E155 Project Portfolio

Abstract

This project implements a digital guitar pedal capable of applying a real-time chorus effect to an instrument input. The system utilizes a hybrid architecture featuring a microcontroller (MCU), an FPGA, an external DAC, and custom analog circuitry. The analog front-end passes the guitar input through gain scaling and offset adjustment, followed by 4th-order anti-aliasing filters. The signal is then digitized by the MCU’s internal ADC and transferred via DMA to an SAI module for output in I2S format.

The FPGA decodes the incoming I2S data and routes it to a DSP module, which utilizes SRAM to generate the chorus modulation. Finally, the processed audio is packaged and transmitted out to an external DAC via I2S, converted back to an analog signal, and scaled to a safe output range suitable for a standard guitar amplifier.

Final Project picture

Figure 1: Final project in its enclosure

Video Demonstration

Block Diagram

Acknowledgements

As a team we want to thank Prof. Spencer for providing valuable feedback on all our submitted assignments to help us form better code writing habits. We also want to thank Xavier for helping us with debugging on the circuit.