PNI SpacePoint Scout - Manual (Page 13)

PNI Sensor Corporation Doc #1017545 r03
SpacePoint Scout User Manual – January 2013 Page 13 of 19
5.2 Cursor Position
The cursor position values, Hpos and Vpos, are used to map the SpacePoint Scout‟s
orientation to a cursor‟s position on a TV or computer screen.
Standard practice is for Hpos and Vpos values to range from –0.5 to +0.5, such that “0.0” is
the center of the screen, Hpos = –0.5 represents the left side of the screen, and Vpos = 0.5
represents the bottom of the screen.
The formulas in Table 5-1 show how to covert the raw Hpos and Vpos output to properly
scaled values, assuming a 16:9 screen ratio. Consequently, an ~60° rotation in the horizontal
plane will move the cursor from the left side of the screen to the right side, while an ~34°
rotation in the vertical plane will move the cursor from the top to the bottom of the screen.
Before using the position data, it is first necessary to set the SpacePoint Scout orientation
with respect to the screen. This is done by pointing the device at the center of the screen,
then sending the ResetRef command using either the UART or I
2
C interface.