SERVO 11.2016 25
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even less expensive, but the 4WD chassis has roughly
twice the torque, and as such, can be used for
heavier more complicated robots.
Raspberry Pi 3 Model B
At the risk of sounding like a zombie, all I can
say at this point is brains ... I chose a Raspberry Pi 3
for Berry’s brains because:
1. It is inexpensive.
2. It is well supported.
3. It has onboard Wi-Fi.
4. It has onboard Blue Tooth.
5. It works well with RoboPi.
Later, I plan to add the new 8M pixel Pi camera. For
more information on the Raspberry Pi 3, you can check out
my review at www.mikronauts.com/raspberry-pi/
RoboPi Advanced Robot
Since Berry is supposed to be a smarter, more
advanced robot than Elf or Hobbit, I added my RoboPi
advanced robot controller. RoboPi has:
• An eight-core RISC coprocessor running at 100 MHz.
• An eight-channel 12-bit analog-to-digital converter
(ADC) with three-pin sensor headers.
• 24 “FlexIO” pins with servo-style headers; each
individual pin can be any of these:
1. Digital input
2. Digital output
3. PWM output
4. Servo output
5. Ping/HC-SR04 distance sensor input/output
For more information about the RoboPi, go to
L298N Driver Board
I wanted to be able to drive the four motors using only
a single dual H-bridge. The L293D motor driver used on Pi
Droid Alpha is not a good choice for driving two motors per
channel due to its maximum drive current per channel. For
those of you with Pi Droid Alphas or other L293D based
L293D — a lot of people use that approach to double the
current driving capabilities of L293D based motor driver
boards. Simply place a second L293D chip on the back of
the socketed chip, and tack-solder the legs together.
Your L298N board may look different than Photo 5.
PHOTO 3. Raspberry Pi 3 Model B.
PHOTO 4. RoboPi on top of Berry Bot.
PHOTO 5. L298N module on Berry Bot.