Skooks Pong - EEWeb

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DESIGN
I designed the binary clock based on the graphic below:
The above graphic shows how a binary clock should
be positioned to function correctly. I used six LEDs
to represent the hours of the clock. Seven LEDs will
represent the minutes of the clock. Finally, I used seven
more LEDs to represent the seconds of the clock.
With a total of twenty LED’s to represent a full 24 hour
clock, however, this isn’t the only way this particular
binary clock can be setup. I initially thought that the
LEDs cycled from the top eight to the left bottom one,
in a sort of carry effect, but each row stands for its own
number of time, as in a single row cannot exceed 15
from binary converted to decimal. In relation to the
binary clock, a single row cannot exceed 9.
There are limitations that come with the BSHWB. There
are only 16 I/O pins available for use. There are 20 LEDs
that are needed for a full clock as shown above. For
this specific design, I wanted to limit the parts that are
used, in order to reduce clutter, and cost. Unfortunately,
functionality is also decreased with fewer parts.
The above clock could be created using only 16 pins, but
a couple different integrated circuits (ICs) would have
to be used. The simplest way would be to use 14 pins for
the minutes and seconds sections of the clock. The rest
would have to be interfaced through at minimum four,
four-output demultiplexers. These IC’s require three
inputs and only give you one extra output. Obviously,
I didn’t want to clutter the limited breadboard space I
had with 4 ICs. So, for this project, the I eliminated the
seconds, as shown below.
Now only 13 I/O pins were used, under the assumption
that most clocks do not have the seconds displayed.
Most binary clocks do include the seconds section, but
with these seven LEDs removed, three extra I/O pins
were now available for added components.
In order to make this design a little more original, I wanted
to add the functionality of switching the clock over to a
12 hour mode. Usually, binary clocks feature only a 24
hour display mode. To do this, I needed a pushbutton
switch, as well as an extra LED. The pushbutton would
allow the user to switch between 12 hour mode and 24
hour mode. The extra LED would notify the user when
the clock is in A.M. (off) mode and P.M. (on) mode. The
list of parts are detailed below:
• BASIC Stamp HomeWork Board
• 9V Battery
• 14 LEDs (7 Yellow, 6 Green, 1 Red)
• 14 – 470 Ω resistors
• 1 – 220 Ω resistor
• 1 – 10 kΩ resistor
• 1 – pushbutton
• At least 1 extra breadboard
• Sufficient amount of wires
For this project I decided to use 470 Ω resistors between
the I/O pins and the LEDs. This is not the only way to set
this project up, but I felt that 470 Ω is the right amount
to get the desired brightness out of each LED. Another
commonly used resistor that would work just as well is
the 1 kΩ resistor, but with the 1 kΩ resistor the LEDs
would be slightly more dim.
PROGRAM FLOW
Fortunately, with the use of the BSHWB, coding for
circuits is simple. The BASIC Stamp Editor codes in
PBASIC, which is a simple and educational coding
language. It allows for the declaration of variables and
includes IF-ELSE statements and FOR Loops.
I coded this project as simply as possible. I tried to limit
variables and only used the HIGH/LOW command to
turn the LED’s on and off. There are more efficient ways
to structure and design this code, but because I was
working on a budget, I tried to make the design of the
code similar to the design of the circuit.
Using one continuous loop simulating a non-stop 24hour
cycle, a combination of IF-ELSE statements, and
one FOR Loop is used. The FOR Loop’s arguments
only apply to the variable used by the first row of the
minutes section, but all of the IF checks for the correct
time are made in both the infinite loop and the FOR
Loop. Nothing special went into efficiently keeping
track of the illuminated LEDs. I used four counters
for each row of LEDs. Each counter had a series of IF
statements associated with it in order to make sure the
correct LEDs were illuminated. The counters updated
at the end of each series of IF statements. Each LED
was then commanded to go High or Low depending on
what period of time it represented.
I set up my program to start from time zero every time.
This is not the way a clock should be setup. You are
rarely going to be starting this clock at midnight every
time you replace the battery. If you would like to add
functionality to this binary clock, increase the number
of available pins with a few demultiplexers and use
a potentiometer and an extra pushbutton to help with
setting the time.
FINAL DESIGN
Although there are some limitations with the BSHWB,
the potential for a full scale binary clock is available.
Actually there are ways to develop a binary clock
only using Flip-Flops and Gates. There are also other
microcontroller based circuit boards with more I/O pins
that can make development much easier. My particular
setup is shown below:
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