Embedded design of audio acquisition system

Project (M.S., Electrical and Electronic Engineering) -- California State University, Sacramento, 2011.The audio processing is of great importance in today???s world of portable mobile \ud devices for large data storage. The purpose of the project is to record an audio data, store \ud it in a memory storage device, and then retrieve it for later use. This will aid audio \ud processing in its verification on hardware if data are processed before and after storing. \ud Embedded design includes collecting audio data from a microphone and capturing it \ud in an AVR microcontroller using an embedded Analog to Digital Converter (ADC) and \ud an external preamplifier. Then, sampled data are stored in a flash memory. Stored data \ud are then used for playback through the speakers. The Pulse Width Modulation (PWM) \ud was used as a Digital to Analog Converter (DAC) for converting digital data into analog \ud signal, followed by a filter and an amplifier for driving speakers. \ud The project was implemented on an Atmel Corporation STK500 kit along with an \ud AVR microcontroller. The required ADC and PWM logic were available in the AVR \ud microcontroller. Serial Peripheral Interface (SPI) was also a feature the AVR v \ud microcontroller. It was used to interface a flash with an AVR microcontroller. The filter \ud circuit and the amplifier circuit for the microphone were designed using operational \ud amplifiers LM358 and LM324.Electrical and Electronic Engineerin