Please refer to Figure 2. The Arduino Uno
microcontroller is mounted in the small black dust cover
enclosure near the center of the figure. As most readers
will already be familiar with the Uno microcontroller
(except for unique project specific aspects), further
overview information will not be included here.
The plugboard (which can be seen in greater detail in
Figure 3) serves as a junction box for the various
component interconnections required. The white wire with
alligator clip connections leads to the solar cell taped to
an 8” x 12” piece of cardboard which is propped against a
sunny window pane above the workbench. A duplicate of
the window mounted solar cell is included in the photo.
The DVM (digital voltmeter) is not
required, but you should check to see
that your solar cell’s output stays under
the Arduino’s analog input max voltage
spec of 5 VDC when exposed to
maximum levels of sunlIght before
connecting it to the Uno. The
MakerPlot user interface runs on any
Windows based PC and will be
discussed further in the next section.
Component interconnections are very
simple (Figure 4). The 100 ohm load
resistor is not absolutely necessary, but
its presence will result in an overall
lower impedance circuit. We will
therefore gain higher noise immunity.
As mentioned, MakerPlot is a collection of
control components such as meters, switches,
The Arduino and the PC communicate using serial
ASCII data over the same USB cable link that is used by
the standard Arduino IDE to download a new program
into the microcontroller module. No physical cables need
to be switched to use MakerPlot; just be aware that you
can only do one of two tasks at a time: either display
MakerPlot app data or download code to the Arduino
This is the same constraint as when using just the
Arduino IDE; sharing the data link between program
downloads to the controller and displaying data on the
By Ken Fisher
FIGURE 3. Plugboard
Arduino Uno, and
duplicate of window
mounted solar cell.
FIGURE 2. A complete data acquisition system: an Arduino in the black
plastic enclosure and MakerPlot on the laptop. The wiring goes to the
solar cell in the window.
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August 2017 43
FIGURE 4. Wiring diagram.