"Product design and development is a combination of creativity and analysis. But it depends on communication." - Michael Bremer

THINK about these HOME LEARN about me TASTE these links SEE my pictures SIGN / VIEW my guestbook     Last Update : Aug 14, 2003  My Research Work  Electrical Engg.  MSP430  Free Space Optics  Communication Systems  Ad-Hoc Networks  Ericsson BT Modules  Linear Prediction  Multi-user Detection    Wireless Channel Model

GENERAL PURPOSE BLUETOOTH INTERFACE
The first stage of the project has been successfully completed. Here is the Stage I report and the presentation.

The aim of this project is to make a generic bluetooth card which could be used to transmit data from one device to another. The device is required to be Bluetooth Specifications V1.1 compliant. The module should be capable of taking in Digital as well as Analog input, packetise the data and send it across the available Bluetooth connection. The block diagram of the system is as follows

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PROPOSED SYSTEM FUNCTION & JUSTIFICATION
The system is envisaged to be a generic interface between the Bluetooth network and any device. This system is planned to be a part of a bigger project which aims at providing a complete Bluetooth solution for applications like home networking.

It should provide a seamless connection between any device communicating through a RS232 port and an available Bluetooth network on the other side. This will enable devices to communicate with each other using their own protocols over a common network. The flexibility and advantages of the Bluetooth architecture are the major features of the system.

PRINCIPLE OF OPERATION OF THE SYSTEM
Bluetooth is a technology for short-range (~10-100 m) wireless communication. It works by providing automatic, seamless connectivity between devices by forming ad-hoc networks. It operates at the international license free band (ISM Band) of 2.4 GHz. This standard (defined by Bluetooth SIG www.bluetooth.org) enables devices to, without user invervention, connect to each other and form networks (called piconets) to provide services to users. The Bluetooth protocol consists of 5 basic layers :

• Radio layer : This layer handles the RF communication.
• Baseband layer : This controls the radio layer, provides Frequency Hop Sequences and low level encryption.
• Link Manager Protocol (LMP) : Provides the functions of piconet management, link configuration and security.
• Host Controller Interface : This is needed for communication between LMP and the higher layers if they (higher layers) are present on a different chip.
• L2CAP : This provides the network layer functions to applications and higher protocols. e.g. Segmentation and Reassembly of packets, etc.

DETAILED DESIGN

Our aim here is to put together a Bluetooth module which can be interfaced with any device to provide Bluetooth connectivity. We will be following Bluetooth 1.1 specifications available at www.bluetooth.com.Since this is primarily meant for large scale usage, the device should be compact and cost effective.We have partitioned the system as follows :

The main idea behind the design is a microcontroller to run the L2CAP layer and using a commercial Bluetooth Module for the lower layers. A detailed description of the blocks are as follows:-

• Serial Interface (RS232 port) : This part consists of a standard RS232 port and the driver required. This enables the microcontroller to communicate with the device.
• Analog Interface : This is an optional part which would enable direct analog signals to be given to the microcontroller.
• Microcontroller : This is the central part of the implementation. It provides the functionality of the L2CAP layer of the Bluetooth stack and enables Multiplexing of protocols, segmentation and reassembly of packets from input to output.