■ FIGURE 10. Software
Flowchart for pump control.
of people were very interested in
(A) seeing how the final product would
IF IT DON’T FIT, DON’T
■ FIGURE 11.
Now that I had the basic building
blocks of code, I started to try and
string them together to get true game-style operation. For starters, I needed
to track four paint shot buttons, four
joystick directions, the number of
paint shots remaining, how long the
pumps ran, which pumps were on,
when they should be turned off, what
sound effects were playing, and how
much time was left before the game
was over! I very quickly realized I was
not going to make all this fit in my
(B) trusty BASIC Stamp II chip.
Luckily, I had a Parallax BSIIp24
chip. This chip has eight memory slots.
I could fit eight times the code into
this chip and it was three times faster
than the BSII. It would be even better
at handling all the complex tasks that
had to happen (in what appeared to
the end user) as being in parallel. This
turned out to be a very good choice
as I soon discovered that, not only did
I need to make the game work as
described above, I had to build other
modes of operation such as “Game
Over,” “Maintenance,” “Setup,” and
“Attract” modes. In my final design,
each of these options received its own
slot in the BSIIp24.
Though the BSIIp24 had more
memory than the BASIC Stamp II, it
still had the same number of pins.
With all the features I was adding, I
was rapidly running
out of I/O on the
chip. I turned to my
friend Paul Atkinson
(yet another Robot
Group member) to
help with the overhaul of the prototype
board. Paul designed
and etched a PCB to
hold a 74LS165 input
multiplexer to handle
■ FIGURE 12.
board Rev 2.