PDACSPDACS

Final Presentation

Michelle Berger

John Curtin

Trey Griffin

Aaron King

Michael Nordfelt

Jeffrey Whitted

PDACSPDACS

Portable

Digital

Audio

Codec

System

PDACS is...

PDACSPDACS

Overview

PDACS is a portable device designed for capturing, compressing, storing, playback, and retrieval of digital audio data. It samples speech, performs compression, and stores it in non-volatile memory. The data can then later be played back directly from the device or transferred to a PC by means of the serial port interface.

PDACSPDACS

PDACSPDACS

Divide-and-Conquer Methodology

• Audio Subsystem

• Memory Subsystem

• Compression Subsystem

• Serial Port Subsystem

• GUI Application

PDACSPDACS

Mic JackMic

Amp

Analog/DigitalConverter

Digital/AnalogConverter

FilterClock

Spkr

Input Filter(buffered output,

3 kHz LP)

Output Filter(3kHz LP)

InverterOutput Amp

8-bit bus

Bus Interface to Xilinx (8kHz sampling)

Chip

Select

8-bit bus

DC Offset

AUDIO IN

AUDIO OUT

8-bit, 8kHz, Mono

PDACSPDACS

Problems in Building Audio Subsystem

• D/A would not work• A/D quit working (NO pin)• Input and output signals not amplified• Input and output signals not filtered• Microphone output needed DC offset

• Number one problem: General lack of knowledge about analog signal

PDACSPDACS

Memory Subsystem

• Atmel 16-Megabit 5-volt Serial DataFlash Memory

SignalAbbreviation

Signal Name Signal Description

SO Serial Output Data Output pin from the memory chipSCK Serial Clock Control signal from Xilinx to the memory chip

SI Serial Input Input pin to the memory chip(used for commands and data)

CS* Chip Select An active low signal that enables the memory to beread from or written to

RESET* Chip Reset An active low signal that will terminate theoperation in progress and reset the internal statemachine to an idle state

WP* Hardware PageWrite Protect Pin

An active low signal that forbids the first 256 pagesof main memory to be reprogrammed when asserted

PDACSPDACS

Memory Subsystem• Atmel 16-Megabit 5-volt Serial DataFlash

Memory

PDACSPDACS

• Read command(opcode = 52H)

• Buffer write command(opcode = 84H[buffer1], 87H [buffer2])

• Main memory program command(opcode = 83H[buffer1], 86H[buffer2])

Memory Subsystem

Opcode Page address Byte address Don’t Care [X](10 bits) (12 bits) (10 bits) (32 bits)

Opcode Don’t Care [X] Buffer address (10 bits) (12 bits) (10 bits)

Opcode Page address Don’t Care [X](10 bits) (12 bits) (10 bits)

PDACSPDACS

Memory SubsystemVerilog module flow:• Determine read, buffer write, or main memory

program and set matching opcode• Clock in the necessary bits one at a time• Update control variables and test the edge

conditions

PDACSPDACS

Compression Algorithms

Algorithms Studied• Run Length Encoding RLE• DCT• Companding• Vector Encoding

PDACSPDACS

Compression Algorithms

DCT

• Performs Discrete Cosine Transforms on a series of data.

• Divides the result by a quantitization matrix

• The results usually contain long runs of zeroes, ideal for run length encoding

PDACSPDACS

Compression Algorithms

IDCT

16,17,18,19,20,21,22,23 55, -6, 0, 0, 0, 0, 0, 0 QuantitizationMatrix

55, -6, 0, 0, 0, 0, 0, 0

DCT

QuantitizationMatrix

16,16,17,18,20,21,21,22

PDACSPDACS

Compression Algorithms

Companding/Vector Encoding

• Companding is a lossy compression– Reduces the number of bits for each sample

• Vector encoding– encodes the differences between the

companded values

PDACSPDACS

Serial Subsystem

Specs:• Consists of two chips (16550 UART and Max232)

and a 9-pin serial jack• Pin count to the Xilinx stands at 17• Have robust serial module that is capable of

reading and writing to memory based on control characters from PC

PDACSPDACS

Serial SubsystemDownload

Memory XILINX 16550 ApplicationMaster Reset

DSR

DSR Active

Notify GetData

Data

Last Block

DataData

DataData

Set DTR

DTR

DTR (Data finished) DSR

Max232(Computer Ready)

‘aa’‘aa’

PDACSPDACS

Serial SubsystemUpload

Memory XILINX 16550 ApplicationMaster Reset

DSR

DSR Active

Write Data

Data

Data

DTR

Max232(Computer Ready)

‘bb’‘bb’

Data

DataWrite Data

ResetDTR

(End of File)DSR

PDACSPDACS

GUI

• Allows user to access the serial port and download the data from the device.

• Also allows user to upload file to device.• The GUI was developed in Visual Basic (to allow

rapid development)• Visual Basic allows read/writing to all control

lines for serial communication.

PDACSPDACS

GUI

• Decompresses sound files through software, output to a .wav file

• Allows user to play

a audio file

through the Windows

multimedia player.

PDACSPDACS

System Integration

•Memory to Serial Integration•Audio to Memory•Audio to Codec•Codec to Memory•Serial to GUI

PDACSPDACS

PDACSPDACS

What We Wanted to Have

• Real-time compression of 8-bit 8KHz speech• Storage & retrieval of sound files• Real-time decompression of stored audio • Serial interface with PC for storage and archiving• GUI application that facilitates easy retrieval• Built in controls for recording, playback &

deletion

PDACSPDACS

What We Have• Real Time Capture and Storage of 8-bit 8 kHz

speech• Storage & retrieval of sound files• Serial Interface with the PC for storage and

archiving• GUI application that facilitates easy retrieval• Controls for recording playback and deletion• Pass through playback of 8-bit 8KHz audio

PDACSPDACS

What We Dropped

• Portability• Power Subsystem• Completely Integrated Finished Product• Real-time compression & decompression of audio

PDACSPDACS

And Remember…

Xilinx is cool, but it’s occasionally bogus.

-Scott