ElectronicComponent

MMA8451 3-Axis Accelerometer

MMA8451 3-axis Accelerometer

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Description

The MMA8451 Accelerometer measures the acceleration in 3-axes, has a resolution of 14-bit and can measure +/-2g, +/-4g or +/-8g, depending on your desired accuracy (where 1 g denotes acceleration due to gravity).

The chip itself is manufactured by Freescale Semiconductor and is a surface mount component that measures 3.0x3.0x1.0mm. Adafruit and Sparkfun distribute a breakout board kit, which will ease the trouble of interfacing with this chip.

Pinout

Adafruit sells a breakout board kit, which comes with a onboard power regulator. The Adafruit breakout board comes with 8 pins:

  • Vin Powers the board, accepts 3-5 Volt DC and should be the same level as the logic level.
  • GND Common ground connection pin.
  • 3vo The Adafruit board comes with an onboard voltage regulator. This pin outputs 3.3V at maximum 100mA so you can power something else, within those limits.
  • I2.
  • I1.
  • SCL I2C clock pin, which can safely be used with 3V and 5V logic.
  • SDA I2C data pin, which can safely be used with 3V and 5V logic.
  • A this pin is used to select the I2C address. By default the address is '0x1C' and this pin is pulled-down to 0V via a 10 kΩ resistor. The address can be changed to '0x1D', by connecting it to the 3vo line

Wiring Notes

  1. Arduino Power the board from the 5V pin. Connect the SDA and the SCL pin to the Analog A4 and A5 pins, respectively. See tutorial here.
  2. Raspberry Pi People have encountered problems with running this board with the Raspberry Pi, which comes from the "repeated start" command for the I2C connection. Anything is possible and I am sure that somebody has figured out a work-around somewhere.
  3. MSP430 Launchpad Power the board from the 3.3 Volt pin. Connect the SDA and SCL pins on the RTC to the SDA and SCL pins on the Launchpad board, respectively. You will need to add 1.8kΩ pull-up resistors to the SDA and SCL pins. See tutorial here.
    • MSP430F5529 Connect SDA -> P3.0 and SCL -> P3.1

Quick Overview

 MMA8451 Accelerometer
Input Voltage3-5V
Current Consumption6 μA to 165 μA
Sensing Range Modes+/- 2g, +/-4g, +/-8g
Resolution8-bit and 14-bit
Output Data Rates1.56 Hz - 800 Hz
Operating Temperature-40 C to +85 C
I2C Address0x1C (default)
0x1D (with A pin at 3V)
Price surface-mount IC$1.67 here
Price Breakout Board$8.52 here

Related Tutorials

Arduino.MMA8451Arduino

MMA8451 Accelerometer on the Arduino UNO
Setup the MMA8451 Accelerometer with the MSP430 Launchpad and Energia.

MSP430LaunchPad.MMA8451Energia

MMA8451 Accelerometer on the Launchpad with Energia
Setup the MMA8451 Accelerometer with the MSP430 Launchpad and Energia.

External Links

  1. Manufacturer Data Sheet
  2. Adafruit Breakout Board Info