Christoph Nolte and Manuel Schreiner, Applications Engineers, Embedded Solutions at Fujitsu Semiconductor Europe take a closer look at the home of the future, integrating super fast microcontrollers for an advanced, fully automated living experience that maximises on energy efficiency.
Ethernet technology is widely used, technically mature, reliable, cost-effective and suitable for universal use. These properties make a strong case for the use of Ethernet solutions in the area of home automation. A new development in this field are microcontrollers with twin Ethernet ports.
These products enable a safer and more efficient design of network architectures in buildings. Alongside improvements in terms of functional reliability, new applications are being opened up in home automation and the control systems can be designed to be more user-friendly.
Ring topologies and daisy chaining have long been established as standard technologies for industrial applications. Ethernet/IP, POWERLINK and PROFINET are examples of industrial protocols, which are based on Ethernet and use this type of ring topology.
Here
, the term ‘daisy chaining’ initially only describes the approach of series-connecting multiple devices to create a chain (Figure 1). Compared with a star topology, this layout not only saves cabling costs (with Power over Ethernet (PoE) even on the power supply), but also allows for longer communication lines.
With Ethernet networking, every node actively forwards the incoming data to the next node. As a result, not only is the cable extended, but each node also acts as a repeater, allowing nodes to be separated by distances of up to 100m.
However, daisy chaining alone also has its disadvantages: If one of the nodes fails, the nodes further down the line can no longer be addressed. To overcome this issue and introduce redundancy into the system, daisy chains are often set-up in a ring structure.
Alongside the redundancy in the network, it is also helpful if a node can monitor itself in order to detect and report any failures and, if applicable, restore itself to normal status. To keep latency between modes to a minimum, Fujitsu Semiconductor Europe has developed the FM3 microcontroller series, with twin Ethernet relying primarily on high-levels of processing power. Due to a 144MHz core, the high-performance family is one of the fastest of its type with embedded flash memory currently on the market.
Ethernet in a ‘smart home’
In particular, the use of one microcontroller with two Ethernet ports opens up potential for gateway applications such as LIN, CAN, UART, I2C, USB Host/Device and SPI interfaces to Ethernet (Figure 2).
With the aid of these applications, wireless technology can be integrated with relative ease, facilitating the installation of radio-controlled devices such as actuators and sensors in the network. Typical actuators in home automation include relays for switching lights or equipment, motors for operating windows and shutters, door openers and similar.
Sensors, for example, are used to detect temperature, moisture, carbon monoxide, gas, smoke, light, rain, water levels, occupancy or movement.
A heating module or heating gateway connected to the Ethernet could, for example, send wireless signals to control battery-powered thermostats located directly on the radiators.
Wireless integration of the data from indoor and outdoor temperature sensors can also be easily set-up. Since the heating is directly connected to the home network, windows and shutters can also be included in the system to ensure that the optimum temperature is maintained in the home.
An alarm system module can scan a range of sensors either wirelessly or via separate, secure wiring. These sensors can be used to detect not only intruders, but also other safety-related events such as smoke or gas/carbon monoxide leaks, and can then immediately notify the police or fire brigade.
In combination with a GSM module, it would even be possible to send out an emergency call via Ethernet using Voice over IP technology.
Ethernet can also be used for controlling power supply systems, for example to optimally align solar power systems or wind turbines and forward data relating to the generated power.
With the aid of special motor control I/O devices, some of the derivatives of the FM3 family, including the high performance family with Ethernet, are also able to ‘drive’ various types of generator, such as brushless generators, in addition to motors.
Consequently, a set-up with three independent motor control I/O devices will enable users to generate and store DC current from the power produced with the generator, convert this energy back into AC current if required and then use this, for example, to power a motor for adjusting the wind turbine so that it is facing in the direction of the wind.
In addition, it is also possible to perfectly adjust the alignment of solar power modules using two motors, whereby the electric power, which is generated can be converted back into AC current if required.
The Ethernet system in turn helps to inform the home bus system about the amount of energy, which is currently to be expected.
Electrical consumers, which can be activated regardless of the time of day, can then be switched on when the supply conditions are ideal. Examples for this type of device include washing machines and dishwashers.
With the imminent development of electric vehicles, this type of set-up could be employed to ensure that the vehicles are only re-charged when sufficient energy is available.
A high-performance microcontroller with twin Ethernet is also ideal for the necessary operating terminals, because a display can be actuated via an external graphics controller (Figure 3).
State-of-the-art capacitive technology can be used to deliver an easy-to-use touch-screen display. Fujitsu offers a touch software library for this purpose, which is capable of controlling up to 32 analogue/digital channels with a resolution of 12 bits per microcontroller. In addition to direct physical operation via the operating terminal, it is also possible to change settings online. Alongside proprietary applications for different systems, the web browser itself is a popular and universal tool for virtually re-constructing the operating terminal.
