Home automation software design

The range of sensors that should be considered include:. The information provided by these sensors after signal conditioning is used by the processor to make several important decisions regarding the appliances and when to switch them ON or OFF. It should be able to prevent most types of intrusion. Even if the system is broken into, it should be able to send signals to the user and the nearest police station. It also necessary to hide as many components as possible from direct access via the main control panel, preventing it from being turned into a black box.

It should also be able to send and comprehend encoded data while communicating with other devices. This will prevent intruders from tapping into the system and using the same interface to hack devices. Topology: Topology defines the way home automation control units interact with each other. A star type topology is the most commonly used as it makes use of a central control unit CCU interacting with all the available remote control units RCUs and taking over decision making responsibilities.

After it has assessed the input from the sensors and made any necessary decisions, the CCU sends the command back to the RCU to take a specific action.

Another topology to be considered is a mesh topology, which has no CCU and makes use of a constellation of control units of roughly equal intelligence and capability connected with each other. Each unit sends information on the network which is shared by all the units. Each Unit is independent and makes its own decisions based on the shared information.

The choice of system topology governs the selection of communication interfaces such as ZigBee, RF, Bluetooth, etc. Depth of automation: System design is affected by the requirements ranging from simple control of lights in the house to controlling all appliances and the security system. Each requirement affects the overall design, and developers need to determine the most optimized way to perform all the tasks with the lowest cost and complexity. Despite the internal system complexity, the system should be easy to use and not pose barriers to its operation by a household user.

Cost: This is the most important aspect of system design as system complexity and depth of automation determine the cost. A highly complex — and thus costly — system can deter customers from purchasing and installing it in their house. The cost of the system is directly linked with the number of components, interface used, and complexity of design of firmware and hardware. While there should be no compromise on the quality of hardware and software, the number of components in the system can be decreased to reduce the overall cost and system size as well.

Rather than the traditional component-based approach, lower cost can be achieved using System-on-Chips SoC that integrate multiple peripherals and a processor into the same IC. The architecture of a home automation system While there are several topologies to choose from, for the sake of simplicity we focus in this article on a star topology-based home automation system and its two types of control units, the CCU and multiple RCUs Figure 3. Common features of a central control unit are:.

It has a set of sensors to sense the surrounding environment. Based on the current conditions, it can decide upon a course of action. Common features of a room control unit are:. Central Control Unit This is the main unit responsible for monitoring the complete home automation system. It interfaces with other system blocks to perform required tasks.

The most common interfaces on a CCU are shown in Figure 4. Some of these interfaces are optional and are used as per the system and user requirements. Sensors: Sensors are the eyes of a home automation system.

Basic home automation sensors include temperature sensors, humidity sensors, light sensors, and gas sensors. Data in the form of signals from these sensors can be used to control the various appliances directly without any human intervention. For example, lights can be automatically switched on upon sunset, an air conditioner can be switched off automatically when no movement is detected in the house for a half hour, or an alarm can be raised when the system detects a LPG leakage event.

Analog Front End AFE : Each sensor converts the change in a physical parameter such as temperature or light intensity to a similar change in electrical parameters such as resistance or capacitance.

These physical quantities must be converted to a voltage equivalent so that the microcontroller can identify the variation in environment. For this purpose, an analog front end AFE is interfaced with analog sensors. The AFE preconditions output signals coming from the sensors by filtering out noise and providing required gain to the signals. AFEs are also required to calibrate the system for sensor readings, thus providing a base value for the system to identify any changes in the environment.

Remote Connectivity: Depending on need and various design considerations, users may need to be able to control the system and appliances remotely. The two most common ways of doing this are using GSM-based mobile telephony and the Internet.

GSM, Ethernet, or both interfaces can be used to communicate with the system from a remote location. These connectivity options generally require a serial communication protocol like SPI or I2C to communicate with the host processor.

Manual Control: In a typical home automation system, there are situations when the user needs to manually control one or more appliances. Manual user control should be authorized by the system to prevent control of the system by an intruder and the shutting down of intrusion alerts. An accurate time source is required to control appliances using time-based settings. An external RTC can be used to maintain time for the system and the central controller can access it to receive current time related information.

This technology is quickly gaining traction in embedded applications for communications and information sharing. Power Monitor: In any house there are many electrical appliances that are sensitive to voltage fluctuations and need a reliable supply voltage within a specific range to work as expected.

A power monitor block can be added to the Central Control Unit to check the instantaneous power supply voltage. This block brings down the voltage level of power supply to a level where the system can monitor it using an ADC. Using input from this block, the controller can detect low voltage, high voltage, and voltage fluctuation situations. In extreme cases, this block can instruct RCUs to switch off sensitive appliances to prevent damage. An example of a simple power monitor circuit is given in Figure 5 and can be easily implemented into automation systems.

In the power monitor circuit, the potential divider circuit brings down the mains voltage to a lower voltage which can be safely measured by a microcontroller ADC. The peak detector circuit creates an envelope on the scaled down voltage that gets measured. The protection diode protects the microcontroller by limiting the maximum voltage to its Zener Voltage Vz.

This unit receives control commands from the central control unitand also from user buttons that can directly control appliances. Theroom control unit can also have various types of sensors built in tolocally monitor the appliances in the respective room.

