ECE 477 Digital Systems Senior Design Project Fall 2004

Homework 3: Final Design Project Proposal

Due: Thursday, September 16, at Classtime

Team Code Name: SyNtHmAsTeRz of DoOm!!!1~ Group No. 3

Team Members (#1 is Team Leader):

#1: Jeff Wenger Signature: ______Date: ______

#2: Ben Henry Signature: ______Date: ______

#3: Jason Baumann Signature: ______Date: ______

#4: Arjun Swarup Signature: ______Date: ______

Abstract:

This group is creating a synthesizer that receives MIDI commands and uses them to generate a signal composed of three types of waveforms and outputs that signal to a D/A. The analog signal is then filtered though user-controllable low-pass and high-pass filters, amplified, and output to speakers.

Design Objectives:

·  The MIDI interface should be able to correctly interpret MIDI control signals according to the MIDI specification.

·  Waveforms should be generated according to the MIDI signals received.

·  Audio should be clean and free of undesired artifacts.

·  The device should be packed in an aesthetically pleasing and efficient manner.

·  Filters should operate according to digitally controlled potentiometers.

·  Waveforms will be generated by using wave-table lookup.

·  Multiple waveforms should be mixed cleanly to produce one output.

·  A D/A should receive parallel 12-bit data from the microcontroller and output an analog signal.

·  No fires.

Design/Functionality Overview:

The user will input a sound request using a MIDI-compatible device. The sound requests specify a tone at a desired frequency, but there will also be parameters for controlling the filters. A total of three waves will be mixed together in the 68HCS12. The user will have the ability to select between triangle, square, and sine waves for each waveform to be mixed. Other parameters that the user can control will include ADSR, frequency, and amplitude. These MIDI commands will then be decoded and used to mix three waveforms together in the 68HCS12. The resulting waveform will then be sent to an output buffer where it will be ADSR scaled while it is being sent to the D/A converter at timed intervals. The analog signal coming out of the D/A will then pass through user-controllable low-pass and high-pass filters. The signal will then be amplified and sent to the speaker for listener enjoyment!

Project-Specific Success Criteria (list 5):

·  An ability to interpret MIDI control signals.

·  An ability to perform wavetable lookup in a 68HCS12.

·  An ability to mix multiple waves in the 68HCS12.

·  An ability to filter the waveforms according to user input.

·  An ability to output parallel data to a D/A converter and have it output an analog signal.

Software Module List:

·  SPI Interface with Digital Potentiometers

·  MIDI Command Interpretation

·  Waveform Generation

·  Low-Pass and High-Pass Filter Control

·  ADSR Filtering

·  Waveform Mixing

Division of Labor:

Design Component Homework / Professional Component Homework
Packaging Design and Specs / Jeff Wenger / Design Constraint Analysis/Parts List / Jeff Wenger
Circuit Schematic and Narrative / Ben Henry / Patent Liability Analysis / Ben Henry
Board Layout / Jason Baumann / Reliability and Safety Analysis / Jason Baumann
Software and Narrative / Arjun Swarup / Social/Political/Environmental Analysis / Arjun Swarup

Hardware Block Diagram: