to be connected without problems;
this header can also be used with
a standard IR sensor for remote
control. (I did this with the "rocket
man" prop — it was fun!)
Oh! Before I forget, there is
one final note on assembly: The
10K SIPs are intended to go on
the bottom side of the board
(Figure 5); this keeps them clear
of any wiring entering the
■ FIGURE 2.
Power 12 board.
■ FIGURE 3.
With 12 channels of control at our disposal and a
holiday season just begging for cool lighting projects, let's
jump right in — it's just a small matter of programming,
right? First up is a do-over of a BASIC Stamp program that
I wrote for my column four years ago: an electronic
With the BASIC Stamp version, we used a capacitor
on the output to smooth a random pulse to the LED to
[well, sort of] mimic the flame effect. With the power of
the Propeller, we don't need to do that any more, and we
can get more realism to boot. In the October ‘ 10 issue of
Nuts & Volts, there is an article that shows how to
simulate candle flames with the Propeller; we're going to
borrow some of that code and build the Menorah
program from it.
In the BASIC Stamp version, we simply turned it on
and it would light the candles for the current day (which
was incremented at each power-on cycle and stored in the
EEPROM). This meant that you had to light it on the first
day and not miss any days in between. For the update, I
wanted an easy way to select the day at random and to
allow manual control over lighting each "candle."
While watching my test LEDs flicker, I remembered a
program that I wrote in 1995 for a BASIC Stamp 1 user.
He was a pilot and owned a small airstrip. What he asked
me to create was a program that could count the number
■ FIGURE 5. VEX PPM stream.
of microphone "clicks" coming through his air-to-ground
radio system. The clicks count would be used to activate a
relay to turn on the runway lights. The idea was to look for
a specific number of clicks in a defined timeframe so that
standard radio communications would not trip the circuit.
In case you're wondering, yes, it worked. We used a
555 to one-shot the audio pulse which allowed the BASIC
Stamp 1 to detect it. With the Propeller, we can do the
same thing in software.
Since the Power 12 module has a button on it, this
seemed like a good way to go; we can start the sequence
(indicated by a lit Shamash candle) by pressing in the
current day (1 to 8), and then subsequent presses will light
the next candle. By using the secondary presses, the
ceremonial blessings can be recited between each candle.
(Please note: I am not Jewish and do not know if an
electronic Menorah is valid for the Hanukkah ceremony.
November 2010 15
■ FIGURE 4. TTL serial I/O.