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April 2016 DocID028927 Rev 1 1/65
65
AN4825
Application note
Ultra-compact high-performance eCompass module
based on the LSM303AGR
Introduction
This document is intended to provide usage information and application hints related to ST's
eCompass module.
The LSM303AGR is a 3D digital magnetometer and 3D digital accelerometer system-in-
package with a digital I
2
C and 3-wire SPI interface standard output, performing at 250 μA in
combo high-resolution mode and no more than 60 μA in combo low-power mode. Thanks to
the ultra-low noise performance of the magnetometer and to the ultra-low power of the
accelerometer, the device combines always-on low-power features with superior sensing
precision for an optimal motion experience for the consumer. The device features ultra low-
power operational modes that allow advanced power saving and smart sleep-to-wake and
return-to-sleep functions.
The device has a magnetic field dynamic range of ±50 gauss and a user-selectable full-
scale acceleration range of ±2g/±4g/±8g/±16g.
The LSM303AGR can be configured to generate an interrupt signal for magnetic field
detection and to automatically compensate for hard-iron offsets provided from the higher
application layer. It can be configured to generate interrupt signals by detecting an
independent inertial wakeup/free-fall event as well as by the position of the device itself.
Thresholds and timing of the interrupt generator are programmable by the end user on the
fly. Automatic programmable sleep-to-wake-up and return-to-sleep functions are also
available for enhanced power saving.
The LSM303AGR has an integrated 32-level first in first out (FIFO) buffer allowing the user
to store accelerometer data in order to limit intervention by the host processor.
The LSM303AGR is available in a small thin plastic land grid array package (LGA) and it is
guaranteed to operate over an extended temperature range from -40 °C to +85 °C.
The ultra-small size and weight of the SMD package make it an ideal choice for handheld
portable applications such as smartphones, IoT connected devices, and wearables or any
other application where reduced package size and weight are required.
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