le of Contents
Table of Tables 2
Table of Figures 2
1. Introduction 3
2. Research Survey 4
2.1. Smart Home Systems 4
2.1.1. Apple HomeKit 4
2.1.2. Amazon Echo & Alexa 4
2.2. Smart Home Device 5
2.2.1. Philips Hue 5
2.2.2. Tado Smart Thermostat 5
3. Block Diagram 7
4. Components and Descriptions 8
4.1. Global System for Mobile communication (GSM Modem) 8
4.2. Light Dependent Resistor (LDR) 9
4.3. Light-Emitting Diode (LED) 9
4.4. Temperature Sensor 10
4.5. Smoke Sensor 10
5. Logic Gates 11
5.1. AND Gate 11
5.2. OR Gate 11
5.3. XOR Gate 11
5.4. NOT Gate 12
6. Simple Electronic Design Circuit 12
7. Circuit Design Description 14
7.1. CEDAR Logic for Fire Sprinkler System and Fan & AC 15
7.2. CEDAR Logic for Curtain & Lighting 17
8. Final Flowchart 20
9. Final Truth Table 21
10. Final Circuit 21
11. Unresolved Problems 22
12. Assumptions 22
13. Conclusion 22
14. References 22
Table of Tables
Table 1: Truth Table for AND Gate 11
Table 2: Truth Table for OR Gate 11
Table 3: Truth Table for XOR Gate 11
Table 4: Truth Table for OR Gate 12
Table 5: Final Truth Table for final circuit 21
Table of Figures
Figure 1:Block Diagram 8
Figure 2: Pinout SIM900 9
Figure 3: SIM900 GSM Quadband Module for Raspberry Pi 9
Figure 4: Light Dependent Resistor (LDR) 10
Figure 5: Light-Emitting Diodes (LED) 10
Figure 6: Temperature Sensor LM35 11
Figure 7: Smoke Sensor (MQ-2) 11
Figure 8: IoT Based Temperature Monitoring 13
Figure 9: Circuit of the smart bulb holder 14
Figure 10: Design Outline 15
Figure 11: Final Flow Chart 21
Figure 13: Final Circuit 22
Introduction
The world we live in today has been gradually replaced by automations where many of the systems are getting automated and no longer require human to make it happen manually. This includes home, industrial, production, business automation and many more.
Home automation systems, also more commonly known as ‘smart house’, are advancement of mechanization processes of human effort where access is provided to control and operate devices located in house remotely. This involves IoT appliances such as lightings, electronic devices like microwaves or kettle where users may switch it on ahead of time before reaching home to reduce the total amount of waiting time and spent it wisely. From a home security perspective, users are able to monitor and assured that their house is perfectly safe from any type of harm with the convenience of monitoring and accessing its system anytime while being away from home, which includes alarms, buzzers, gates, surveillance camera.
Our home automation systems are aimed at lightening up the load of modern-day people with utmost convenience as their pace are getting busier and busier day by day. The systems connected to microcontroller & WIFI for centralized remote control and implemented with threshold that will set off limit, which automatically provides more comfort for people with least amount of effort, example, when the temperature exceeded the threshold limit, the smart house air conditioner will be switched on instead to keep the temperature inside the house cooler.
Research Survey
Smart Home Systems
Apple HomeKit
Apple HomeKit is a system that allows access all your smart home devices in centralized space in Apple OS instead of one application per devices which causes inconvenience and time-consumed just to variation settings. Adjustments such as lights, thermostats and locks can be made with a tap on mobile phones via Apple Home application. Apple HomeKit’s connecting capability is limited to certain brand. (Chang 2017)
How does it work?
Connect device to either Bluetooth or WIFI
Open the Home app, add compatible device
Tap to turn on or off the device
Can create custom scenes: settings of multiple device for certain mood
May command Siri to control the devices
Amazon Echo & Alexa
Amazon Echo & Alexa makes the best pair of voice assistant system under your control. It can go from playing your favourite music, search web for news, shopping and smart home controls for compatible devices with voice commands. (Stables 2018)
How does it work?
Download mobile app – Alexa, available on iOS & Android
Navigate to menu -> Settings -> Set up new device (Choose Amazon Echo type)
Pair Alexa & Echo
Add smart home devices
Command Echo to do desired task
Create groups and scenes
Tap to turn on or off the device
May use voice command for smart home system control (Alexa, lights on)
Smart Home Device
Philips Hue
Philips Hue lighting is a smart LED lighting that connects to smart home system that offers an enormous range of colour settings to the extent of mixing colour plates for custom colour) and effects for various mood, settings and occasion in the house remotely. (Prospero 2018) Phillips Hue bulbs comes in different sizes and shapes and still looking very similarly to normal light bulbs.
How does it work?
Connect Philips Light and Philips Bridge
Powered up Philips Light and Hue Bridge to make sure they are discoverable
Download Hue application (available on iOS and Android)
Assign lightbulbs to room (for easier control)
Set the lights to desired lights, brightness or colour through the control from the apps
Tado Smart Thermostat
Tado Smart Thermostat is a smart thermostat that connects a home’s heating and air conditioning with home automation system. The Tado Smart Thermostat is connected to a bridge which wireless communicates with the thermostat wired into the back of router. The attractive LED display of ambient temperature and connection status with a press on button located on the thermostat. (Ludlow 2017)
How does it work?
Set up Thermostat connecting to bridge
May use app for manual controlling
Set desired temperature, fixed setting for day and night available
Block Diagram
Block diagram explain the structure of the system. First, the sensors will work as input components which collects the data input and passover to micro-controller to process the home automation system to function properly. Execution of the system will take place and the system will be checking in accordance to the limit threshold. The data will be forwarded to GSM modem and web server vise versa for accessing and controlling remotely.