Optionally, if Bluetooth is used for local communication, thenthe user can control the system using a smart phone. An RCU is anauxiliary unit responsible for monitoring local environmentalconditions and controlling local appliances connected to the unit.

RCUsare essential for a large house with multiple rooms. These unitscommunicate the local environmental conditions to the central controlunit, and also control the local appliances based on commands from theCCU.

This unit interfaces with other blocks in the system to perform therequired tasks. A block level diagram and description of a RCU is givenin Figure 6. Buttons: These buttons are provided to directly control the appliances, enablingthe user to directly switch on or off any appliance using aswitchboard.

Plus, not only does it make life a little easier, it can also help you save time and money. CAD Pro is great for beginners and professionals when creating home automation drawings. Cad Pro helps you create any automated house plan, add elements outlets, light fixtures, alarms, doors, windows, and even furniture. Quickly align and arrange everything perfectly with the Smart Alignment Tools. Plus, our automated home design software includes beautiful colors and textures for floors, counters, and walls.

Home automation drawings are easy for anyone with CAD Pro — from beginner to expert. Placing a PIR sensor is the same story, make sure the range is fine and that it covers whatever you expect it to. The answer is pretty simple and follows the topic : Save yourself some time and plan things.

This will make the whole project a lot more consistent. Home automation is not as simple as buying a wireless power socket at the local store. This is so much more.

Please check my other instructables, I'm planning to write more practical ones. I quite liked taking time to write this one. Could you explain why you chose pidome? What's the difference with Openhab? Is it more simple, or more secure? Reply 4 years ago. For the time being, it is more a personal preference. I'll probably work on a deeper instructable for this matter. Final note, I'm also trying to use a RPi as much as possible since it is already available and underused for the Garage Opener.

More by the author:. This covers basic things like : What is home automation? First check if that actually matches your expectations. Where to start? Pretty easy, start where you are, probably at home. Do you know it inside out? What can I do? About anything but you need to plan and know your limits.

This includes staying alive works any day, including evenings. What are the pieces of this puzzle? More complex, there are many shapes and it's very easy to lose some pieces.

We'll try to just keep our sanity. How to put that together? Smart home : Making the house "aware" of itself or giving it ability to do things. Building automation : Indeed, as a lazy geek, I want a computer to make what I don't want to do myself. Switches and sensors : Look at this like eyes and fingers of the home, without both that won't do much.

Central hub : So that clever home needs a brain? One brain to rule all things. That'll be the controller. Interacted : The home can have its own life but we want to be part of it. That's our place. Wait, how to chat with a house? Internet cloud services : I don't like that, some machine somewhere shouldn't know about me having the washer on. But that's personal. Don't forget "there's no such thing as the cloud, its someone else's computer".

Wait, a service is much more that a computer. Traveling by plane is more than having his own plane. Checklist : Do you already have some ideas? List what you want to model : Building, floors, rooms, systems, appliances List what you DON'T feel comfortable with : Maybe you want to skip security equipments or access control.

Put priorities : For true DIY, you'll be alone most of the time. Focus on achievements. Evaluate cost : Eliminate what you think is over-expensive or not worth it. Evaluate skills : I'm currently unable to design anything in 3D, still that's a skill I'd like to acquire.

For this instructable I'll assume things about my own experience : Home has roughly 15 rooms. That's quite a lot to "just start something". I'm using cheap D1 Mini clones from Ali Express.

A few months ago I even didn't had a soldering iron. I want to actually use that, I'll try to reach to "3D printed enclosures installed around the home".

Not yet achieved There is some dimension of "wife acceptance". This has to be useful AND usable. Tools Automating your home requires some planning. What to do? The lesson learn It falls to basics. Start by simple things like lights. Maybe next time : Before putting too much effort on designing absolutely everything, what are your priorities? Many things When I've written "know your place inside out", I also meant when not at home. Now that we have the overview of whatever we'd like to control, what can we actually control?

Obviously, as long as it is electrical, there is some kind of interface; whatever what it is. Water valve : Tank filling, plants watering, garden waterfall, fuel heating, well Outdoor Day: Close curtains to prevent heat from direct sunlight Night: "I'm home but it's fake" Welcome: Alley lights for guests Security : All lights ON Garden watering Pool heating Just like the rest, as long as you can control it somehow, there's room for automation.

Back to some pragmatism, what can we achieve? Any modification to your home must be studied, planned and executed by a knowledge person. Some theory Home automation assumes there is a controller allowed to know about everything.

Devices will be spread all around the place. Better know where you want them to be. Once we have a smart controller in the place, it must be able to communicate with the devices. Disclaimer Yes this is getting technical, sorry. Sorry there are so many ways out there to solve such topics :-O Taking that to the next level There are now many ways to communicate between "controller" and the different "nodes".

Connections between controller and devices : Wireless or wired? Power supply : From wall outlet, battery powered or solar charged maybe? It is described like this by its author : "An instance of a physical piece of hardware an Arduino, an ESP I'll use PiDome on a Raspberry Pi.

One or more devices to monitor and interact with your home. I'll use D1 Mini and Homie. A network to connect all that together.