Intro: Furby Brain Surgery
Maybe you have a sick Furby which doesn't act properly.
Maybe you have a dead Furby. How you got it is not important.
Maybe you want to see how Furby works.
Maybe you want to make Furby into a animatronic puppet.
The goal of this project is to strip Furby down and remove his brain, leaving his other functions intact.
Personally, I intend to stick another microcontroller in there.
What you choose to make Furby do is your business!
I used two different Furby toys for this demo.
Doesn't this one kind of look like Katy Perry?
Step 1: Split Furby's Seams
Furby's skin is mainly held on with a zip-tie around the base of his body.
First, expose this zip-tie by cutting the single string that ties the cloth around the head of the zip-tie. I recommend a seam-ripper, but a pair of scissors or a scalpel (!) will do.
Now you can see the head of the zip-tie. Unless you can figure out how to undo a zip-tie, you must cut through this sucker. I recommend wire cutters.
Furby's skin pulls off like a sock, or like someone's shirt, until you get to his face.
Step 2: Remove Furby's Face
Furby's face is screwed into his skull. Remove the two screws, one on each side.
Continue removing the pelt and you'll notice just a bit farther up there are two things still holding his face on.
Firstly, the pelt is glued to the skull surrounding Furby's plastic ear stalks, on one side his outer eye ridge, and on the other, the back of the base of his ear. It's a weak glue, probably just to tack the fur down there so his face doesn't get loose, and you can easily pull the fur free.
Secondly, there is a hook holding the top of Furby's face plate. This is an open hook; you can slip the plastic loop behind the open end and free the face.
Continue removing Furby's fur until you get to his ears.
Step 3: Free Furby's Ear Bones
Furby's ears are plastic bones with loops on the ends.
Furby's pelt is sewn to the ends of these loops with a single string, usually the same color as his ears.
Cut through this string; I recommend a seam ripper or scissors.
Furby's pelt should be completely removable now.
Step 4: Remove Furby's Carapace
Furby has an exoskeleton like an insect or mollusk, a carapace.
This shell is in two halves, and a button on his back. The two halves are held together with screws.
Depending on which generation your Furby is, these screws may look different, but don't panic - they work the same way.
Unscrew all the screws, including the one at the top of his head on his right side.
Pull apart the two halves.
Be careful when you remove the right side, because that is where Furby's sound sensor is - his "ear." The sensor is not glued in, but is connected to the board by long wires.
Step 5: Flip-Top Furby
At this point you may notice Furby's skeleton is hinged at the front, but will not open very far. This is because his speaker is in the way, and wires are preventing him from unhinging.
First, unscrew the speaker. There are two screws.
Next, unplug all Furby's wires from their terminals. Some of these are required to be unplugged first to get to others.
On the left side, disconnect the speaker and belly sensor (red, black, brown, orange wires all twisted together), then disconnect the motor (red and black). Both of these must be unplugged in order to free the two green wires, connected to area "S1," which run to the RESET button underneath Furby's tail.
On the right side, disconnect the tongue / gear encoder interrupt wires (ed, black, brown, orange wires all twisted together) and the IR send/receive and light sensor wires (red, black, brown, orange, yellow and green wires all twisted together). This will free the power lines, two long wires which are red and black and run to the battery compartment.
Now with both the RESET wires and power wires freed, you can flip Furby all the way open.
Step 6: Free Furby's Board
You may notice at this point a spring sticking out of the bottom of the circuit board. This is a rod attached to the main cam which makes Furby lean forward or back. It will pull out and is not attached to anything.
Unscrew the two machine screws holding the circuit board to the hinge. Yeah. Now Furby's innards are completely removed from his base.
Only one screw remains - it holds the board to what remains of Furby's skeleton and gears etc, which we'll call his "motion." This screw is different from the others in that it has a plastic stand-off on it, like a little washer. Unscrew this screw.
The board is now free.
Step 7: Furby Board Anatomy
Here's the good stuff:
In order to intelligently hack around Furby's board, we have to understand which parts are doing what.
Note that there is a ton of hot glue inside Furby! Go ahead and remove it to see parts better.
At Furby's left rear, there are two daughter boards sticking into the main motherboard - these two boards are Furby's brain, but not his memory. The contacts for both boards can be seen from the bottom.
The larger board carries the main processor which controls Furby's sensors and motor and all his control logic. WindowsDevPro points out this is a SunPlus SPC81A which is a RISC processor with 80K of onboard storage, which is mostly devoted to storage for the co-processor.
This co-processor is on the second board, which is a TI50C04 speech synthesis chip and which handles the Furbys voice as well as IR communications. For more information, look up data books on the TSP50c0x/1x synthesizer family.
Close by, there is a EEPROM - this is where all Furby's "memory" is - not memory in the computer architecture sense, but Furby's actual "memory" which includes his name, which words he's learned, and the voice the voice synthesis chip should be using.
Next to a small grid of resistors is a quad comparator - this is for the IR communication sensor/emitter and Furby's primitive "ear" microphone.
At the left front is s black round barrel. This is the tilt sensor, which detects if Furby is tilted or upside-down.
HACKING NOTE : Right next to the tilt sensor is something very important - R36 and R37. These are the resistors for controlling Furby's motor. If you want to control Furby's motor, and don't want to remove his brain, and also don't want to build your own H-bridge, this is where you drill - from the main processor to the motor, they are before Furby's H bridge, whose transistors you can see lined up at Furby's front edge. If none of that made sense to you, just ignore this entire paragraph.
The yellow wires you see in the photo of the area labelled "S3" are for the "back switch," which Furby uses to feel you petting him (awwww). These are pretty fragile wires but easy to reconnect. They attach to the switch at the base of Furby's spine - although it doesn't matter which goes where, Furby comes with the wire in the small hole connected to the outside contact and the large hole to the inside.
Finally of note is the LED at the front right of the board. This LED is actually pretty important, because it's how Furby's brain detects movement in the cog and motor. However note that this LED is powered from the main processor... so if you're replacing that board, you have to get power to this LED.
Step 8: Excise Furby's Brain
Now that we know what to look for, look again at the bottom of the board where the daughter boards connect. For my purposes, I just needed to remove the main processor.
Notice that although both custom chips are covered with a black goo for copy protection, they both have open-hole contacts for each pin, possibly for testing at the factory. If you wanted to be pretty crazy about it, I suppose you could somehow disable the processor and use these holes as easy contacts to avoid the pain of re-soldering all these tiny pins. But I'm doing this the hard way:
Take a soldering iron and some method of solder removal - I used a desoldering tool, the kind that looks like a giant syringe with a spring in it. Heat each contact and suck out all the solder.
When there is almost none left, take a blade, like a box cutter, and cut along the seam.
Even though all the solder is now gone, the board may be tricky to remove. With needle-nose pliers, gently wiggle the daughter board back and forth. Now yank it like a rotten tooth!
Congratulations - you have now completely lobotomized Furby. The slot where the processor used to be is now available for a new microcontroller.
For further research on Furby's hardware, check out: