PNI SENtral - Manual (Page 9)

PNI Sensor Corporation Doc #1018049 R03
SENtral Technical Data Sheet Page 8
3 Layout
3.1 System Layout
Figure 3-1 provides a basic reference schematic for connecting SENtral with the host system
and the various sensors.
Figure 3-1: SENtral System Reference Schematic
A few points on system layout.

SENtral communicates with the sensors as the master via a dedicated I 2
C sensor bus.
The layout shows a discrete magnetometer, accelerometer, and gyroscope. SENtral
also works with combo sensors, such as a single 9-axis sensor or a combo gyro/accel
with a discrete magnetometer.

SENtral acts as a slave on the host system’s I
2
C bus. This does not need to be a
dedicated bus, although it is shown this way in the schematic. SA0 establishes
SENtral’s slave address when communicating with the host. It is shown set to
ground, but can be set HIGH instead. See Section 4.2.

The pull-up resistance on the I
2
C lines depends on the number of devices on the bus
and the bus speed. Normally 4.7 kΩ is appropriate for Standard or Fast modes (≤400
kbit/sec). See Section 4.4.

There are three dedicated sensor interrupt lines between the sensors and SENtral, and
one interrupt line between the host and SENtral. The default GPIO assignments are
shown, but these can be altered with the SENtral Configuration Tool. See Section 6.