The tilt-maze console

The LED matrix is overlaid with a grid printed on transparent film, allowing walls to be positioned through which rolling LEDs cannot pass. The layout of the grid is communicated via a user keypad by typing a code number printed on the overlay. The unit can be pre-programmed with details of up to 100 of these grids, and a further 5 grids can be defined and saved using interactive puzzle editors, also operated via the keypad.

In addition to the LEDs that represent rolling balls, one or more additional flashing LEDs, representing "targets", may be present. These targets do not move when the device is tilted, they remain in the same place. If however a ball rolls over a target, the target is extinguished. The grid may also have one or more cells marked so as to indicate the presence of a "hole". When an LED rolls over such a hole, it disappears from play. An internal sounder provides audible feedback by clicking as the LEDs roll from cell to cell, and bleeping and chirping as targets are extinguished.

The usual objective is simply to extinguish all targets, but puzzles with alternative objectives are equally possible, such as extinguishing all "rollers" by dropping them through holes.

For the technically curious...

Internally, the device is comprised of a 4MHz PIC microcontroller which contains 8K words of flash PROM and 368 bytes of RAM. The 100 LEDs are organised as a multiplex of 4 columns of 25 rows. The 4 columns are strobed in software by a 2mS clock, providing a complete repaint every 8mS, equivalent to a 125Hz refresh so there is no visible flicker. The four mercury switches and the the 4x3 keypad combined to form a single 4x4 matrix, polled by the CPU.

Battery life was obviously a major design consideration. Powered by four alkaline AAs, it has been found that in practice typically 15-20 hours play is possible without any noticeable deterioration in brightness, and up to 40 hours before the LEDs become excessively dim. For simplicity of operation, and to avoid the use of potentially unreliable cheap mechanical switches, switching On and Off is performed via keypad sequences. When "off", the PIC is actually placed in low-power sleep mode, drawing only a few microamps, presenting a drain which is negligible compared to the batteries shelf-life.

I experimented with the possibility of using the LED matrix to provide scrolling text for user messages, with a custom character generator tailored to the 10x10 display. This was not particularly successful as it turned out to be a bit like trying to read a newspaper through a microscope! From longer distances (10 to 30 feet), the scrolling text was highly legible despite the limited display size. I have not developed this aspect any further other than to add a novelty feature - you can turn the unit on either side, or upside down, and a scrolling banner reading "Roll-Play, from clickmazes.com..." automatically self-rights itself and so always reads horizontally.

Further development, if I can ever find the time, may centre around some kind of animated display on the LEDs, accompanied by appropriate bleeps and jingles, to provide the "reward" when a puzzle is solved.

Bill Mitchell - 2001