28029 Parallax Inc, 28029 Datasheet - Page 140

• Manufacturer Part Number: 28029
• Description: KIT PARTS SMART SENSORS W/TEXT
• Manufacturer: Parallax Inc

Specifications of 28029

• Accessory Type: Parts Kit
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: BASIC Stamp® or Javelin Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant
• Other names: 28029PAR

Page 128 · Smart Sensors and Applications
module. With a mechanical compass, its bar magnet automatically lines up with north, so
you will instead have to move the compass module around the mechanical compass.
With this lesson in mind, make sure to keep mechanical compasses well away from the
compass module while performing and testing the calibrations in the next two activities.
ACTIVITY #2: COMPASS MODULE CALIBRATION
The calibration process involves pointing the compass module to known correct
directions as the calibration program is running. The calibration program will record the
values reported by the compass module into an unused portion of the BASIC Stamp's
EEPROM program memory. When you run the program in the next activity, it will read
these values from EEPROM and use them to determine the Compass Module's actual
heading. This is called “calibration in software” because the procedure does not make
any physical adjustments to the actual compass module.
Calibration Setup and Procedure
The setup involves aligning a compass printout and taping it to a flat surface. The
procedure involves running this activity's example program and following the prompts as
you align the Board of Education to the various spokes in the compass wheel.
Setup
√
√
Try it, and note how much distortion a nearby mechanical compass causes in the
compass module’s measurements.
Print or make a photocopy of Figure 4-7. If you are working from a printed copy
of the book and don't have a photocopier at your disposal, just download the .pdf
version of this text from the Smart Sensors and Applications product page at
www.parallax.com. Then, make a printout from that.