EE 552 High Level ASIC Design Using CAD

EE 552 High Level ASIC Design Using CAD Tools Digital Theremin Farooq Ahmad Alesya Bajoria Tim Church Nicolas Lauzon Albert Ma Celia Valel

Introduction t t t Traditional Theremin is a musical instrument invented in 1919 by Russian physicist Lev Termen. Two antennas protrude from the Theremin – they use a variable capacitance to measure the proximity of the musician’s hands. Approaching vertical antenna increases pitch while horizontal antenna controls volume.

Objective Our goal is the development of a digital instrument that can be played without direct contact. § VHDL and the XSA-100 Spartan-II Prototyping Board with XST-1 Xstend Protyping Extender Board were used. § IR sensors measured the distance of the musician’s hands from the instrument.

Features t Hands can be moved t Switches allow selection from 10 cm to 80 cm from the sensors for volume and pitch control. t Minimum frequency of 980 Hz and maximum frequency of 2. 9 k. Hz. t Switch allows the musician to sustain a particular pitch. from various wave shapes:

Design Composed of three main components: 1. Input Interface 2. Numerically Controlled Oscillator 3. Output Interface Sustain Frequency Switch MC 33172 P Operational Amplifier GP 2 YOA 21 YK Distance Measuring Sensor (pitch) ADC 974 Analog to Digital Converter (16 -bit) Input Interface (serial-parallel conversion, ADC control) Phase Accumulator Look Up Table (for frequency/ wave shape) selection GP 2 YOA 21 YK Distance Measuring Sensor (volume) ADC 974 Analog to Digital Converter (16 -bit) MC 33172 P Operational Amplifier Input Interface XSA-100 Spartan-II Prototyping Board Volume Modulator Output Interface (parallel-serial conversion, Codec control) 20 -bit stereo audio codec (serial-parallel conversion, ADC control) Wave Shape Selector to speaker

Input Interface MC 33172 P Operational Amplifier t Op-amp reduces loading. Input Interface t Analog Devices AD 974, converts analog output from the distance sensor to 16 -bit serial data stream. t VHDL module controls t Sharp GP 2 Y 0 A 21 YK distance sensors measure - ADC and converts its serial output to a parallel data proximity of hand by output vector to be used by the of voltage from 2. 5 V to 0. 4 numerically controlled V as an object moves from oscillator. 10 cm to 80 cm from it. GP 2 YOA 21 YK Distance Measuring Sensor ADC 974 Analog to Digital Converter (16 -bit) (serial-parallel conversion, ADC control)

§ Nonlinear output of distance measuring sensor was linearized using a VHDL module.

Numerically Controlled Oscillator t t This component is responsible for outputting a sine, square, triangle or sawtooth wave of a frequency and amplitude controlled by the output of the IR sensors. It consists of a: o Phase accumulator o Wave look up table o Volume modulator

Phase Accumulator t The first stage of the NCO is a phase accumulator, which produces an output dependent on a parallel data word (proportional to the desired pitch) from the IR sensor. t A counter is increased in increments of this word, and wraps around every time it overflows. The numbers in the counter correspond to the phase of a sine wave increasing from 0 to 2*pi. The resulting wave shape is a wave with a frequency of fout = fclk x FCW/2 j where fclk = the clock frequency, FCW = frequency control word from the IR sensor and j = size of frequency control word.

Wave Look-Up Table t t The wave look up table will contain a single phase of each of the sine, sawtooth, triangle and square waves. These values, which are stored for the use of the NCO, will be done so on the 40 kbits of block RAM.

Volume Multiplier t t The output from the distance measuring sensor responsible for volume control will be sent to a multiplier. In this way, the amplitude of the output signal will be modified.

Output Interface From NCO Output Interface (parallel-serial conversion, Codec control) 20 -bit stereo audio codec To speaker § The 16 -bit parallel output from the volume modulator is converted into serial data. § This serial data will be fed to the 20 -bit stereo codec which is present on the XST 2 XStend board. § The audio codec accepts the serial bit stream from the XS board and converts it to two analog output signals. § The signals are fed into an amplifier and output through a speaker.

Conclusions t. This project has been successful in introducing a modern twist to an instrument that is had an eightyfive year life span.