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Digital Compass

This project is based on the Dinsmore 1490 Digital Compass

This sensor provides eight directions of heading information by measuring the earth's magnetic field using hall-effect technology. The 1490 sensor is internally designed to respond to directional change similar to a liquid filled compass. It will return to the indicated direction from a 90 degree displacement in approximately 2.5 seconds with no overswing. The 1490 can operate tilted up to 12 degrees with acceptable error. It is easily interfaced to digital circuitry and microprocessors using only pull-up resistors.
5-18 volts DC @ 30 ma
Open collector NPN, sink 25 ma per direction
2.25 grams
12.7 mm diameter, 16 mm tall
3 pins on 4 sides on .050 centers
-20 to +85 degrees C

The sensor magnetically indicates the four Cardinal (N. E, S. W) directions, and, by
overlapping the four Cardinal directions, shows the four intermediate (NE, NW, SE, SW) directions.
The sensor (Protected by patents and patents applied for) is a combination of a subminiature rotor
jewel suspended in combination with solid state Hall-effect IC's.
The sensor was designed to indicate the direction of the horizontal flux pattern (Compass component) of the
earth's field thus becoming a compass.
The sensor is damped to give the same speed indication as a liquid filled compass, that is, 0.5 second
response from 90º displacement without over-swing. It has built-in hysterisis to prevent indication "flutter"
when near a switching direction.
The sensor will accept input power between 6.0 and 18.0 volts, but should be polarity and ôspike"
protected from a vehicular power supply. The output is an "open collector NPN which will sink up to 25 mils
per direction.

Below is my finished PCB, and the PCB layout I used.


Below is a photo of my LED test PCB, I fabricated that to test the outputs of the sensor.

The OOPIC MCu, has a built in object for reading the Dinsmore 1490 Sensor called the oCompassDN,The oCompassDN Object uses the 4 I/O lines specified by the IOGroup and Nibble properties to read the Compass module. It converts the data to a URCP Heading value which is then stored in the Value property. See the OOPIC's manual for further information.

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