There are several
websites documenting the original Furby circuit board. I decided
to replace the original circuit entirely and replace it with a PIC based
The mechanism of the Furby itself was designed around micro- controllers.
It has one motor that runs the eyes, mouth, and ears in sequence.
Two sensors are provided from the motor servo system: one counts off about
200 pulses for the entire sequence, the other is an 'index' pulse that
lets you find the start/end of the sequence.
Several other sensors are provided including several switches, IR sensor,
photo sensor, and microphone. The outputs are to the IR system,
motor, and speaker.
A circuit board was cut to a size and shape of the original board.
Because of space limitations, wirewrapping was not possible. Point
to point wiring using clipped pieces of #30 wire was done by hand.
Click here for the current state of the Schematic.
The basic circuit uses-- PIC16F819 microcontroller, FAN8200 H-Bridge
(motor driver), 24LC256 serial eeprom (for audio samples), MCP41010 digital
potentiometer (used as 8-bit D/A), LM386 speaker driver, IR led (for tachometer
sensor), and a mercury tilt switch to sense motion.
software is rudimentry at this time and will be provided later.
So far, the motor drive, tachometer sensor, index sensor, tilt switch,
sound eeprom, and audio system have all checked out. This is one
of those ongoing projects to see just how smart (wierd) this device may