We* designed and developed a system based on wireless control mechanism. The GUI controls the system outputs, turning on/off the light and also the other control unit is the fan.
Through the introduction of the Internet-of-Things technology, anybody may establish own wireless sensor networks and Internet-of-Things applications. It is very easy to combine with GUI interface and control the electricity switch.
In the following figure, the system structure and technical properties of an application on wireless controlled outputs for both light and machine control can be seen.
The structure is working at ISM band with 2.4 GHz central frequency ad 2Mbps bandwidth to air with maximal distance of 100 meters. First, the study began with 2Mbps bandwidth and approximately 25m indoor distance was operated successfully, however, due to the very small amount of data transfer, it has become apparent that we don’t need a bandwidth of 2Mbps, thus, in order to increase the distance, we reduced the bandwidth to 256 Kbps and the maximum communication distance then reached to 100 meters.
In the center of the system, we use the Raspberry PI with Linux operating system, which is used as HUB or "Central Management Unit" with the connection accessed via 3G / GPRS or other ADSL or fiber over the Web.
Sockets, sensors or RS232 - RS485 clients are equipped with the "Arduino Pro Mini" model microcontroller cards.
Clients communicate with HUB through Nordic NRF24L01+ transceiver.
Today, the "Zigbee" protocol is commonly used in some areas such as the mesh network, the Smart Home Network, etc. Because of the "Zigbee" increases our of R & D costs and also because of the additional cost of bringing ZigBee development license, Nordic companies’ lower cost of tranciever NRF24L01 + model is preferred in this work.
Also, due allowing development, the development of our own communication protocol continues at the same time.
Basic NRF24L01 procedure is used on the system we are currently working on, but to create an advanced protocol and provide a standard, our development process still continues to take the advantage of all the opportunities of mesh network.
The GUI interface is used to control the two system output over Raspberry Pi mainboard.
Sample views of power control can be seen in the following images.
We developed a controlling API which is named as “Bohemian API”. The Bohemian API is developed by Java EE7 standards and runs on Glassfish Server on Raspberry Pi. Running a GUI application in Raspberry Pi, which shows that it is very costly for memory and CPU usage. More lightweight web application is required for similar applications. We worked with the Glassfish in the very first time. It is really lightweight :) because we did not expect to run our application.
We determined to configure a new protocol which is automatically configured and used with other transceivers such as NRF24L01, automatically allowing to establish a self-forming network, secure, and allowing to extend NRF24L01’s 6 node star network structure to thousands node.
We see that the communication and interaction of connected devices could be simpler to manage them. The communication standards as architectural standard model and security models are necessarily parts of the Internet of Things.
Video: https://www.youtube.com/watch?v=aJ6TQlwmBB8
*Goksal Adiguzel
*Arzu Behiye Tarimci
*Asuman Savascihabes
