How to use H3LIS331DL 3-Axis arduino to detect Harsh braking

[rjrajbir]

Hi,
I am a newbie here, Recently I was working with H3LIS331DL 3-Axis Linear Accelerometer I²C Mini Module

Here is code for the X, Y, Z-axis.

#include <Wire.h>

// H3LIS331DL I2C address is 0x18(24)
#define Addr 0x18

void setup()
{
  // Initialise I2C communication as MASTER
  Wire.begin();
  // Initialise Serial Communication, set baud rate = 9600
  Serial.begin(9600);

  // Start I2C Transmission
  Wire.beginTransmission(Addr);
  // Select control register 1
  Wire.write(0x20);
  // Enable X, Y, Z axis, power on mode, data output rate 50Hz
  Wire.write(0x27);
  // Stop I2C Transmission
  Wire.endTransmission();

  // Start I2C Transmission
  Wire.beginTransmission(Addr);
  // Select control register 4
  Wire.write(0x23);
  // Set full scale, +/- 100g, continuous update
  Wire.write(0x00);
  // Stop I2C Transmission
  Wire.endTransmission();
  delay(300);
}

void loop()
{
  unsigned int data[6];
  for(int i = 0; i < 6; i++)
  {
    // Start I2C Transmission
    Wire.beginTransmission(Addr);
    // Select data register
    Wire.write((40+i));
    // Stop I2C Transmission
    Wire.endTransmission();

    // Request 1 byte of data
    Wire.requestFrom(Addr, 1);
    // Read 6 bytes of data
    // xAccl lsb, xAccl msb, yAccl lsb, yAccl msb, zAccl lsb, zAccl msb
    if(Wire.available() == 1)
    {
      data[i] = Wire.read();
    }
  }
  delay(300);

  // Convert the data
  int xAccl = ((data[1] * 256) + data[0]);
  int yAccl = ((data[3] * 256) + data[2]);
  int zAccl = ((data[5] * 256) + data[4]);

  // Output data to serial monitor
  Serial.print("Acceleration in X-Axis : ");
  Serial.println(xAccl);
  Serial.print("Acceleration in Y-Axis : ");
  Serial.println(yAccl);
  Serial.print("Acceleration in Z-Axis : ");
  Serial.println(zAccl);
  delay(300);
}

So my question is

how can I use this sensor to detect the harsh braking of the vehicle using Arduino nano?

[rproffitt]

Here's the research on that. Pick over priors at https://www.google.com/search?q=Arduino+Accelerometer%3A+detect+braking%2F+deceleration

1. You have to filter the input (some call this averaging.)
2. Since we can't be sure of orientation you implement the Pythagorean Theorem (such is on the web and appears to be taught in 9th grade so I won't write more about that.)