介绍：
The ADXL345 is a small, thin, ultralow power, 3-axis accelerometerwith high resolution (13-bit) measurement at up to ±16 g. Digital output data is formatted as 16-bit twos complement（ 二进制补码) and is accessible（存取） through either a SPI (3- or 4-wire) or I2C digital interface.
The ADXL345 is well suited for mobile device applications. It measures the static acceleration of gravity in tilt-sensing (倾斜感应)applications, as well as dynamic acceleration resulting from motion or shock. Its high resolution (3.9 mg/LSB) enables measurement of inclination（倾斜） changes less than 1.0°.
Several special sensing functions are provided. Activity and inactivity sensing detect the presence（姿态） or lack of motion by comparing the acceleration on any axis with user-set thresholds. Tap（敲击） sensing detects single