Sound Effects Processor Controlled by AVR

The project aims to amplify an input signal by building an input stage which will also bias the sample positive signals by ADC to 2.5V.

The microprocessor Mega32 controls the ADC MAX1111 with the use of SPI interface making it much easier than manually configuring a port to interface with the ADC. To meet the requirement for analog to digital sampling, the Mega32 was set to sample the input at about 12kHz which is fast enough. By manipulating the input, the digital effects were done and the output is passed to R-2R DAC to an output amplifier stage while the speaker is the final destination.

During the process, the audio input goes through an amplification and bias stage and then flows through the ADC that is being controlled by the microcontroller via the SPI. At about 12,000 samples per second, the input is sampled with 6kHz which covers most of the frequency content of the expected audio signal. The input is stored by the microcontroller in an array and sends the output through the Port D to the DAC while the buttons for user input are polled. Effects are displayed on LCD.

Rest of the project