Refrigerator monitor

One of the IoT use cases most people can relate to is refrigeration monitoring. All of us have refrigerators at home and it will really be nice to get an alert when the refrigerator’s temperature drops below a certain threshold. Then you can quickly take action on this alert and save your frozen goodies from going off.

Basic hardware, software and platform is not in the scope of this project and can be found at https://fastcomm.com/development-kit/

Material

Hardware

Aduino Uno
Hellothing L10 modem
Hellothing shield
A magnetic door sensor (or use the L10 push button to simulate a door)
A temperature sensor (LMT85LP)
Buzzer (or use the shield’s onboard LED to simulate an alert signal)

Steps process

Step 1:

Assemble hardware

Wire the sensors and door sensor as below:

Connect the temperature sensor’s negative pin to the ground (GND).

Connect the temperature sensor’s positive pin to the 5V supply.

Connect the temperature sensor’s data pin to pin A0 and give it a pullup resistor of 10k to 5V.

Connect the magnetic door sensor or test button to GND.

Connect the magnetic door sensor or test button to digital pin 2. This pin is set in software to have an internal pullup resistor.

 
                NBIoT *BG96_NBIoT = new NBIoT(EDGE);

BG96_NBIoT->setAPN("internet");

BG96_NBIoT->setOperator("65501");

NB-IoT is not covered as good as 2G yet, choose whether “EDGE” or “NB-IOT” will be used for this instance and ensure that your SIM correlates to this selection. Further, define the APN and operator:

Step 2:

Customise the software

Customise the software to comply with the required details as described in code box 1

char result[8];
dtostrf(BG96_NBIoT->getTemp(), 6, 2, result);
sprintf(input, "%s%s%s", "{"temp":"", result, "","door":"");
dtostrf(digitalRead(BUTTON), 1, 0, result);
strcat(input, result);
strcat(input, ""}");

Next the temperature and door magnetic sensor will be measured

Resources

https://github.com/Fastcomm/hellothing_NBIoT_Arduino_Shield
Download Resources