Bluetooth Enabled Wireless Mouse and Keyboard Interconnectivity

Bluetooth Enabled Wireless Mouse and Keyboard Interconnectivity Kenneth Carey R.A. Guinee and Fergus O’ ReillyDepartment of Electronic Engineering Cork Institute of Technology, Cork, IRELAND Abstract - The term Bluetooth refers to an open specification for a technology to enable shortrange wireless voice and data communications anywhere in the world. This specification is a result of the co-operation of many companies within an organization called the Bluetooth Special Interest Group. Due to its RF nature, devices need not be within line-of-sight and may even connect through walls or other non-metal objects. This allows for applications such as a cell phone in a pocket or a briefcase acting as a modem for a laptop or a PDA. This paper describes the development of a wireless mouse and keyboard application using Ericsson Bluetooth Development Kits (EBDK) and a protocol stack encapsulated in an Active- X component.1. INTRODUCTION Bluetooth is the name given to a global standard that: • eliminates wires and cables between both stationary and mobile devices • facilitates both data and voice communication • offers the possibility of ad hoc networks and delivers the ultimate synchronicity between all your personal devices Bluetooth uses short-range radio links, intended to replace the cables connecting portable and/or fixed electronic devices. It is envisaged that it will allow for the replacement of the many propriety cables that connect one device to another with one universal radio link. Its key features are robustness, low complexity, low power and low cost. Designed to operate in noisy frequency environments, the Bluetooth radio uses a fast acknowledgement and frequency hopping scheme to make the link robust. Bluetooth radio modules operate in the unlicensed ISM band at 2.4GHz, and avoid interference from other signals by hopping to a new frequency after transmitting or receiving a packet. Compared with other systems in the same frequency band, the Bluetooth radio hops faster and uses shorter packets. The Bluetooth wireless technology comprises hardware, software and interoperability requirements. The idea was conceived by engineers at Swedish telecommunication manufacturer Telefonaktiebolaget LM Ericsson who realized the potential of global short-range wireless communications. In 1994 Ericsson had begun a project to study the feasibility of a low power and low cost radio interface to eliminate cables between mobile phones and their accessories. Believing that the technology was more likely to be accepted, and thus more powerful, if it was adopted and refined by an industry group that could produce an open, common specification, Ericsson and several leading companies formed the Bluetooth Special Interest Group (SIG) to focus on the development of an open specification.The term Bluetooth comes from Harald Blatand, who was King of Denmark from approximately AD 940 to 985. One of his skills was to make people talk to each other, and during his rule Denmark and Norway were Christianised and united. “Blatand” roughly translates to Bluetooth and for a technology with its origins in Scandinavia, it seemed appropriate to name the technology which, many believe will unite electronic and telecommunications industries after King Harald. A key feature of the Bluetooth specification is that it aims to allow devices from lots of different manufacturers to work with one another. Bluetooth does not just define a radio system, but also defines a software stack to enable applications to find other Bluetooth devices in the area, discover what services they have to offer, and use those services[1]. Similarly to the OSI, the Specification makes use of a layered approach in its protocol architecture. Interoperability is achieved when the application in remote devices run over identical protocol stacks. The main advantage Bluetooth technology will have over other wireless technologies, such as infrared, is its ability to form Personal Area Networks or Piconets. Bluetooth units that come within range of each other can set up ad hoc point-to-point and/or pointto-multipoint connections or piconets. One of the participating units becomes a master of the piconet, while all other units become slaves. The project solution consisted of two different applications, a remote and local, running on a remote and local PC respectfully (Fig. 1). The applications were developed using two Ericsson Bluetooth Development Kits and a protocol stack encapsulated in an Active-X component called C-Stack[2]. Developed by Ogenek Toranta, C-Stack is an Active-X component, which encapsulates within itself the upper layers of the protocol stack. C-Stack is a simple, reliable, hardware independent stack and being an Active-X component it allows the user to develop applications in Visual Basic.Local ConfigurationRemote ConfigurationFig.1 Application Configuration2. DEVELOPING THE APPLICATION The project solution consists of two different applications, a remote application and a local application running, on a remote and local PC respectfully. The term “local” refers to the PC, Bluetooth device and application from which the mouse and keyboard data is sent, while the term “remote” refers to the PC, Bluetooth device and application which, intercepts the data transferred and simulates the mouse or simulates a key press. Each PC had an Ericsson Bluetooth Development Kit (EBDK) connected to it through the COM port. The remote application is similar to the local application in that both share the same user interface and similar connection establishment routines. Two applications were required because of the divided structure of the protocol stack. The local application was responsible for establishing the connection with the remote device and then transferring the data to the remote PC. The remote performs various actions such as setting the mouse co-ordinates or simulating a key press, depending on the data sent.2.1Establishing a ConnectionThe main steps involved in establishing a connection between the Bluetooth devices are outlined in Fig. 2. Both remote and local applications determine whether an EBDK is connected to the COM port. After opening the port the next step is to run the C -Stack on the host PCs. The Bluetooth addresses are then obtained from each device. The remote PC application then obtains the user name from the PC and finally turns on a timer which will run every millisecond to monitor for data arriving from the local PC. The remote application is now configured and a connection can now be established. The local device performs this establishment. It firstly pages for Bluetooth devices within a 10m radius. The Bluetooth addresses of any devices detected are stored and the user can now select, from the user interface, the device to communicate with.LOCALREMOTEFig. 