Saturday, April 18, 2009

Infrared Distance Sensor with the Microcontroller Project

Infrared and Ultrasonic Scanner
(ATMEGA32 microcontroller)

This project is a short range, infrared and ultrasonic
scanner that uses a standard hobby servo to move the
sensors and a color LCD screen to display the information
from the distance sensors. The information displayed
on the LCD is an overhead view of the scanning area,
with increments of distance from the distance sensors.

Hardware Details:
The core of the project is the ATMEGA32 microcontroller
from Atmel. It controls the servo, gathers information from
the sensors and places the information on the LCD screen.
There is 32K of flash in the microcontroller and the software
uses about 13K of that. Since the LCD uses a maximum of
3.3V, the microcontroller is run at 3.3V.

Interfacing the GP2D02 to a Microcontroller PIC and
Sweeping it with a Hobby Servo

The Sharp GP2D02 is a sensitive compact distance measuring
sensor. It required two lines from a microcontroller in order to be
controlled. One line provides the signal to begin a measurement
and also is used to provide a clock signal when transmitting the
distance measure, and the other line is used to transmit the
measurements back to the microcontroller. I interfaced the GP2D02
to a 12CE519 microcontroller rather than my main CPU (16C77) in
order to free up processing time on the 16C77. The GP2D02 requires
an open collector on its input line, so I connected it through a diode
to the 12CE519. The GP2D02 output is connected directly to the
12CE519. As I was limited to one GP2D02 IR sensor per robot,
I used a hobby servo motor to sweep the GP2D02 through a 50
degree pattern in the front of the robot. The servo used was a
Cirrus CS-70 Standard Pro Servo.


The MBasic Compiler - DISTANCE SENSORS

There are many different types of technologies and devices
used in measuring distance, some of them being: Radar, Sonar,
Laser, Infrared and Ultrasonic. In this chapter Infrared and
Ultrasonic will be covered. Infrared uses light that is invisible to
the human eye. Also Infrared light bounces off almost everything.
Its main disadvantage is that fluorescent lights generate it and that
can cause interference. Ultrasonic uses sound that is inaudible to
the human ear. Its main advantage is that it is not sensitive to objects
of different colors and light reflecting properties. Its disadvantage
is that some materials absorb sound and don’t reflect it.

The components used in this project are one Sharp GP2D12
Infrared distance sensors, one Ultrasonic circuit, a buzzer, a rotary
switch circuit (refer to schematic from Project_5) also the parts from
Project_4. Fifteen of the twenty-two I/O pins of the PIC16F876 will
be used in this project.

Distance Sensor

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