Theory Of Operation - Parallax 28044 Manual

The Centroid and Bounds radio buttons are used to choose how to mark the primary blob if one
is detected. The Centroid selection draws a red vertical line through the centroid (center of mass)
of the blob. The Bounds selection draws red vertical lines at the beginning and end locations (left
and right) of the blob.
The Pixels from Center text box displays the number of pixels the identified blob is away from the
center point of the frame. This value is used for range finding calculations.
The Slope and Intercept text boxes allow the user to enter specific values to affect range finding
calculations. The values will need to match those of the connected LRF Module in order for the
LRF Image Viewer to provide accurate range finding results. The "V" command can be used to
obtain the calibrated Slope and Intercept values of the LRF Module. The distance to the target
object is displayed in centimeters and inches in the Range text boxes.

Theory of Operation

This section describes advanced details of the LRF Module operation.
Program Structure
The source tree for the LRF Module consists of 4 custom designed objects and 7 objects either included
with the Parallax Propeller development environment or written by others and posted to the Parallax
Object Exchange (http://obex.parallax.com):
LRF_OVM7690.spin
│
├──LRF_con.spin
│
├──OVM7690_obj.spin
│ │
│ ├──LRF_con.spin
│ │
│ ├──OVM7690_fg.spin
│ │
│ │
│ │
│ ├──pasm_i2c_driver.spin
│ │
│ └──Synth.spin
│
├──JDCogSerial.spin
│
├──F32.spin
│
├──FloatString_Lite.spin
│ │
│ └──FloatMath_Lite.spin
│
└──Basic_I2C_Driver.spin
LRF_OVM7690.spin is the top object file. This object handles the user interface, command processing,
and laser range finding mathematics.
LRF_con.spin provides the global constants used throughout the program, including camera resolution,
blob detection, range finding, and calibration settings.
Copyright © Parallax Inc.
│
└──LRF_con.spin
Parallax Laser Range Finder (#28044) v1.0 9/16/2011 Page 14 of 24