The PING))) sensors remain because they’re somewhat
of an integral part of this robot design. The only thing I
may change at some point is that the current PING)))
protector stands are aluminum, but the chassis is a smoke
translucent acrylic. There are acrylic PING))) stands available
from Parallax, however. I haven’t yet checked the height of
these stands, but for now they’re possible options for my
robot in the future. Okay, let’s get the current PING)))
sensors wired up. For this, I used three 10” three-pin F-F
(Female-Female) cables as show in Figure 9.
Be sure of the polarity of the connections on the pins
of the PING))) sensor. When looking at them from behind,
the pins are in this order: signal (white), power (red), and
ground (black). It can be easy to get them confused when
turned around — especially when mounted in the protector
stands because you can no longer see the pin designators.
Now, we can connect the power from the screw
terminals on the power pack into the motor driver board.
Be sure of the polarity! At this point, no option to switch
power for the motors has been implemented.
If you connect a 2.1 mm barrel plug into the charging
jack, it will cut power. So, this is an additional consideration
for revising the design. Next, run the PING))) cables up
through the hole in the upper deck, as well as the control
wires for the motor driver board. Once all the signal wires
are run, we can reconnect the upper and lower decks; refer
to Figure 10. On the Propeller project board, several three-pin headers will need to be installed to facilitate connecting
the sensors. In Figure 11, you can see the connections for
the wheel encoders, as well as the motor driver signals. The
sensors operate at 5V, so will need additional headers that
Finally, we need to add the second power pack. This is
the one that will power the control board. The Propeller
project board does not have a DC barrel jack, so we’ll
actually connect wires from the screw terminals to the VIN
tabs on the project board. This is another point where a
power switch is needed.
SERVO 07.2014 73
Figure 9. PING))) cables added.
Figure 10. Control/sensor wires routed under
the control board.
Figure 11. Control/sensor wires connected to the
header on the Propeller project board.
Figure 12. Mounting the second power pack,
inverted over the control board.