BikePin

The way the components are organised is that the Arduino mini Pro is the brains of the operation, the battery is the heart that keeps everything running and other modules keep it functioning the way they are suppose to. 

A boost voltage regulator is also used because the SIM800L needs 5V 

Added new script to the existing repository: New source code

Serial.print("Now, entering SMS content: ");
  char str1[16];
  char str2[16];
  dtostrf(gps.location.lat(), 10, 6, str1);
  dtostrf(gps.location.lng(), 10, 6, str2);

  char str3[4]= ",";
  char str [160] = "https://www.google.com/maps/place/";
  strcat(str, str1);
  strcat(str, str3);
  strcat(str, str2);

This is the content that is sent and also displayed on the other side.

bool RTCinit(uint8_t interruptPin, function_ptr alarmISR);
time_t RTCsetNewTime(time_t dataTime);
void RTCsleepNow();
void RTCprint(time_t t);
time_t RTCsetNextAlarm(uint16_t sleepPeriod);

Declaration of RTC functions that are crucial for maintaining the work flow of the device and keeping it up and running only when needed 

That is where the key word come in hand and in this case it is set to "GPS"

char x[15]="GPS";
if (sms.available()) {
    Serial.println("Message received from:");
    sms.remoteNumber(senderNumber, 20);}

Adding update and more functions to the existing BikePin web app on which all data representation and history will be based. 

Client, by sending the key word message to the device, will be given the location and also that same location will be stored in his account on the app.

For a local incubator business incubator competition, a modified version of the BikePin device was created which included a 18650 battery, Wemos D1 mini, GN-801 GPS module and a SIM800L GSM module.
Device's functionality is based on MQTT protocol to which a key word is sent and only then a device responds to the sender with its exact location.
GitHub repository