( www.oricomtech.com/projects/legs.htm). If you are
into legged robots, you have to see Dan’s site. You’d be
hard pressed to find as much good information regarding
legged robot gaits on a university site as
you will on Dan’s website! Anyway, you can
see this Pmod board in Figure 2 which is a
close-up shot of one of the two boards that
I used.
As I said, I’m using Arduino code here
to illustrate integration of hardware and
software to create a robot. So, in Listing 1,
I have the basic code setup to run six
servos from the board. I am using a Hobby
People 7.4V, 850 mAh lithium polymer
battery plugged directly into the MAX32
power jack through a homemade adapter
cable. This will power a 1A 5V regulator on
the board that we’ll use to power the
servos. The PIC32 is powered by a 3.3V
regulator which appears to use the 5V
regulator’s output as its input. The board
documentation warns that you should keep
the voltage under 9V to avoid overheating
the regulators if you decide to not use the
5V regulator (so you can put more voltage
to the servos). I just used 5V; it is good
enough to get everything working fine.
I’ll admit, my robot in Figure 3 doesn’t walk with this
example code, but it does a cool little dance! I built it by
using RC hobby servo tape (which is SUPER sticky double-sided adhesive tape) to stick the servos on to a 7 cm by 12
cm piece of 2 mm thick clear Lexan. I’m using nylon standoffs bolted to the board, and the Lexan to hold the rest
together. The battery is under the board.
The whole project weighs in at about 200 grams which
is less than half a pound. The wiring that I used came from
other project boards and various connectors from the junk
box – pointing out the value of a well-stocked junk box!
I did this project to create an experimental platform to
learn on and have fun with by the time we finish our
process here. Yes, even I will be learning something new
here since I have not programmed this part before.
The big question is will I use my trusty ICD3 (you can
also use a PICKit3 programmer) to program the board or
stick with the Arduino bootloader. It works with the Intel
hex file format that is the result of the Microchip C32
compiler, just like MPLAB would use. We can try both. It
would be weird, but workable to use; for instance, try
AVRdude in Arduino mode to download code via the USB
serial port to the MAX32.
Next month, we’re going to add a sonar and a Sharp
IR rangefinder to our robot to give it eyes. I’ll see what kind
of Pmod boards or perhaps Arduino shields we can use, as
well. Until then, stay tuned and check out the Digilent site
( www.digilentinc.com) for more cool chipKIT products
and add-ons.
As always, you can contact me at roboto@
servomagazine.com to ask me any question about robotics
that you have. I will do my level best to answer it! Until
then, keep building robots and sending me questions.
You’re never too old to learn new tricks! SV
Figure 3
16 SERVO 04.2012
