interfacing memsic 2125 accelerometer

Development Boards Arduino
1

I am interfacing the Memsic 2125 accelerometer to the Arduino Pro Mini 5 V. I need to distinguish between the accelerometer being in the upright position and being upside down. As I rotated the accelerometer 180 degrees, the PulseIn values increased but then decreased back to the original upright value. I don’t understand why this is happening and if it is right.

here is my code that I got from a tutorial:

const int yPin = 5; // Y output of the accelerometer

// variables to read the pulse widths:

int pulseY;

void setup() {

// initialize serial communications:

Serial.begin(9600);

// initialize the pins connected to the accelerometer

// as inputs:

pinMode(yPin, INPUT);

}

void loop() {

// read pulse from y-axis:

pulseY = pulseIn(yPin,HIGH);

// print the acceleration

Serial.print(pulseY);

Serial.println();

delay(1000);

}

This is the y-axis output as I rotated it 180 degrees along the axis:

4972 //upright position

4976

5260

5531

5691

5864

6149

6208

6175

6134

6011

5885

5729

5608

5482

5402

5252

5087

4979

4972 //upside down

If this seems right, how can I distinguish between the accelerometer being upright and upside down?

Thank you.

2

saymyname,

My initial hunch, when I read your posting, was that you had started with the accelerometer Y axis horizontal and rotated it through vertical and back to horizontal.

In what direction did you rotate it, as described using the coordinates shown in the [“datasheet”? If you started with the pins vertical, then neither the X axis nor the Y axis should have been detecting gravity, because they are perpendicular to the pins.

I suggest you try other starting orientations and axes of rotation.

Happy Hunting,

Eric](http://www.parallax.com/Portals/0/Downloads/docs/prod/sens/28017-Memsic2Axis-v2.0.pdf)

3

Your initial hunch was correct! works now… :smiley: thank you very much for the insight.