continued from page 7
Anyway, I "borrowed" your C LCD example of several
months ago as I originally had all the LCD stuff done in
Assembly on the GPS board. So, the display got moved to
the 18F board. I used Microchip C18 here and had to do
the port from Hi Tech. The nav PID is much easier to
implement in C ... originally, I was using a uM-FPU
coprocessor as needed for sin, cos, and atan functions but
that burned the I2C port back to the GPS board. Anyway, I
found the LCD shell really useful and have stripped it down
to the callable LCD functions. I had to add ISRs for the SPI,
TMR0, etc., but it’s working quite well! I'll most definitely
credit you for that code if I ever do an article.
I'm gonna modify the boat to use the Dynamixel servos
and control after reading your latest article. The old-style
PWM servos are a bit problematic as far as maintaining
resolution and eliminating jitter. I'll probably add a third
board to the design incorporating the Dynamixel stuff and
some "luxury" functions like lighting and control of a ham
BTW, the boat is a Dumas model "Mr. Darby" tugboat
— a massive twin screw platform I built about 15 years ago.
This project has been formulating for years and I'm finally
getting around to building the nav system. Thanks for the
ideas! I am a retired embedded programmer and enjoy
good code. It's good to see "hobby level" programming
really taking off.
Keep up the good work!
John, thanks for reading! It sounds like you are having
a bunch of fun on the water. I’m really happy to hear that
you could use some of the code and hardware from the
articles as that’s what it’s all about.
5 reflectance sensors on underside
The Pololu 3pi robot is a high-performance, compact
mobile platform featuring:
Two metal gearmotors
Five reflectance sensors
8×2 character LCD
Three user pushbuttons
Buzzer and LEDs
All peripherals are connected to an ATmega168
microcontroller running at 20 MHz, with free C-programming
tools, libraries, and support for the Arduino environment.
High-traction silicone tires
Speeds exceeding 3 ft/sec
using innovative constant-voltage motor supply
robot diameter is 3π cm (~ 3. 7 inches)
Find out more at www.pololu.com/3pi or by calling 1-877-7-POLOLU.
58 SERVO 05.2009