Components and Descriptions
Global System for Mobile communication (GSM Modem)
SIM900 is a GSM compatible quad-band SMT Module which communicates in frequency range of 850/900/1800/1900MHz, establishes communication between Internet, SMS or oral communication. Through connecting this module with Raspberry Pi, user will be able to access the web server and communicates with the devices using internet.
Light Dependent Resistor (LDR)
Light Dependant Resistor is a light sensing circuit, which basically means it will react depending on the light intensity that falls on it. This component in our final circuit in a way that if there’s enough light in the room, the curtain will not be closed.
Light-Emitting Diode (LED)
Light-Emitting Diodes is a semiconductor device where when an electric current pass through it, it will emit visible light, signifying electric current occurrence successful.
Temperature Sensor
The LM35 temperature sensor is a high precision temperature sensor which calibrates directly in °Celsius. Although it may require more power voltage to power compared to TMP36, LM35 has proven to provide the best accuracy indoor within the widest temperature range (-55 °c …. + 150 °c).
Smoke Sensor
The smoke sensor MQ-2 is used to detect the presence of gas, smoke, hydrogen and so on. It requires only 5V to power it, and measurement can be taken as soon as possible due to its short reaction time. Its sensitivity can be adjusted by using potentiometer.
Logic Gates
AND Gate
Input 1 Input 2 Output
0 0 0
0 1 0
1 0 0
1 1 1
Table 1: Truth Table for AND Gate
OR Gate
Input 1 Input 2 Output
0 0 0
0 1 1
1 0 1
1 1 1
Table 2: Truth Table for OR Gate
XOR Gate
Input 1 Input 2 Output
0 0 0
0 1 1
1 0 1
1 1 0
Table 3: Truth Table for XOR Gate
NOT Gate
Input Output
1 0
0 1
Table 4: Truth Table for OR Gate
Simple Electronic Design Circuit
Figure 8 shows an example of a temperature monitoring circuit where LM35 (temperature sensor) is applied. In this design, LM35 is directly connected to ESP8266, a Wi-Fi microchip with microcontroller capability. This is a temperature recorder that monitor the temperature, then stored the data and displayed it through web server allowing user to view the current temperature easily. The temperature of the room can be monitored anywhere, anytime through the web server.
From the above Figure 9, the ambient-light-controlled electromagnetic relay driver built around a standard photoresistor (LDR1) and two small general-purpose switching transistors T1 and T2. Where there is insufficient light falls on LDR1, the resistance become higher, causing voltage on base of T1 is low, driving the cut-off mode of transistor. When sufficient light falls on LDR1, base T1 will turn the high voltage into conduction. Potentiometer VR1 can be used to adjust the switching sensitivity.
Circuit Design Description
Our smart home system has 3 main automation applications. Curtain & lighting receive their input from a Light Dependency Diode (LDR) and adjust the mode accordingly. If there is enough nature light at the sensor sense in the living room which exceed a certain threshold of lux, it will activate the curtain and switch off the lighting in the room. If there is not enough natural light in the room, curtain will be closed, and lighting will be switch on.
The second automation application is the fire sprinkler. 2 types of temperature sensor are embedded inside the house. The first temperature type sensors have a threshold of 30℃ and the second type of temperature sensors have a threshold of 50℃. When temperature exceeds 30℃ and 50℃ respectively, they will emit a high signal to the microcontroller. Besides that, smoke sensors are also installed at strategic locations. The fan and the AC are switched on automatically when they sense the ambient temperature exceeds 30℃. The fan and the AC must stop working when ambient temperature exceeds 50℃ to prevent fire from spreading. The fire sprinkler must be activated when the system senses that the temperature exceeds 50℃ and there is smoke present.
CEDAR Logic for Fire Sprinkler System and Fan & AC
Possible situation:
Temp < 30, no smoke
30 < Temp < 50, no smoke
Temp > 50, smoke present
Truth table for Fire Sprinkler System and Fan & AC
Temperature Sensor 30℃ Temperature Sensor 50℃ Smoke Sensor Output
Sprinkler Fan & AC
0 0 0 0 0
0 0 1 0 0
0 1 0 0 0
0 1 1 0 0
1 0 0 0 1
1 0 1 0 1
1 1 0 0 0
1 1 1 1 0
*shaded rows are for impossible scenario
CEDAR Logic for Curtain & Lighting
Possible situation:
Light > 1500 lux
Light <= 1500 lux
Light > 1500 lux and AC is on
Light<=1500 lux and AC is on
Truth table for Curtain & Lighting
LDR AC Curtain* Lighting**
1 1 0 0
1 0 1 0
0 1 1 1
0 0 0 1
*State for curtain **state for lighting
0- curtain is closed 0- lighting is off
1- curtain is open 1- lighting is on
Final Flowchart
Final Truth Table
Temperature Sensor 30℃ Temperature Sensor 50℃ Smoke Sensor LDR Output
Sprinkler Fan & AC Curtain Lighting
0 0 0 0 0 0 0 1
0 0 1 0 0 0 0 1
0 1 0 – 0 0 – –
0 1 1 – 0 0 – –
1 0 0 0 0 1 1 1
1 0 1 1 0 1 0 0
1 1 0 – 0 0 – –
1 1 1 1 1 0 1 0
Table 5: Final Truth Table for final circuit
Final Circuit
Figure 13: Final Circuit
Unresolved Problems
Assumptions
Conclusion
References