Freescale MMA7455L数字加速度计方案

飞思卡尔(Freescale)公司的MMA7455L是小型低功耗±2g/±4g/±8g三轴数字输出加速度计,具有信号调理,低通滤波器,温度补偿,自测,以及可配置到检测0g或脉冲检测快速运动等功能,工作电压2.4V到3.6V,典型应用在手机,PMP,PDA,硬盘驱动(HDD),笔记本电脑,步程计和运动检测等.本文介绍了MMA7455L主要特性, 简化功能方框图, I2C接口到MCU的连接图与电路图以及SPI接口到MCU的连接图与电路图.

MMA745xL:±2g/±4g/±8g Three Axis Low-g Digital Output Accelerometer
The MMA7455L is a Digital Output (I2C/SPI), low power, low profile capacitive micromachined accelerometer featuring signal conditioning, a low pass filter, temperature compensation, self-test, configurable to detect 0g through interrupt pins (INT1 or INT2), and pulse detect for quick motion detection. 0g offset and sensitivity are factory set and require no external devices. The 0g offset can be customer calibrated using assigned 0g registers and g-Select which allows for command selection for 3 acceleration ranges
(2g/4g/8g). The MMA7455L includes a Standby Mode that makes it ideal for handheld battery powered electronics.

MMA7455L主要特性:
Digital Output (I2C/SPI)
3mm x 5mm x 1mm LGA-14 Package
Low Current Consumption
Self-Test for Z-Axis
Low Voltage Operation: 2.4 V – 3.6 V
User Assigned Registers for Offset Calibration
Programmable Threshold Interrupt Output
Level Detection for Motion Recognition (Shock, Vibration, Freefall)
Pulse Detection for Single or Double Pulse Recognition
Sensitivity (64 LSB/g @ 2g and @ 8g in 10-Bit Mode)
Selectable Sensitivity (±2g, ±4g, ±8g) for 8-bit Mode
Robust Design, High Shocks Survivability (5,000g)
RoHS Compliant
Environmentally Preferred Product
Low Cost

MMA7455L 典型应用:
Cell Phone/PMP/PDA: Image Stability, Text Scroll, Motion Dialing, Tap to Mute
HDD: Freefall Detection
Laptop PC: Freefall Detection, Anti-Theft
Pedometer
Motion Sensing, Event Recorder



图1.MMA7455L简化功能方框图



图2.MMA7455L I2C接口到MCU的连接图



图3.MMA7455L SPI接口到MCU的连接图



图4.MMA745xL评估板外形图



图5.MMA7455L I2C接口到MCU的连接电路图



图6.MMA7455L SPI接口到MCU的连接电路图