentioned earlier, an internal motor is used to drive the movable parts of a Furby. This reversible DC motor is mounted to one side of a “movement module” which is positioned inside the top half of the toy. The motor drives a series of reduction spur gears which rotate a worm drive. A 40mm diameter speaker is used. It is capable of quite clear reproduction. The worm drive, in turn, acts on a large cog attached to a shaft which has series of cam lobes. These lobes bear on connecting rods that move the eyelids, mouth and ears and rock the Furby backwards and forwards. Rotating the shaft in a single direction causes each moving part to be operated in sequence. However, because each movable item has its own cam and they are each arranged such that their lobe centre angles do not overlap one another, each movable item can be operated independently if the camshaft is rotated back and forth within a narrow rotational angle. For example, during “dancing” (where the Furby rocks back and forth), the shaft is rotated so that only the rocking motion lobe is operated. This position of the camshaft behaves as a “dead spot” for the lobes that drive the eyelids and ears – so during dancing, the eyes and ears stay still. Because the main worm drive cannot transmit torque in the opposite direction (eg, the motor cannot be turned by moving the ears), a slip mechanism is built into each movable body part. This allows these parts to be manually moved without causing damage. The motor uses sprung copper leaves to transfer power to the commutator. Carbon brushes aren’t used – instead there appears to be some type of conductive grease spread over the relevant area. This probably explains the strong “electric motor” smell that occurs if the toy has been operating continuously (eg, by being held upside down) for some time. The main PC board contains most of the electronic circuit-ry. The position sensor is at top-left, while two daughter boards (each with a custom COB microprocessor) are located at left. The electronics comprises a main, double-sided PC board with surface mount and conventional components on it. Additionally, there are two small daughter PC boards mounted on the main board at rightangles, each carrying a custom COB microcontroller. Serial data is transferred between these two microcontrollers, which are run at 3.58MHz. A 1K 93C46 non-volatile EEPROM is mounted on the main board and this probably contains Furby’s name, developmental state and adaptive memory. It would appear that a separate chip is solely responsible for generating the sound output – perhaps this approach has been taken to allow easy implementation of Furbys that speak other languages. The system’s inputs and sensors are as follows: (1) A reset switch (located adjacent to the battery compartment under the toy); (2) A back switch (senses back pats); (3) A front switch (senses tickling); (4) A cam position sensor (consists of a small leaf switch); (5) A gear speed sensor consisting of a LED which shines at a receptor through four slots cut in a black plastic gear; (6) A ball tilt switch (used to detect level, tilt and upside down orientations); (7) A light sensor positioned behind a panel between the eyes; (8) An infrared receiver LED (positioned near the light sensor); and (9) A feed sensor consisting of a microswitch behind the mouth. The outputs are as follows: What do you do if your Furby “dies”? Tie a toe-tag to him and conduct a thorough autopsy of course. You can find out the cause of Toh Loo-Kah’s untimely death on http:// www.phobe.com/furby/cause.html Furby includes an infrared port for communicating with other Furby’s and can often be tricked into responding to IR remote controls. There’s lots of information on this at http://www.homestead.com/hackfurby/files/FURBYIR.html The electronics May 2000  7 while a pair of diodes is used to provide 5.3V and 4.8V rails for the rest of the circuitry. Infrared communications The microprocessors are “blob” types, custom-made for this application. With the Furby manufactured literally by the million, this approach is very cost effective. The small reversible DC motor works hard for its living; if the toy is used for extended periods a strong “electric motor” smell is emitted! (1) A loudspeaker (40mm diameter with clear plastic cone); (2) An infrared transmitter LED (positioned near the light sensor in the forehead); and (3) Motor forward and reverse operations. The motor is driven at battery voltage (6V nominal) One interesting aspect of the toy is its ability to use infrared transmissions to communicate with other Furbys. Furbys can normally communicate with each other when placed in close proximity, although my sample Furby steadfastly refused to communicate with another Furby whose access was arranged for just that purpose. Apparently, they are capable of transferring colds (the healthy Furby starts to sneeze as well) and developmental stages – a Furby can speak more English after being in contact with a more advanced Furby! For the hackers, the infrared port also allows another pursuit – fooling Furby into doing odd things by stimulating it with foreign infrared signals! IR-emitting devices that people have used for confusing Furbys include PC IRDA ports, purpose-built standalone Furby IR transmitters, the Palm III handheld computer with OmniRemote software, TV and VCR remote controls and even a Nokia 9110 mobile phone! If you want to find out how to do this, refer to the websites listed at the end of this article – that’s right, there are entire websites devoted to Furbys and hacking techniques. Take a look at “Blank Frank’s Furby Stimulation Page” (www.veg.nildram.co.uk/furby.htm), for example. Among other things, he shows you how to control a Furby using a computer’s IRDA port. What, no IRDA port? Blank Frank’s got that covered as well, with a simple circuit that you can build yourself. For the technically-minded, Furbys communicate using IR pulses approximately 150-200ms wide with a bit time of 2ms. The communication packets consist of nine bits sent six times, with silence between each set of nine bits, giving a repeat rate of about 100ms. The nine bits consist of a start bit, four data bits and then the same four data bits inverted. There are 16 different signals that can be communicated. Conclusion A few years ago a self-learning toy that talked, communicated “intelligently” with other toys of the same type and contained internal software that gave a very real sim-ulation of “personality” would have been the stuff of dreams – especially at this price! It shows that not all SC electronic advances are confined to esoteric areas. There’s Lots More Info On The Furby On These Websites Much of the information for this article was derived from the many websites devoted to the history, dissection, hacking and electronics of the Furby. These sites include: (1) http://www.veg.nildram.co.uk/furby.htm (2) http://www.blueneptune.com/~maznliz/marius/furby.shtml (3) http://www.geocities.com/SiliconValley/Pines/7438/furby.html (4) http://ai.tqn.com/compute/ai/library/weekly/aa101398.htm (5) http://www.wired.com/wired/archive/6.09/furby_pr.html (6) http://www.homestead.com/hackfurby/files/FURBYIR.html (7) http://freeload.homestead.com/_ksi0701961574651052/hackfurby/files/furby.pdf (8) http://www.phobe.com/furby/faq2.html 8  Silicon Chip