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H: Display available commands
Lists all available commands that the LRF Module supports.
Terminal Example:
:H
Basic Commands:
R
Single range measurement
B
Single range measurement (binary response, 2 bytes)
L
Repeated range measurement (any subsequent byte will stop the loop)
<more commands listed, but not shown in this manual>
:
O: Display coordinate, mass, and centroid information for all detected blobs
Displays coordinate, mass, and centroid (center of mass) information for up to 6 detected blobs within
the camera's field-of-view. This information can be used for custom image processing or object detection
outside of the standard LRF Module functionality. The blob detection begins on the left side of the frame
and "scans" to the right. See Image Processing and Blob Detection, page 20, for details.
L: X coordinate of the beginning (left side) of the detected blob
R: X coordinate of the end (right side) of the detected blob
M: Mass of blob (sum of all valid pixels within the blob)
C: Centroid (center of mass) of blob
<: Marker to indicate if the blob is less than the BLOB_MASS_THRESHOLD
*: Marker to indicate the blob with the largest mass (primary blob)
In many cases, if a single blob is detected within the frame, it is likely the laser spot. In other cases,
there may be reflections of the laser light or other spots that are not related to the laser. Generally, the
blob with the largest mass within the frame can be considered the actual laser spot.
Terminal Example:
:O
0: L = 81 R = 88 M = 14 C = 84 <
1: L = 137 R = 232 M = 917 C = 181 *
2: L = 235 R = 254 M = 170 C = 244
:
X: Calibrate camera system for range finding
To account for manufacturing and assembly variances, particularly related to the camera and laser diode
alignments, each LRF Module must be calibrated. This occurs during production, but the LRF can be re-
calibrated by the user at a later date if desired. If a new major version of firmware is loaded (for
example, upgrading from firmware version 1.0 to 2.0), the LRF will need to be re-calibrated.
The calibration routine requires the user to place the LRF Module at 6 fixed distances (from 20 cm to 70
cm at 10 cm intervals), measured from the front face of the LRF circuit board. The LRF takes
measurements at each distance and calculates the SLOPE, INTERCEPT, and PFC_MIN values. The values
are then stored in an unused portion of the non-volatile boot Serial EEPROM. They will remain intact
during a power cycle.
Copyright © Parallax Inc.
Parallax Laser Range Finder (#28044)
v2.0 10/31/2015 Page 7 of 23
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