The Casio Pathfinder watch does more than just tell time and keep the date. It also includes a digital compass, which requires regular calibration to perform perfectly. The bidirectional calibration setting can be done in the field, and the northerly calibration requires a separate compass. Both are important in keeping the compass properly calibrated.
Enter the digital compass mode of the watch to begin bidirectional calibration. Bidirectional calibration should be used whenever you change environments significantly, as it improves the watch's ability to sense direction.
Press down the "A" button (the button on the upper left of the watch) until the display changes to the setting screen. The watch will be ready to sense the first direction.
Set the watch on a flat surface, facing any direction, and press the "B" button (the button on the upper right of the watch). This sets the primary direction.
Rotate the watch 180 degrees, then press the "B" button again. This will set the secondary direction. It is important that you turn the watch 180 degrees and select the direction opposite the primary direction.
Enter the digital compass mode of the watch to begin northerly calibration. This fully resets the internal compass within the watch and should be performed after a bidirectional calibration.
Press down the "A" button (the button on the upper left of the watch) until the display changes to the setting screen. Then Press down the "D" button (the button on the lower left of the watch) to enter the northerly calibration.
Set the watch on a flat and level surface, and move it so that the 12 o'clock position is pointed due north, as measured by a compass.
Press the "B" button (the button on the upper right of the watch) to set the watch compass. Allow the watch to complete the procedure before moving it. It will return to the digital compass screen when complete.
For specific instructions for each model of Pathfinder, see the Pathfinder manuals in the Resources section.
Make sure to perform the bidirectional calibration before the northerly calibration if you are performing both, as the bidirectional calibration will cancel previous northerly calibrations.