Luis Roda Sánchez
Published © GPL3+

Carfox: A Device to Find Them All

It makes your car smarter detecting accidents to help you where nobody can.

IntermediateFull instructions provided10 hours5,355
Carfox: A Device to Find Them All

Things used in this project

Hardware components

Arduino MKR Fox 1200
Arduino MKR Fox 1200
×1
SparkFun IMU Breakout - MPU-9250
SparkFun IMU Breakout - MPU-9250
×1
FlexiForce (Flexible force sensor)
×1
Buzzer
Buzzer
×1
Jumper wires (generic)
Jumper wires (generic)
×1
Resistor 100k ohm (generic)
×1
SparkFun Snappable Protoboard
SparkFun Snappable Protoboard
Any perforated protoboard
×1

Software apps and online services

Sigfox
Sigfox
Arduino IDE
Arduino IDE
Losant Platform
Losant Platform
Fusion 360
Autodesk Fusion 360

Hand tools and fabrication machines

Soldering iron (generic)
Soldering iron (generic)
3D Printer (generic)
3D Printer (generic)

Story

Read more

Custom parts and enclosures

Carfox cover

Schematics

Carfox implementation

Code

Carfox

Arduino
This piece of code was developed to send automatic alarm messages when a vehicle accident occurs via Sigfox using the Arduino MKR Fox 1200. The information sent is related to geolocation, temperature and the cause of the accident.
/* Carfox: a device to find them all
   by: Luis Roda Sánchez
   date: October 25, 2017
   Based on Kris Winer sketch for managing MPU-9250 and modified by Brent Wilkins.
   Sketch runs on the MKR FOX 1200.

  Hardware setup:
  MPU9250 Breakout --------- Arduino MKRFOX1200
  VDD ---------------------- VCC (3.3V)
  SDA ----------------------- 11
  SCL ----------------------- 12
  GND ---------------------- GND
*/

#include <SigFox.h>
#include "MPU9250.h"

boolean SerialDebug;  // Set to true to get Serial output for debugging.

// Pin definitions:
int buzzer  = 5;  // Set up pin 5 for buzzer.
int pressure = 0;
int pressurePin = A1;  // Set up analog pin 1 for pressure sensor.
int absAx = 900;
int absAy = 900;
int absAz = 900;
int freeFall = 900;
float temperature = 25;
boolean firstTime = true;

// Limits (adjusted for testing,
// they should be modified for real case):
int accelerationLimit = 3000;
int pressureLimit = 200;  // Around 25 kg.
int freeFallLimit = 300;
uint8_t highThreshold = 29;
uint8_t extremeThreshold = 32;
boolean holdHighTemperature = false;
boolean holdExtremeTemperature = false;

// Sigfox message structure:
typedef struct __attribute__ ((packed)) sigfox_message {
  uint8_t temperatureSigfox;
  uint8_t highTemp = 0;
  uint8_t extremeTemp = 0;
  uint8_t accident = 0;
  uint8_t criticalAccident = 0;
} SigfoxMessage;

// stub for message which will be sent
SigfoxMessage msg;

MPU9250 IMU;

void setup()
{
  Wire.begin();
  Serial.begin(115200);
  if (!SigFox.begin()) {
    // Something is really wrong, try rebooting
    // Reboot is useful if we are powering the board using an unreliable
    // power source (eg. solar panels or other energy harvesting methods).
    reboot();
  }

  // Send module to standby until we need to send a message.
  SigFox.end();
  SigFox.debug();

  SerialDebug = true; // Set to true to get Serial output for debugging.
  pinMode(buzzer, OUTPUT);

  // Read the WHO_AM_I register, this is a good test of communication.
  byte c = IMU.readByte(MPU9250_ADDRESS, WHO_AM_I_MPU9250);
  if (SerialDebug) {
    Serial.print("MPU9250 "); Serial.print("I AM "); Serial.print(c, HEX);
    Serial.print(" I should be "); Serial.println(0x71, HEX);
  }

  if (c == 0x71) // WHO_AM_I should always be 0x68.
  {
    if (SerialDebug) {
      Serial.println("MPU9250 is online...");
    }
    IMU.initMPU9250();
    // Initialize device for active mode read of accelerometer, gyroscope
    // and temperature.
    if (SerialDebug) {
      Serial.println("MPU9250 initialized for active data mode....");
    }
  } // if (c == 0x71)
}

void loop()
{
  if (IMU.readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01)
  {
    IMU.readAccelData(IMU.accelCount);  // Read the x/y/z accelerometer values.
    IMU.getAres();

    // Now we'll calculate the acceleration value into actual g's
    // This depends on scale being set, in this case the maximum range (+/- 16 g) (modified in library).
    IMU.ax = (float)IMU.accelCount[0] * IMU.aRes * 1000;
    IMU.ay = (float)IMU.accelCount[1] * IMU.aRes * 1000;
    IMU.az = (float)IMU.accelCount[2] * IMU.aRes * 1000;

    IMU.readGyroData(IMU.gyroCount);  // Read the x/y/z gyroscope values.
    IMU.getGres();

    // Calculate the gyro value into actual degrees per second
    // This depends on scale being set, in this case +/- 2000 DPS (modified in library).
    IMU.gx = (float)IMU.gyroCount[0] * IMU.gRes;
    IMU.gy = (float)IMU.gyroCount[1] * IMU.gRes;
    IMU.gz = (float)IMU.gyroCount[2] * IMU.gRes;

    pressure = analogRead(pressurePin);
    float pressureKgs = (float)pressure / 357 * 45.3592;

    IMU.tempCount = IMU.readTempData();  // Read the adc values.
    IMU.temperature = ((float) IMU.tempCount) / 333.87 + 21.0;

    if (SerialDebug) {
      // Pressure in kilograms.
      Serial.print("Pressure is ");
      Serial.print(pressureKgs);
      Serial.print(" kg");
      Serial.println();

      // Temperature in degrees Centigrade.
      Serial.print("Temperature is ");  Serial.print(IMU.temperature, 1);
      Serial.println(" degrees C");

      // Accelerations in mg.
      Serial.println("Accelerations:");
      Serial.print("X: "); Serial.print(IMU.ax);
      Serial.print(" mg ");
      Serial.print("Y: "); Serial.print(IMU.ay);
      Serial.print(" mg ");
      Serial.print("Z: "); Serial.print(IMU.az);
      Serial.println(" mg ");
      Serial.println();

      // Gyro values in degrees/sec.
      Serial.println("Gyro rates:");
      Serial.print("X: "); Serial.print(IMU.gx, 3);
      Serial.print(" degrees/sec ");
      Serial.print("Y: "); Serial.print(IMU.gy, 3);
      Serial.print(" degrees/sec ");
      Serial.print("Z: "); Serial.print(IMU.gz, 3);
      Serial.println(" degrees/sec");
      Serial.println();

      // Set alarms to false.
      msg.highTemp = 0;
      msg.extremeTemp = 0;
      msg.accident = 0;
      msg.criticalAccident = 0;
    } // if (SerialDebug)
  } // if (IMU.readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01)

  absAx = abs(IMU.ax);  // Absolute values.
  absAy = abs(IMU.ay);
  absAz = abs(IMU.az);

  msg.temperatureSigfox = (uint8_t)IMU.temperature; // Copy temperature to sigfox message.

