accelerometer

In this article we connect an ADXL337 accelerometer to an Arduino Due

The ADXL337 is a small, thin, low power, complete 3-axis accelerometer with signal conditioned voltage outputs. The product measures acceleration with a minimum full-scale range of ±3g. It can measure the static acceleration of gravity in tiltsensing applications, as well as dynamic acceleration resulting from motion, shock, or vibration.

The user selects the bandwidth of the accelerometer using the C_X, C_Y, and C_Z capacitors at the X_OUT, Y_OUT, and Z_OUTpins. Bandwidths can be selected to suit the application, with a range of 0.5 Hz to 1600 Hz for X and Y axes, and a range of 0.5 Hz to 550 Hz for the Z axis.

Parts List

Schematic

arduino due and adxl337

Code

No libraries required – this is a sparkfun example

[codesyntax lang=”cpp”]

// Make sure these two variables are correct for your setup
int scale = 3; // 3 (±3g) for ADXL337, 200 (±200g) for ADXL377


void setup()
{
  // Initialize serial communication at 115200 baud
  Serial.begin(115200);
}

// Read, scale, and print accelerometer data
void loop()
{
  // Get raw accelerometer data for each axis
  int rawX = analogRead(A0);
  int rawY = analogRead(A1);
  int rawZ = analogRead(A2);
  
  // Scale accelerometer ADC readings into common units
  // Scale map depends on if using a 5V or 3.3V microcontroller
  float scaledX, scaledY, scaledZ; // Scaled values for each axis
  scaledX = mapf(rawX, 0, 675, -scale, scale); // 3.3/5 * 1023 =~ 675
  scaledY = mapf(rawY, 0, 675, -scale, scale);
  scaledZ = mapf(rawZ, 0, 675, -scale, scale);

  // Print out raw X,Y,Z accelerometer readings
  Serial.print("X: "); Serial.println(rawX);
  Serial.print("Y: "); Serial.println(rawY);
  Serial.print("Z: "); Serial.println(rawZ);
  Serial.println();
  
  // Print out scaled X,Y,Z accelerometer readings
  Serial.print("X: "); Serial.print(scaledX); Serial.println(" g");
  Serial.print("Y: "); Serial.print(scaledY); Serial.println(" g");
  Serial.print("Z: "); Serial.print(scaledZ); Serial.println(" g");
  Serial.println();
  
  delay(2000); // Minimum delay of 2 milliseconds between sensor reads (500 Hz)
}

// Same functionality as Arduino's standard map function, except using floats
float mapf(float x, float in_min, float in_max, float out_min, float out_max)
{
  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}

[/codesyntax]

Output

Open the serial monitor and you will see something like this

X: 612
Y: 500
Z: 554

X: 2.44 g
Y: 1.44 g
Z: 1.92 g

X: 619
Y: 478
Z: 510

X: 2.50 g
Y: 1.25 g
Z: 1.53 g

Links

https://www.analog.com/media/en/technical-documentation/data-sheets/ADXL337.pdf

The ADXL335 is a small, thin, low power, complete 3-axis accelerometer with signal conditioned voltage outputs. The product measures acceleration with a minimum full-scale range of ±3 g. It can measure the static acceleration of gravity

in tiltsensing applications, as well as dynamic acceleration resulting from motion, shock, or vibration.

The user selects the bandwidth of the accelerometer using the CX, CY, and CZ capacitors at the XOUT, YOUT, and ZOUT pins. Bandwidths can be selected to suit the application, with a range of 0.5 Hz to 1600 Hz for X and Y axes, and a range of 0.5 Hz to 550 Hz for the Z axis.

Here is a typical module that makes it easy to work with the ADXL335

Features:

Name: ADXL335 module (triaxial accelerometer analog output)
Model: GY-61
Power supply :3-5v
Analog X, Y, Z three-axis output

Schematic

The following layout shows how to wire the ADXL335 module up to an Arduino Due

arduino due and adxl335

Code

No libraries required for this example

[codesyntax lang=”cpp”]

const int xpin = A0; // x-axis of the accelerometer
const int ypin = A1; // y-axis
const int zpin = A2; // z-axis

void setup()
{
Serial.begin(9600);
}

void loop()
{
int x = analogRead(xpin); //read from xpin
delay(1); //
int y = analogRead(ypin); //read from ypin
delay(1); 
int z = analogRead(zpin); //read from zpin

float zero_G = 512.0; //ADC is 0~1023 the zero g output equal to Vs/2
float scale = 102.3; //ADXL335330 Sensitivity is 330mv/g
//330 * 1024/3.3/1000
Serial.print(((float)x - 331.5)/65*9.8); //print x value on serial monitor
Serial.print("\t");
Serial.print(((float)y - 329.5)/68.5*9.8); //print y value on serial monitor
Serial.print("\t");
Serial.print(((float)z - 340)/68*9.8); //print z value on serial monitor
Serial.print("\n");
delay(1000); //wait for 1 second 
}

[/codesyntax]

Output

Open the serial monitor and you should see something like this

83.00 86.34 85.61
88.28 77.76 76.67
90.69 75.47 74.36
90.54 75.32 74.51
35.20 12.95 21.04
36.41 15.09 21.91
29.48 11.23 19.17
43.50 15.24 18.74
19.52 2.79 34.59
35.51 14.09 22.77
35.66 14.24 22.48

Links

http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL335.pdf

The sensor costs under $2

GY-61 ADXL335 Module Triaxial Acceleration Gravity Angle Sensor