ABISS: A Bluetooth Intelligent Sound System

Andrew BurksAndy Heck

Stephen LeotisBen Wallingford

PDR Presentation October 29, 2009 1

Project Overview

• Stream audio wirelessly via Bluetooth to the nearest receiver

• Provides wireless audio solution that moves with you

• Early adopters: tech-savvy gadget lovers• Sold in sets of two for $128

2Stephen Leotis

Design Objectives

• Monitor continuously all nearby Bluetooth receivers’ signal strength

• Switch audio stream to the Bluetooth receiver with highest signal strength

• Maintain compatibility with all Bluetooth devices

Stephen Leotis 3

System Diagram

4Stephen Leotis

Continuously monitor allBluetooth receivers in range

Stream audio to nearest receiver

Design Approach

• Bluetooth Receiver – Accepts signal via Bluetooth connection– Converts audio stream to analog signal– Outputs analog signal via TRS jack

• Proximity Awareness Software– Detects multiple receivers– Pairs with closest receiver

5Ben Wallingford

Hardware Design

• Receive Bluetooth signal from audio source• Transmit analog audio to speakers

Ben Wallingford 6

WT32 Bluetooth Module

WT32 Bluetooth Module

LM4808 Headphone

Amplifier Circuit

LM4808 Headphone

Amplifier Circuit

Audio Out3.5mm TRS

12V DC

BluetoothSignal

Breadboard Prototype

7Ben Wallingford

WT-32 Bluetooth Module LM4808 Audio Amplifier

Power Regulator 1/8” TRS Jack

Software Design

• Find and monitor all Bluetooth receivers in range

• Stream audio automatically to nearest Bluetooth receiver

• Run as background process• Implemented initially on Mac OS X

Andrew Burks 8

Project Demonstration

• Demonstrate in the Klaus Building• Use two receivers and two speaker systems• Begin playing music and move between rooms• Confirm proper functionality of audio

streaming to the nearest ABISS receiver

9Andrew Burks

Project Demonstration

10Andrew Burks

Problems and Resolutions

• Programming Bluetooth module– Built RS232 serial programmer circuit– Initialized Bluetooth module settings to A2DP

audio sink

• Rectifying audio quality– Built LM4808 headphone amplifier circuit– Removed noise and increased audio quality and

volume

11Andy Heck

Current Status

• Hardware– Working prototype of Bluetooth receiver on

breadboard.– Designing PCB for Bluetooth receiver.

• Software– Detects and displays the signal strength of all

nearby Bluetooth capable devices.– Implementing audio switching functionality.

Andy Heck 12

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