Here’s another SparkFun breakout board, this time featuring the Analog Device ADXL345. This new version adds 2 standoff holes as well as an extra decoupling capacitor. The ADXL345 is a small, thin, low power, 3-axis accelerometer with high resolution (13-bit) measurement at up to ±16G. Digital output data is formatted as 16-bit twos complement and is accessible through either a SPI (3- or 4-wire) or I2C digital interface.

The ADXL345 is well suited to measures 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°.

So big deal – another accelerometer. Ah, but wait! This sensor has several built-in special functions:

• Detect activity and inactivity sensing
• Detect the presence or lack of motion
• Alert if the acceleration on any axis exceeds a user-set level. 
• Tap sensing detects single and double taps.
• Free-fall sensing detects if the device is falling. 

These functions can 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. Low power modes enable intelligent motion-based power management with threshold sensing and active acceleration measurement at extremely low power dissipation.

Features:

• 2.0-3.6VDC Supply Voltage
• Ultra Low Power: 40uA in measurement mode, 0.1uA in standby@ 2.5V
• Tap/Double Tap Detection
• Free-Fall Detection
• SPI and I2C interfaces