PDACS Final Presentation Michelle Berger John Curtin Trey Griffin Aaron King Michael Nordfelt Jeffrey Whitted

PDACS P ortable D igital A udio C odec S ystem PDACS is...

PDACS 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.

PDACS

PDACS Divide-and-Conquer Methodology Audio Subsystem Memory Subsystem Compression Subsystem Serial Port Subsystem GUI Application

PDACS Mic Jack Mic Amp Analog/Digital Converter Digital/Analog Converter Filter Clock Spkr Input Filter (buffered output, 3 kHz LP) Output Filter (3kHz LP) Inverter Output 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

PDACS 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

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

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

PDACS 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)

PDACS Memory Subsystem Verilog 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

PDACS Compression Algorithms Algorithms Studied Run Length Encoding RLE DCT Companding Vector Encoding

PDACS 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

PDACS Compression Algorithms IDCT 16,17,18,19,20,21,22,2355, -6, 0, 0, 0, 0, 0, 0 Quantitization Matrix 55, -6, 0, 0, 0, 0, 0, 0 DCT Quantitization Matrix 16,16,17,18,20,21,21,22

PDACS 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

PDACS 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

PDACS Serial Subsystem Download MemoryXILINX16550Application Master Reset DSR DSR Active Notify GetData Data Last Block Data Set DTR DTR DTR (Data finished)DSR Max232 (Computer Ready) ‘aa’

PDACS Serial Subsystem Upload MemoryXILINX16550Application Master Reset DSR DSR Active Write Data Data DTR Max232 (Computer Ready) ‘bb’ Data Write Data Reset DTR (End of File) DSR

PDACS 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.

PDACS GUI Decompresses sound files through software, output to a.wav file Allows user to play a audio file through the Windows multimedia player.

PDACS System Integration Memory to Serial Integration Audio to Memory Audio to Codec Codec to Memory Serial to GUI

PDACS

PDACS 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

PDACS 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

PDACS What We Dropped Portability Power Subsystem Completely Integrated Finished Product Real-time compression & decompression of audio

PDACS And Remember… Xilinx is cool, but it’s occasionally bogus. -Scott