Circuit Documentation

Summary

This circuit integrates various components with an Arduino Nano to create a system capable of detecting impacts and providing location data. It includes a SIM800L module for GSM communication, a GPS NEO 6M module for location tracking, an ADXL335 accelerometer for impact detection, an LM2596 voltage regulator, a pushbutton for user input, and a buzzer for audio alerts. The Arduino Nano serves as the central processing unit, interfacing with the sensors and communication modules to detect impacts, acquire GPS coordinates, and communicate via SMS or voice call in case of an emergency.

Component List

Arduino Nano

• Microcontroller board based on the ATmega328P
• Provides digital and analog I/O pins
• Capable of serial communication via UART

SIM800L

• GSM/GPRS module
• Allows for SMS, voice calls, and data transmission
• Requires a power supply of 3.4V to 4.4V

ADXL335

• 3-axis accelerometer
• Measures acceleration with a minimum full-scale range of ±3 g
• Provides analog voltage output proportional to acceleration

GPS NEO 6M

• GPS module
• Provides location data including latitude and longitude
• Communicates with the microcontroller via UART

LM2596

• Voltage regulator module
• Steps down input voltage to a lower, regulated output voltage
• Used to power components requiring specific voltage levels

Pushbutton

• Momentary tactile switch
• Provides a digital input to the microcontroller

Buzzer

• Electromagnetic or piezoelectric sound-generating device
• Used for audible alerts or alarms

Wiring Details

Arduino Nano

• D2 connected to SIM800L RXD
• D3 connected to SIM800L TXD
• D5 connected to Buzzer PIN
• D6 connected to Pushbutton Pin 1 (in)
• D8 connected to GPS NEO 6M TX
• D9 connected to GPS NEO 6M RX
• GND connected to common ground net
• 5V connected to common VCC net
• A0 connected to ADXL335 X-OUT
• A1 connected to ADXL335 Y-OUT
• A2 connected to ADXL335 Z-OUT

SIM800L

• RXD connected to Arduino Nano D2
• TXD connected to Arduino Nano D3
• VCC connected to LM2596 OUT
• GND connected to common ground net

ADXL335

• VCC connected to common VCC net
• X-OUT connected to Arduino Nano A0
• Y-OUT connected to Arduino Nano A1
• Z-OUT connected to Arduino Nano A2
• GND connected to common ground net

GPS NEO 6M

• TX connected to Arduino Nano D8
• RX connected to Arduino Nano D9
• VCC connected to common VCC net
• GND connected to common ground net

LM2596

• IN connected to common ground net
• OUT connected to SIM800L VCC and GND

Pushbutton

• Pin 1 (in) connected to Arduino Nano D6
• Pin 3 (out) connected to common ground net

Buzzer

• PIN connected to Arduino Nano D5
• GND connected to common ground net

Documented Code

#include <AltSoftSerial.h>
#include <TinyGPS++.h>
#include <Wire.h>
#include <math.h>
#include <SoftwareSerial.h>

const String EMERGENCY_PHONE = "+918939843825";
#define rxPin 2
#define txPin 3

SoftwareSerial sim800(rxPin, txPin);
AltSoftSerial neogps;
TinyGPSPlus gps;
//RX Pin To D9
//TX Pin To D8

String sms_status, sender_number, received_date, msg;
String latitude, longitude;
#define BUZZER 5
#define BUTTON 6
#define xPin A0
#define yPin A1
#define zPin A2

byte updateflag;

int xaxis = 0, yaxis = 0, zaxis = 0;
int deltx = 0, delty = 0, deltz = 0;
int vibration = 2;
int devibrate = 75;
int magnitude = 0;
int sensitivity = 20;

double angle;
boolean impact_detected = false;
unsigned long time1;
unsigned long impact_time;
unsigned long alert_delay = 30000;

