ADXL345 Digital 3-Axis Accelerometer

OVERVIEWER

The ADXL345 is a small, thin, low-power, 3-axis accelerometer with high resolution (13-bit) measurement up to ±16 g. Digital output data is formatted as a 16-bit two's complement and is accessible through either an SPI (3- or 4-wire) or I2C digital interface.

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 (3.9 mg/LSB) enables the measurement of inclination changes less than 1.0°.

Several special sensing functions are provided. Activity and inactivity sensing detect the presence or lack of motion and 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.

Figure 1: ADXL345 Functional Block Diagram

Technical Details:

ADXL345 3-Axis, ±2g / ±4g / ±8g / ±16g Digital Accelerometer

• Supply voltage range: 2.0V ~ 3.6V DC
• I/O voltage range: 1.7V to Vs
• Free-fall detection
• SPI (3- and 4-wire) and I2C digital serial interfaces
• Flexible interrupt modes mappable to either interface pin