Freescale公司的MMA845xQ系列是智能低功耗三軸容性微機械加速度計,具有12位分辨率,電源電壓1.95V-3.6V,接口電壓1.6V-3.6V,動態可選擇滿刻度+/-2g/+/-4g/+/-8g,輸出數據速率(ODR)為1.56 Hz 到800 Hz,12位和8位數字輸出,I2C數字輸出接口,電流消耗6uA-160uA,主要用于電子羅盤,靜態方向檢測,筆記本,電子書等跌落檢測,實時方向檢測和工作分析,手持設備運動檢測,震動和振動監視和用戶接口.本文介紹了MMA845xQ系列主要特性和方框圖,應用框圖以及MMA845xQ加速計開發套件LFSTBEB845x電路圖與MMA8451/2/3Q應用電路圖.

The MMA8452Q is a smart low-power, three-axis, capacitive micromachined accelerometer with 12 bits of resolution. This accelerometer is packed with embedded functions with flexible user programmable options, configurable to two interrupt pins. Embedded interrupt functions allow for overall power savings relieving the host processor from continuously polling data.

The MMA8452Q has user selectable full scales of +/-2g/+/-4g/+/-8g with high-pass filter filtered data as well as non-filtered data available real-time. The device can be configured to generate inertial wakeup interrupt signals from any combination of the configurable embedded functions allowing the MMA8452Q to monitor events and remain in a low power mode during periods of inactivity. The MMA8452Q is available in a 3 mm by 3 mm by 1 mm QFN package.

MMA845xQ系列主要特性:

. 1.95V to 3.6V supply voltage

. 1.6V to 3.6V interface voltage

. +/-2g/+/-4g/+/-8g dynamically selectable full-scale

. Output Data Rates (ODR) from 1.56 Hz to 800 Hz

. 99 ug/√Hz noise

. 12-bit and 8-bit digital output

. I2C digital output interface

. Two programmable interrupt pins for six interrupt sources

. Three embedded channels of motion detection

. Freefall or Motion Detection: 1 channel

. Pulse Detection: 1 channel

. Transient Detection: 1 channel

. Orientation (Portrait/Landscape) detection with set hysteresis

. Automatic ODR change for Auto-WAKE and return to SLEEP

. High-Pass Filter Data available real-time

. Self-Test

. RoHS compliant

. Current Consumption: 6uA-165 uA

MMA845xQ系列典型應用:

. eCompass applications

. Static orientation detection (Portrait/Landscape, Up/Down, Left/Right, Back/Front position identification)

. Notebook, eReader and Laptop Tumble and Freefall Detection

. Real-time orientation detection (virtual reality and gaming 3D user position feedback)

. Real-time activity analysis (pedometer step counting, freefall drop detection for HDD, dead-reckoning GPS backup)

. Motion detection for portable product power saving (Auto-SLEEP and Auto-WAKE for cell phone, PDA, GPS, gaming)

. Shock and vibration monitoring (mechatronic compensation, shipping and warranty usage logging)

. User interface (menu scrolling by orientation change, pulse detection for button replacement)


圖1.MMA845xQ系列框圖

圖2.MMA845xQ系列應用框圖

MMA845xQ加速計開發套件

The Freescale MMA845xQ sensor toolbox accelerometer kit provides hardware and software for development and demonstration of the MMA845xQ family of accelerometers.

MMA845xQ加速計開發套件包括:

The kit includes the following:

• MMA845xQ evaluation board

• MMA8451Q accelerometer daughter board

• MMA8452Q accelerometer daughter board

• MMA8453Q accelerometer daughter board

The kit requires the LFSTBUSB USB-interface board to attach the kit to a personal computer. If you already have the RD3924MM450Q Sensor Toolbox, for the MMA8450Q accelerometer, the USB board is in that kit.

The MMA845xQ kit’s part number is LFSTBEB845x and the USB-interface board’s part number is LFSTBUSB.

圖3.MMA845xQ加速計開發套件外形圖


圖4.LFSTBEB845x電路圖(1)

圖5.LFSTBEB845x電路圖(2)


圖6.LFSTBEB845x開發板布局圖

圖7.MMA8451Q電路圖

圖8.MMA8452Q電路圖

圖9.MMA8453Q電路圖
詳情請見:
http://cache.freescale.com/files/sensors/doc/data_sheet/MMA8452Q.pdf?fpsp=1&WT_TYPE=Data
Sheets&WT_VENDOR=FREESCALE&WT_FILE_FORMAT=pdf&WT_ASSET=Documentation
和
http://cache.freescale.com/files/sensors/doc/user_guide/MMA845xQSTUG.pdf
以及
http://cache.freescale.com/files/sensors/doc/support_info/LFSTBEB845x__SCH.pdf