PNI SpacePoint Scout - Manual (Page 7)

PNI Sensor Corporation Doc #1017545 r03
SpacePoint Scout User Manual – January 2013 Page 7 of 19
4 Using the SpacePoint Scout
The SpacePoint Scout supports both UART and I
2
C interfaces for communicating with the user‟s
host system. These interfaces are discussed in Sections 4.2 and 4.3, respectively, which follow a
discussion on setting up the SpacePoint Scout.
PNI‟s CommBoard (pn 13466) can be mated with the SpacePoint Scout and this, in combination
with the SpacePoint Scout Test Program, provides a quick way to start working with the
SpacePoint Scout. See the PNI CommBoard User Manual and Section 6 for additional
information.
4.1 Setup
First, identify the arrowhead on the SpacePoint Scout PCB, then mount the Scout within the
host system such that the arrowhead points in the intended direction-of-travel or line-of-sight.
Figure 3-1 shows the pin-out. Note that TxD and RxD should be used for UART
communication, while SCL and SDA should be used for I
2
C communication. A couple of
points regarding mounting:
Mounting should be such that the SpacePoint Scout is isolated from persistent
accelerations, such as vibration or rapid directional changes. The Scout is intended to
provide accurate motion tracking while experiencing intermittent accelerations.
However, the Scout will have difficulty accurately tracking motion over extended
periods of time if it is constantly subjected to accelerations.
While the Scout can compensate for transient changes in the local magnetic field, it is
good design practice to keep the Scout away from sources of local magnetic
distortion that knowingly will change with time; such as speakers, electrical
equipment that will be turned on and off, or ferrous bodies that will move.
Finally, it is important to ensure the Scout is at rest when initially powered on, and remains at
rest for 3 seconds after powering on. The gyroscopes initialize during this period, and
movement of the module will distort the initialization process.
4.2 UART Communication
The SpacePoint Scout allows for communication with the host system via a UART interface.
Through the UART , the user‟s system requests the output from the SpacePoint Scout and the
module subsequently transmits this data. The outputs include quaternions, which prescribe