Published March 30, 2020 © GPL3+

Smart Refrigerator Alert

This product alerts when a refrigerator door is opened

BeginnerFull instructions provided2 hours402

Things used in this project

Hardware components

Bolt IoT Bolt WiFi Module

DFRobot Gravity: Analog LM35 Temperature Sensor For Arduino

LED (generic)

Buzzer

Breadboard (generic)

USB-A to Micro-USB Cable

Software apps and online services

Bolt IoT Bolt Cloud

Bolt IoT Android App

Twilio SMS Messaging API

Story

LM35

The LM35 series are precision integrated-circuit temperature devices with an output voltage linearlyproportional to the Centigrade temperature. The LM35 device has an advantage over linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a large constant voltage from the output to obtain convenient Centigrade scaling.

The LM35 device does not require any external calibration or trimming to provide typical accuracies of ±¼°C at room temperature and ±¾°C over a full −55°C to 150°C temperature range. Lower cost is assured by trimming and calibration at the wafer level. The low-output impedance, linear output, and precise inherent calibration of the LM35 device makes interfacing to readout or control circuitry especially easy. The device is used with single power supplies, or with plus and minus supplies.

As the LM35 device draws only 60 μA from the supply, it has very low self-heating of less than 0.1°C in still air. The LM35 device is rated to operate over a −55°C to 150°C temperature range, while the LM35C device is rated for a −40°C to 110°C range (−10° with improved accuracy). The LM35-series devices are available packaged in hermetic TO transistor packages, while the LM35C, LM35CA, and LM35D devices are available in the plastic TO-92 transistor package.

The LM35D device is available in an 8-lead surface-mount small-outline package and a plastic TO-220 package.

LM35 pin configuration

Pin Configuration:

Vs - Supply voltage

Vout - Output

GND - Ground

STEPS to do this project:

Do the connections of the circuit as shown below
Create a product on the Bolt Cloud (https://cloud.boltiot.com/home)
Select the code option, type the code and save it with javascript (.js) extension
Link the product with your Bolt device
You can type your python code either in Digital Ocean (https://cloud.digitalocean.com/login) or in the Oracle VM Virtual Box (https://www.virtualbox.org/wiki/Downloads) ubuntu server (http://releases.ubuntu.com/16.04/ubuntu-16.04.6-server-i386.iso)
In the ubuntu server, type your python code with suitable file name and extension.py or copy the code given
Connect the Bolt module to power supply and run the python code

Code

import conf, requests, math, time, json
from boltiot import Sms, bolt

value1 = 13.5
value2 = 15

mybolt = Bolt(conf.API_KEY, conf.DEVICE_ID)
sms = Sms(conf.SID, conf.AUTH_TOKEN, conf.TO_NUMBER, conf.FROM_NUMBER)
mybolt.digitalWrite(0,"LOW")
mybolt.digitalWrite(2,"LOW")

while True:
    print("Reading Sensor Value")
    response = mybolt.analogRead('A0')
    data = json.loads(response)
    print("Sensor value is " + str(data['value']))
    try:
        sensor_value = int(data['value'])
        if sensor_value < value2 or sensor_value > value1:
            mybolt.digitalWrite(0,"LOW")
            mybolt.digitalWrite(2,"HIGH") 
        elif sensor_value > value2 or sensor_value < value1:
            print("Making request to TWILIO to send SMS")
            temp=((100*sensor_value)/1024)
            response = sms.send_sms("Someone has opened the fridge. The current temperature in fridge is: " +str(temp))
            print("Response recieved from TWILIO is: " +str(response_status))
            mybolt.digitalWrite(0,"HIGH")
            mybolt.digitalWrite(2,"LOW")
    except Exception as e:
        print("Error")
        print(e)
    time.sleep(10)

Credits

Shreyas B V

4 projects • 7 followers

Smart Refrigerator Alert

Things used in this project

Hardware components

Software apps and online services

Story

Schematics

Circuit Diagram

Code

Python code

Configuration code

javascript code

Credits

Shreyas B V

Comments

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Smart Refrigerator Alert

Smart Refrigerator Alert

Things used in this project

Hardware components

Software apps and online services

Story

Schematics

Circuit Diagram

Code

Python code

Configuration code

javascript code

Credits

Shreyas B V

Comments

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