For live testing, the entire system can be operated via the web browser of the connected client with the aid of a web server. Many devices now also offer an integrated web server. This already allows easy operation, configuration and remote maintenance of printers, routers and Network Attached Systems (NAS) via a web browser.
While the browser takes on the role of graphical user interface (GUI), the embedded system delivers the necessary data. Particularly in the case of embedded systems, this means that no further development costs are necessary.
In addition, the new HTML 5 standard also supports so-called WebSockets. These allow even faster feedback to the GUI and could completely supersede Java applets in the future. Furthermore, users can also be sure that a web-based GUI will run on all operating systems, such as Windows, Linux or Mac OS X, as well as on smartphones and tablets, for example with iOS, webOS or Android, meaning that the otherwise complex and time-consuming process of porting to a wide range of different systems is no longer necessary.
On top of this, no drivers are needed in order to communicate with the embedded system. It is ready for use as soon as it is connected to the network – without installation of any software or drivers and without the need for corresponding administration rights.
Levels of automation in the home are set to increase steadily in the future, as our desire to create a ‘feelgood zone’ at home increases in response to day-to-day stresses and ever-scarcer free time.
Home automation systems (Figure 4) are designed above all to make us feel comfortable, but without taking all of the work away from us in the process. The aim is not to allow us to spend all of our time lazing on the couch, but to ensure that the basic parameters and surrounding conditions are right. This includes, for example, comfortable conditions in terms of temperature, brightness, air and humidity. If we forget to switch a piece of equipment off or on, you can also control your home remotely.
The intelligent home is networked via Ethernet, which also integrates Internet (via an encrypted SSL connection), multimedia, PCs, smartphones etc. To reduce cabling outlay and costs, the bulk of the Ethernet is networked via a ring topology, and parts of the network are powered via PoE.
Various modules in the system can then share data not only with a control centre, but also with each other. The standard mains power supply of your home can also be supplemented with solar and/or wind power systems connected to your home bus system. The systems in your home are controlled via operating terminals with touch-screens, which are located on every floor.
A web server integrated in the system and native smartphone applications can be used to control your home remotely. A quick tour is the best way to see what it would be like to live in a house like this.
The home of the future scenario
Each morning starts with a simulated sunrise in the bedroom, two hours before the sun actually rises. The occupant is woken up with the sounds of his or her favourite music, while the bathroom is pre-heated and fresh coffee is brewed in the kitchen. During breakfast, the system notices that there is nobody in the shower rooms or bedroom, so it automatically vents these rooms and switches the heating back off again.
Once the last occupant has left the house, the alarm is activated. Any devices that have not been switched off are then automatically shut-down. Open doors and windows are closed and locked. While the family is out, the washing machine and dishwasher switch on automatically.
Due to the home’s internal weather monitoring station, which updates from the Internet, the system knows when the wind and solar power systems can deliver the optimum output.
When you are leaving the office after your day at work, you can also use your smartphone to notify the home system that you are on your way home earlier than usual. As nobody was home before, the heating and any devices on standby will have been shut-down or switched-off. The home then needs to be ‘woken up’ from its energy saving mode.
According to the schedule in the installed program, the home is then briefly aired before the heating is set to a comfortable temperature of 22°C. If the washing machine and dishwasher have not yet been switched-on due to lack of sunshine or wind during the day, then this takes place now. Once it starts to get dark, the shutters are automatically closed and the bedrooms are aired for five minutes.
Twin Ethernet microcontrollers (Figure 5) offer tailor-made technology for home automation and thus fit seamlessly into the company’s wider concept of ‘right-sized’ solutions.
At 1.25Mips/MHz, the ARM Cortex-M3 CPU architecture provides a good level of innate computer power. For any performance analysis, however, the microcontroller needs to be seen in the context of the overall system, which – alongside the processing core – comprises memory units, data buses and I/O blocks.
The FM3 family is one of the fastest ARM Cortex-M3 Flash microcontrollers currently on the market. This is firstly due to the high cycle rate of the CPU of up to 144MHz at which the derivatives can be operated, but secondly the company has also implemented a particularly reliable Flash memory, which is also considered one of the fastest available today.
This can be run at up to 72MHz without any wait state; thanks to the integral Flash Accelerator, it can also operate at speeds above 72MHz, yet still enables up to 100,000 erase/write cycles with more than 20 years of flash data integrity.
Another feature is the wide supply voltage range from 2.7 to 5.5V. In an industrial environment, the increased operating voltage boosts signal-to-noise ratio and improves reliable operation.
