ADXL345 Hookup Guide

Contributors: TheDarkSaint

Hardware Overview

Features

• Supply Voltage: 2.0 - 3.6 VDC
• Ultra Low Power: As low as 23 uA in measurement mode, 0.1uA in standby mode at 2.5V
• SPI or I2C Communication
• Single Tap / Double Tap Detection
• Activity / Inactivity Sensing
• Free-Fall Detection

Whoa! What are those last three?! Yes, the ADXL345 has special sensing abilities! The single and double tap sensing detects when a single, or two simultaneous, acceleration events occur. Activity and inactivity sensing detect the presence or lack of motion. Free-fall sensing compares the acceleration on all axes with the threshold value to know if the device is falling. All thresholds levels that trigger the activity, free-fall, and single tap/double tap events are user-set levels. These functions can also be mapped to one of two interrupt output pins. An integrated, patent pending 32-level first in, first out (FIFO) buffer can be used to store data to minimize host processor intervention.

The ADXL345 is well suited to measure the static acceleration of gravity in tilt-sensing applications, as well as dynamic acceleration resulting from motion or shock. Its high resolution (4 mg/LSB) enables measurement of inclination changes less than 1.0°. Furthermore, low power modes enable intelligent motion-based power management with threshold sensing and active acceleration measurement at extremely low power dissipation.

Applications

• Handsets
• Medical Instrumentation
• Gaming and Pointing Devices
• Industrial Instrumentation
• Personal Navigation Devices
• Hard Disk Drive (HDD) protection

Pin Functionality

Below you can reference the ADXL345 breakout board and pin functions.

Breakout Board Pin Function Descriptions