Arduino UNO Based Temperature Monitoring System with GSM Notification and Relay-Controlled Fan

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Circuit Documentation

Summary of the Circuit

This circuit integrates an Arduino UNO microcontroller with a SIM900A GSM module, a relay module, a temperature sensor (LM35), a fan, and power supply modules via micro USB to cable connectors. The Arduino UNO is used as the central processing unit to control the relay based on the temperature readings from the LM35 sensor and to communicate with the SIM900A GSM module. The relay controls the power to the fan, turning it on or off based on the temperature. The SIM900A module allows for GSM network communication, enabling potential features like remote monitoring or control via SMS or voice. The micro USB to cable connectors are used to provide power to the circuit components.

Component List

Arduino UNO

Microcontroller board based on the ATmega328P
Provides digital and analog I/O pins
Can be programmed via USB connection

SIM900A

GSM/GPRS module
Capable of sending SMS, making voice calls, and connecting to the internet
Interfaces with the Arduino via serial communication

Relay Module 5V-30V

Electromechanical switch that can be controlled by the Arduino
Used to turn the fan on and off
Has normally open (NO), normally closed (NC), and common contact (COM) terminals

Temperature Sensor (LM35)

Precision integrated-circuit temperature sensor
Outputs an analog voltage proportional to the temperature
Easy to interface with the Arduino analog input

Micro USB to Cable (2 Pin)

Power supply connector
Provides 5V power from a USB port to the circuit

Fan

5V DC fan
Used for cooling based on the temperature sensor reading

Wiring Details

Arduino UNO

5V connected to the relay module (normally open) and temperature sensor (LM35) +Vs
GND connected to the relay module (normally closed) and temperature sensor (LM35) GND
A0 connected to the temperature sensor (LM35) Vout
D11 connected to the SIM900A 5VR
D10 connected to the SIM900A 5VT
D7 connected to the relay module common contact

SIM900A

GND connected to the micro USB to cable connector -
5V connected to the micro USB to cable connector +
5VR connected to Arduino UNO D11
5VT connected to Arduino UNO D10

Relay Module 5V-30V

normally open connected to the temperature sensor (LM35) +Vs and Arduino UNO 5V
normally closed connected to Arduino UNO GND
common contact connected to Arduino UNO D7
trigger connected to the fan 5V and micro USB to cable connector +
V+ connected to the fan 5V and micro USB to cable connector +
V- connected to the fan GND and micro USB to cable connector -

Temperature Sensor (LM35)

+Vs connected to the relay module (normally open) and Arduino UNO 5V
Vout connected to Arduino UNO A0
GND connected to Arduino UNO GND

Micro USB to Cable (2 Pin)

+ connected to the SIM900A 5V, relay module V+, and fan 5V
- connected to the SIM900A GND, relay module V-, and fan GND

Fan

5V connected to the relay module trigger and V+
GND connected to the relay module V-

Documented Code

Arduino UNO Code (sketch.ino)

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

}

Note: The provided code is a template and does not contain any functional code. It needs to be populated with the logic for reading the temperature sensor, controlling the relay, and interfacing with the SIM900A module.