Digital Audio Processor

1. Digital Audio Processor William Buttinger and Dimitri Podoliev

2. Project Overview • Highly customizable digital audio system • Provide pre-built effects packages with user-specifiable parameters • Use audio “building blocks” with the packages to create unique effects • Use a computer to configure the processor

3. Overall Block Diagram Module1 Module2 ModuleN … Signal_out1 Signal_outN parameters1 parametersN 18 18 18 18 Signal_in1 Signal_inN input1 Analog_In1 Input1 Interconnect Architecture RS232 reprogram computer Reprogram Controller params1 Analog_In2 Input2 . . inputN Analog_InN InputN paramsN 18 18 18 18 right_out Left_out right_in Left_in Codec Controller SDATA_IN SDATA_OUT Bit_clock AC97 To all modules

4. Interconnect Architecture … • Asynchronous Interconnect • Router provides most flexibility … … … • Reprogramming done by • synchronized FSM. • Control Bit controls a tristate buffer Control bit

5. Modules Module Name Parameters Delay Duration, Level, Feedback Band Pass Central Frequency, Width Compressor Threshold, Ratio, Attack time, Release Time Expander Threshold, Ratio, Attack time, Release Time Mixer - Multiplier Co-efficient ……..More?

6. Theoretical Implementation of FiltersSignal Processing • Digital filters implementation: • IIR (Infinite Impulse Response) • FIR (Finite Impulse Response) • Design Path of an IIR filter: • Bode plot • Transfer Function • Impulse Response • Z-transform • Difference equation • Verilog implementation using modular blocks

7. Implementation of a single pole Low Pass Filter • Transfer function: • Difference equation: • Implementation diagram: • Other filters, such as: • High Pass • Band Pass • Band Reject • Can be easily implemented using this building block

8. Design of a Simple Phaser

9. Routing of a Simple Phaser Filter

10. Questions?