28029 Parallax Inc, 28029 Datasheet - Page 171

• 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

SUMMARY
The Hitachi HM55B Compass module is a dual-axis magnetic field sensor capable of
detecting microtesla variations in the components of the earth's magnetic field acting on
its x and y axes. The module's angle from north can be determined by dividing the x axis
measurement into the −y axis measurement, and then taking the arctangent of the result.
The compass module can also be used to detect magnetic fields from bar magnets as well
as the inclination of the earth's magnetic field at your locale.
The BASIC Stamp can store measured directions in the unused portion of its EEPROM
program memory with a calibration program. Then, a test program can access these
saved values, and use them to perform scale correction and linear interpolation on the
measurements.
measurement. By averaging the axis measurements, the direction measurement can be
further refined. The direction can be displayed in text format on the Parallax Serial LCD
by adding a small initialization routine to the program's Initialization section and a
SEROUT
Questions
1. What's the relationship between the compass module's x-axis measurement at a
2. What are the names of each of the compass module's pins that have to be
3. Which way does the angle from north increase in conventional compasses?
4. What's declination?
5. If you are measuring a magnetic field next to a bar magnet, how does the
6. Why can a nearby mechanical compass cause errors in the compass module's
7. How would you average twenty measurements?
8. What variables do you have to set to zero before averaging the x and y
9. What's the
10. If the number of digits in a displayed measurement might change, how do you
command to the program's main
given angle and the measurement when the x-axis is aligned with magnetic
north?
connected to BASIC Stamp I/O pins?
direction of the magnetic field relate to its N and S markings?
measurements?
measurements? Why do they have to be set to zero?
does it send?
prevent ghost characters from appearing at the right?
These correction techniques can significantly improve the direction
SEROUT
command for defining the degree symbol? How many bytes
DO
Chapter 4: Hitachi HM55B Compass Module · Page 159
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LOOP
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