  if (firstTime) { // Sending to refresh data at the beginning.
    firstTime = false;
    // Sending message via Sigfox.
    send2Sigfox();
  }

  if (msg.temperatureSigfox > highThreshold) {  // High Temperature.
    if (!holdHighTemperature) {  // To avoid sending repeated messages.
      holdExtremeTemperature = false;
      msg.highTemp = 1;
      holdHighTemperature = true;
      // Sending message via Sigfox.
      send2Sigfox();
    }
    else {
      if (msg.temperatureSigfox > extremeThreshold) {  // Extreme Temperature.
        if (!holdExtremeTemperature) {
          msg.extremeTemp = 1;
          holdExtremeTemperature = true;
          // Sending message via Sigfox.
          send2Sigfox();
          if (!SerialDebug) {
            do {
              delay(720000);  // Resend every 12 minutes.
              send2Sigfox();
            } while (1);
          }
        }
        else {
        }
      }
      else {
        if (msg.temperatureSigfox < (extremeThreshold - 1)) {  // Hysteresis to avoid errors and too many sendings.
          holdExtremeTemperature = false;
        }
      }
    }
  }
  else {
    if (msg.temperatureSigfox < (highThreshold - 1) && (holdHighTemperature == true || holdExtremeTemperature == true)) {  // Hysteresis to avoid errors and too many sendings.
      holdHighTemperature = false;
      holdExtremeTemperature = false;
      msg.highTemp = 0;
      msg.extremeTemp = 0;
      // Sending message via Sigfox to refresh data.
      send2Sigfox();
    }
  }

  if (absAx > accelerationLimit || absAy > accelerationLimit || absAz > accelerationLimit) {
    alarm(1);
  }
  if (IMU.az < 0) {
    alarm(4);
  }
  if (pressure > pressureLimit) {
    alarm(2);
  }
  freeFall = absAx + absAy + absAz;
  if (freeFall < freeFallLimit) {
    alarm(3);
  }
}

void alarm(unsigned char option) {  // Alarm goes off.
  int index = 9;
  switch (option) {
    case 1:
      if (SerialDebug) {
        Serial.println("ACCEL ALARM");
      }
      msg.accident = 1;
      send2Sigfox();
      do {
        analogWrite(buzzer, 50);
        delay(100);
        analogWrite(buzzer, 0);
        delay(200);
        if (SerialDebug) {
          index--;
        }
      } while (index > 7);
      break;

    case 2:
      if (SerialDebug) {
        Serial.println("PRESSURE ALARM");
      }
      msg.accident = 1;
      send2Sigfox();
      do {
        analogWrite(buzzer, 50); // Pin 5 to high.
        delay(300);
        analogWrite(buzzer, 0); // Pin 5 to low.
        delay(200);
        if (SerialDebug) {  // Infinite loop if a real case.
          index--;
        }
      } while (index > 6);
      break;

    case 3:
      if (SerialDebug) {
        Serial.println("FREEFALL ALARM");
      }
      msg.criticalAccident = 1;
      send2Sigfox();
      do {
        analogWrite(buzzer, 90);
        delay(100);
        analogWrite(buzzer, 0);
        delay(200);
        if (SerialDebug) {
          index--;
        }
      } while (index > 5);
      break;

    case 4:
      if (SerialDebug) {
        Serial.println("ROLL-OVER ALARM");
      }
      msg.criticalAccident = 1;
      send2Sigfox();
      do {
        analogWrite(buzzer, 50);
        delay(100);
        analogWrite(buzzer, 0);
        delay(200);
        if (SerialDebug) {
          index--;
        }
      } while (index > 2);
      break;
  }
}

void send2Sigfox() {
  // Start the module
  SigFox.begin();
  // Wait at least 30ms after first configuration (100ms before)
  delay(100);
  // Clear all pending interrupts
  SigFox.status();
  delay(1);
  SigFox.beginPacket();
  SigFox.write((uint8_t*)&msg, 5);
  SigFox.endPacket();
}

void reboot() {
  NVIC_SystemReset();
  while (1);
}

Credits

Luis Roda Sánchez

Luis Roda Sánchez

3 projects • 9 followers
IoT developer at the Albacete Reseach Institute of Informatics. Technology, electronics, science and sport.
Contact

Comments