Here’s my initial prototype. You may notice it’s not too watch-like yet!

 

The main goal of this stage of the project is to build an easy-to-work-with prototype to verify my ideas.  It must be easy to modify because I’ll be making lots of changes.

 

The only “real” part in this design is the display, which is good because it’s the most important part of the watch. Nothing else shown here will be in the final design.

 

The big green board is a Microchip PIC USB development board. I’m using this mainly because I’m familiar with it -- I can modify some existing software I’ve got for it to add the game features.  The actual chip (under the orange wires) won’t be used in the final design. Although it is low-power, it is a bit overkill (who needs USB on their watch?) and the package is too big to fit easily in the case. Because the software is in C, a lot of it will be reusable in the final design.

 

One big question in the design is the power supply. The amount of current needed by all the parts, along with the battery size, determines the size of the battery. This prototype, luckily, doesn’t address that issue at all. The USB connection provides 5 volts to the processor. The black chip at the top left of the white protoboard converts this to 3.3v for the display to use. The resistors at the bottom of the protoboard lower the voltage of the data signals so that the display does not receive too much voltage. The red and black clips going off to the top connect to a large (about 15 pounds!) 12 volt power supply, which is also used to power the display.

 

Here is a video of the initial software in action:

 

The score counters have been modified so that they increment on every bounce - this is just to check that all the digits display correctly and that the counters roll over on the proper interval.