Memsic 2125 Accelerometer

The Memsic 2125 (datasheet) is a two-axis accelerometer capable of measuring acceleration up to plus or minus 2g. It has a simple digital interface: two pins (one for each axis) emit pulses whose duration corresponds to the acceleration of that axis. By measuring the length of that pulse, in microseconds, using the pulseIn() function, it is possible to determine the rate of acceleration and to use that data for your purposes.

Hardware Required

  • Arduino or Genuino Board
  • Memsic 2125 Accelerometer
  • hook-up wires
  • breadboard


Use the small triangle on the Memsic to properly orient the sensor on your breadboard. Connect the 5V and GND pins of the Memsic 2125 to the power and ground ports on the board. Connect digital pin 2 of the board to the X out pin of the accelerometer, and digital pin 3 to the Y out pin.

Your Arduino or Genuino must be connected to your computer in order for it to transmit serial data.

click the image to enlarge

image developed using Fritzing. For more circuit examples, see the Fritzing project page


click the image to enlarge


Open the Serial Monitor of the Arduino Software (IDE) to see the values read from the accelerometer position.


   Read the Memsic 2125 two-axis accelerometer.  Converts the
   pulses output by the 2125 into milli-g's (1/1000 of earth's
   gravity) and prints them over the serial connection to the

   The circuit:
    * X output of accelerometer to digital pin 2
    * Y output of accelerometer to digital pin 3
    * +V of accelerometer to +5V
    * GND of accelerometer to ground

   created 6 Nov 2008
   by David A. Mellis
   modified 30 Aug 2011
   by Tom Igoe

   This example code is in the public domain.


// these constants won't change:
const int xPin = 2;     // X output of the accelerometer
const int yPin = 3;     // Y output of the accelerometer

void setup() {
  // initialize serial communications:
  // initialize the pins connected to the accelerometer
  // as inputs:
  pinMode(xPin, INPUT);
  pinMode(yPin, INPUT);

void loop() {
  // variables to read the pulse widths:
  int pulseX, pulseY;
  // variables to contain the resulting accelerations
  int accelerationX, accelerationY;

  // read pulse from x- and y-axes:
  pulseX = pulseIn(xPin, HIGH);
  pulseY = pulseIn(yPin, HIGH);

  // convert the pulse width into acceleration
  // accelerationX and accelerationY are in milli-g's:
  // earth's gravity is 1000 milli-g's, or 1g.
  accelerationX = ((pulseX / 10) - 500) * 8;
  accelerationY = ((pulseY / 10) - 500) * 8;

  // print the acceleration
  // print a tab character:


See Also

Last revision 2015/07/29 by SM