2 Establishing a ConnectionFig. 3 Simulating Mouse and Keyboard Activity2.2Simulating Mouse and Keyboard ActivityThe steps involved in simulating mouse activity on the remote PC is outlined below (see Fig. 3). Similar methods are used to simulate keyboard operations. • • • • • • A channel is opened between the two Bluetooth devices by clicking the “Open Channel” command button on the Connect Mouse or Connect Keyboard UI screen. When the user on the local PC moves the mouse or presses a mouse button various events can be called, such as Form_MouseMove, Form_MouseClick and Form_DbClick[3]. The current mouse co-ordinates and button state are concatenated, converted into hex and stored in an array of type BYTE. The array is passed as a parameter to the C -Stack SendData method, along with the remote Bluetooth address, channel number and size of data to transmit. The method is then invoked. The remote application checks for incoming data and monitors for Bluetooth events using a Timer control, which calls a subroutine to carry out the above tasks. This subroutine stores the retrieved data, which is in hex form, in an array of type BYTE and the contents of this array are then converted to a string. The method also returns the number of the channel over which the data was transmitted. The subroutine uses the channel number to determine whether mouse or keyboard data was sent from the local PC and calls various routines depending on the action needed to be simulated. The mouse co-ordinates are then extracted and passed into the SetCursorPos APIs to position the cursor on the screen. The button state is passed to the mouse_event API which simulates a mouse down event. The User Interface•2.3Fig. 4 The User InterfaceDesigned using the SmartUI[4] Active X component, the UI provides an attractive and easy method of navigation. SmartUI is a User-Interface ActiveX, which allows you tocreate MenuBars, ToolBars, StatusBars, OutlookBars, TreeViews, ListBoxes, OptionLists, PropertyLists, TabStrips and many other lightweight UI objects with only one Active X. The User Interface of the local and remote applications is based upon the SmartUI TabStrip and SmartContainer. The TabStrip is similar in principal to the normal Windows TabStrip, giving an application a tabbed interface, but is more customisable and therefore more attractive. The TabStrip allows the user place images and text within each Tab Item. Used in conjunction with the SmartContainer, very user-friendly interfaces are possible. The SmartContainer is loaded with five picture boxes, each corresponding to a tab in the TabStrip and each containing various Visual Basic controls such as image boxes, text boxes and command buttons to provide interaction with the user. Clicking an item in the TabStrip will cause the corresponding picture box to appear. For example, clicking the “Connection Info.” Tab will cause the picture box containing the information on the Bluetooth devices and the status of the mouse and keyboard connections to load (Fig. 4). 3. RESULTS During the evaluation of the application a number of situations were encountered that may hinder future Bluetooth products. Firstly the range of EBDKs is 10m, but this is reduced due to the presence of obstacles. Demonstrations carried out in our project laboratory environment resulted in a less robust connection that could not be sustained over distances greater than 7 metres. Another major problem concerning Bluetooth is its transfer rate. Although this was not an issue in the implementation of the wireless mouse and keyboard, a maximum rate of 723Kbit/sec prevents Bluetooth from acting as a wireless networking solution. Table 1 below outlines the data rates possible using Bluetooth.Packet Type Max Symmetric Rate Max Asymmetric Forward Rate Max Asymmetric Reverse RateDM1 DH1 DM3 DH3 DM5 DH5 AUX1108.8 172.8 258.1 390.4 286.7 433.9 185.6108.8 172.8 387.2 585.6 477.8 723.2 185.6[5]108.8 172.8 54.4 86.4 36.3 57.6 185.6(D – Data, M – Medium rate, H – High rate. All rates in Kbits/sec)Table 1Since the project solution consists of connecting the EBDKs to the COM port of each PC, it was not feasible to measure data rate results to verify the results in Table 1 since the baud rate of the COM port limits any measurement, with the exception that a rate of 723Kbits/sec is easily sufficient for the mouse and keyboard application.Fig. 5. Bluetooth Combining with industry standards [6]4. CONCLUSION This project provided a great insight into the potential of Bluetooth as a wireless communication standard. The use of the C-Stack Active-X component and Visual Basic enabled the development of a wireless mouse and keyboard application. Similar techniques could be incorporated in the design of an embedded Bluetooth wireless mouse and keyboard solution. As for the future of Bluetooth, work is being carried out on a new specification that will address data rate and range issues. Bluetooth faces competition from technologies such IrDA and the new emerging Wi-Fi wireless LAN technology. One key factor that should lead to the eventual uptake of Bluetooth is its ability to allow consumers to bridge between the Internet and their personal portable devices. 3G will increase the value of Bluetooth mobile phones (Fig. 5) and PDAs are also expected to play a big role in early Bluetooth adoption, especially among professional users. Because of its low cost, low power consumption and excellent ad-hoc networking abilities, Bluetooth should become the leading short-range wireless technology within the next two years. ACKNOWLEDGEMENTS The author acknowledges the assistance of Srdjan Kroco of Ericcson Ireland, Richard Guinee and Fergus O’ Reilly for their help and assistance. REFERENCES [1] Brent Miller, Chatschik Bisdikian - Bluetooth Revealed, Prentice Hall PTR , Oct 2000 [2] [3] Rob Thayer - Visual Basic 6 Unleashed, SAMS, September 1998. [4] Developing Applications using the Smart UI – /SmartUI [5] The Bluetooth Specification - [6] ARC Group Bluetooth Industry Survey – 。