Published August 16, 2020 © GPL3+

Cold Storage Temperature Monitoring

The user is alerted through SMS alerts; LED and buzzer alarm is set off when temperature threshold is crossed

BeginnerFull instructions provided2 hours359

Things used in this project

Hardware components

Bolt IoT Bolt WiFi Module

USB-A to Mini-USB Cable

Breadboard (generic)

LED, Orange

Buzzer

Resistor 330 ohm

Male/Male Jumper Wires

Temperature Sensor

Copper Wire

Wire cutter and stripper

Software apps and online services

Bolt IoT Android App

Ubuntu

VMware Workstation 15 Player

Story

INTRODUCTION

This project continuously monitors the temperature in the cold storage facility with the help of LM35 temperature sensor. The operator sets a predefined threshold temperature value for the storage unit. The current values are displayed on the monitor with the help of Ubuntu software. If the threshold temperature is crossed, an SMS alert is sent to the operator along with the value of the current temperature reading of the storage unit. Also, visual and auditory cues are sent to the people nearby via lighting of an LED and the buzzing sound from the buzzer.

DEMONSTRATION

HARDWARE SETUP

The LM35 temperature sensor is at the heart of the Cold Storage Temperature Monitoring project. The steps to set up the hardware components of this project are given as follows:

Connect the LM35 to the breadboard
The Bolt WiFi module is connected to the LM35 temperature sensor through 3 male to male jumper wires.
Connect Vcc pin of LM35 to 5V pin of the Bolt WiFi module
Connect output pin of LM35 to Analog Input pin (A0) of the Bolt WiFi module
Finally, the ground pin of LM35 is connected to the ground pin (GND) of the Bolt WiFi module

LM35 pin configuration

Next, we have to connect an LED to the LM35 sensor. This is done by connecting the cathode (shorter leg) of the LED to the ground pin of the Bolt WiFi module via jumper wire and breadboard.
The anode (longer leg) of the LED is connected to a 330 ohms resistor (orange orange brown gold) in the breadboard

LED pin configuration

Connect jumper wire from resistor to digital pin 0 of the Bolt WiFi module
Connect buzzer to the breadboard. It's positive terminal (longer leg) is connected to the digital pin 1 of the Bolt WiFi module and the negative terminal (shorter leg) is connect to the GND pin of the Bolt WiFi module through jumper wires

Buzzer pin configuration

Lastly, we connect the Bolt WiFi module to the PC/laptop via a USB-A to Micro-USB cable

All set!

SOFTWARE SETUP

The code linked in below measures the temperature using the LM35 temperature sensor and thereafter sends it to the Bolt WiFi module over serial communication.
A Python Script (running on a server or your PC, for instance) queries the Bolt Cloud for this temperature value using the Bolt Python Library, which in turn is based on the Bolt open APIs.
The Python script then checks if the current temperature is less than a preset threshold temperature. In case the temperature exceeds the threshold value, an SMS alert is sent out using the Twillio SMS service.

SMS on the operator's phone

Code

Temperature Alert

import boltiot from Sms, Bolt  #Import Sms and Bolt class from boltiot library
import json, time  #Import json library to handle JSON objects and import time library 

threshold = 102   #store threshold value (approximately 10 degree celcius)

# Bolt credentials
API_KEY = 'Your Bolt Cloud API key'
DEVICE_ID = 'Your device ID'

# Credentials required to send SMS
SID = 'Your Twilio SID'
AUTH_TOKEN = 'Your Twilio auth token'
FROM_NUMBER = 'This is the no. generated by Twilio. You can find this on your Twilio Dashboard'
TO_NUMBER = 'This is your number. Make sure you are adding country code in the beginning'

mybolt = Bolt(API_KEY, DEVICE_ID) #Create object to fetch data
sms = Sms(SID, AUTH_TOKEN, TO_NUMBER, FROM_NUMBER) #Create object to send SMS

while True:   #Continuously monitor the temperature
  print("Reading sensor value")
  response = mybolt.analogRead('A0') #Read input from LM35 at A0 pin
  data = json.loads(response)        #load the JSON data sent by the cloud 
  sensor_value = int(data['value']) #store current temperature value in variable 
  temp = 100 * sensor_value / 1024    #covert into degree celcius
  print("Sensor value is: " + str(temp))  #print current temperature value
  mybolt.digitalWrite(0, 'LOW')  #Turn OFF LED connected at pin 0
  mybolt.digitalWrite(1, 'LOW') #Turn OFF buzzer at pin 1 
  try:
    sensor_value = int(data['value])
    if sensor_value > threshold: #checks if threshold has been crossed
      mybolt.digitalWrite(0, 'HIGH') #Turn ON LED at pin 0
      mybolt.digitalWrite(1, 'HIGH') #Turn ON buzzer at pin 1
      print("Making request to Twilio to send an SMS")
      response = sms.send_sms("ALERT! The temperature threshold has been exceeded! The current temperature is " + str(temp)) #Send SMS alert to operator
      print("Response received from Twilio is: " + str(response))#response from Twilio will be stored inside the `response` variable
      print("Status of SMS at Twilio is: " + str(response.status))
  except Exception as e:
    print("Error occured: Below are the details")
    print(e)
  time.sleep(10)  #Wait for 10 seconds

Credits

Akash Arun

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