ET-MMA7331L (3-Axis Analog Output Accelerometer)

ET-MMA7331L

ET-MMA7331L

This sensor can give an output for accelerometer in 3-axis (X, Y, Z) with analog output. You can set g-force to measure as 4g or 12g and you can convert output from voltage to g unit by using this equation.

for Voffset is VDD/2 (VDD is power source voltage) and for sensitivity please use the value from this following table.

Table 1: Sensitivity and g-select

After you get Vout by using ADC then you can calculate back to get g-value for each channel (X, Y, Z)

Important: Voltage tolerant of this module is 3.6V, if you work on a 5V MCU please be careful

Sample Code:

//Accelerometer
#define X_OUT A8
#define Y_OUT A9
#define Z_OUT A10
#define Voffset 337 // 3.3/2 = 1.65v -> 1.65*1023/5 = 337.59
#define sensitivity 63 // 0.308 -> 0.308*1023/5 = 63.0168

float x_value = 0;
float y_value = 0;
float z_value = 0;

void setup() {
  //Accelerometer Initial
  pinMode(X_OUT, INPUT);
  pinMode(Y_OUT, INPUT);
  pinMode(Z_OUT, INPUT);
}

void loop() {
  // Read Accelerometer
  x_value = float(analogRead(X_OUT) - Voffset) / sensitivity;
  y_value = float(analogRead(Y_OUT) - Voffset) / sensitivity;
  z_value = float(analogRead(Z_OUT) - Voffset) / sensitivity;
  Serial.print("G x: ");
  Serial.print(x_value);
  Serial.print("G y: ");
  Serial.print(y_value);
  Serial.print("G z: ");
  Serial.println(z_value);
  delay(1000);
}

This program will read value from sensors and calculate g-value back and print out through serial port.

For pin configuration is Pin(6) Sleep = 1 , Pin(8) Self Test = 0 and Pin(7) g-Select you can choose according to table1

Pin Layout:

Reference: Datasheet