void setup()
{
  Serial.begin(9600);
  sim800.begin(9600);
  neogps.begin(9600);
  pinMode(BUZZER, OUTPUT);
  pinMode(BUTTON, INPUT_PULLUP);

  sms_status = "";
  sender_number = "";
  received_date = "";
  msg = "";
  sim800.println("AT");
  delay(1000);
  sim800.println("ATE1");
  delay(1000);
  sim800.println("AT+CPIN?");
  delay(1000);
  sim800.println("AT+CMGF=1");
  delay(1000);
  sim800.println("AT+CNMI=1,1,0,0,0");
  delay(1000);
  time1 = micros();
  xaxis = analogRead(xPin);
  yaxis = analogRead(yPin);
  zaxis = analogRead(zPin);
}

void loop()
{
  if (micros() - time1 > 4999) Impact();
  if (updateflag > 0)
  {
    updateflag = 0;
    Serial.println("Impact detected!!");
    Serial.print("Magnitude:");
    Serial.println(magnitude);

    getGps();
    digitalWrite(BUZZER, HIGH);
    impact_detected = true;
    impact_time = millis();
  }
  if (impact_detected == true)
  {
    if (millis() - impact_time >= alert_delay) {
      digitalWrite(BUZZER, LOW);
      makeCall();
      delay(1000);
      sendAlert();
      impact_detected = false;
      impact_time = 0;
    }
  }

  if (digitalRead(BUTTON) == LOW) {
    delay(200);
    digitalWrite(BUZZER, LOW);
    impact_detected = false;
    impact_time = 0;
  }
  while (sim800.available()) {
    parseData(sim800.readString());
  }
  while (Serial.available())  {
    sim800.println(Serial.readString());
  }
}

void Impact()
{
  time1 = micros();
  int oldx = xaxis;
  int oldy = yaxis;
  int oldz = zaxis;

  xaxis = analogRead(xPin);
  yaxis = analogRead(yPin);
  zaxis = analogRead(zPin);

  vibration--;
  Serial.print("Vibration = ");
  Serial.println(vibration);
  if (vibration < 0) vibration = 0;
  if (vibration > 0) return;
  deltx = xaxis - oldx;
  delty = yaxis - oldy;
  deltz = zaxis - oldz;

  magnitude = sqrt(sq(deltx) + sq(delty) + sq(deltz));
  if (magnitude >= sensitivity) //impact detected
  {
    updateflag = 1;
    vibration = devibrate;
  }
  else
  {
    magnitude = 0;
  }
}

void parseData(String buff) {
  Serial.println(buff);

  unsigned int len, index;
  index = buff.indexOf("\r");
  buff.remove(0, index + 2);
  buff.trim();
  if (buff != "OK") {
    index = buff.indexOf(":");
    String cmd = buff.substring(0, index);
    cmd.trim();

    buff.remove(0, index + 2);
    if (cmd == "+CMTI") {
      index = buff.indexOf(",");
      String temp = buff.substring(index + 1, buff.length());
      temp = "AT+CMGR=" + temp + "\r";
      sim800.println(temp);
    }
    else if (cmd == "+CMGR") {
      if (buff.indexOf(EMERGENCY_PHONE) > 1) {
        buff.toLowerCase();
        if (buff.indexOf("get gps") > 1) {
          getGps();
          String sms_data;
          sms_data = "GPS Location Data\r";
          sms_data += "http://maps.google.com/maps?q=loc:";
          sms_data += latitude + "," + longitude;

          sendSms(sms_data);
        }
      }
    }
  }
  else {
  }
}

void getGps()
{
  // Can take up to 60 seconds
  boolean newData = false;
  for (unsigned long start = millis(); millis() - start < 2000;) {
    while (neogps.available()) {
      if (gps.encode(neogps.read())) {
        newData = true;
        break;
      }
    }
  }

  if (newData)
  {
    latitude = String(gps.location.lat(), 6);
    longitude = String(gps.location.lng(), 6);
    newData = false;
  }
  else {
    Serial.println("No