PIC16F877 Based Digital Effects Pedal

Overview

The purpose of this project is to record guitar sound to RAM and perform mixing or other manipulations with real signal on the output through op-amp.

Details

The digital effects pedal is built around the PIC16F877 microcontroller as it stores sound on the 256kb of RAM. With the help of a relay, the unit achieves true bypass as it runs on a standard 9V power supply. The relay is disengaged when the circuit is powered OFF where the signal is fully bypassed  with most of the signal coming directly to the output although some part of it is amplified through the op-amp and sent to the PIC for ADC processing.

The ADC values are transmitted to the 23k256 for temporary storage using the continuous write mode when the system goes into record mode where any data available will be overwritten. The relay gets engaged when the system switches back into playback mode. The amplifier is used to transmit the audio from the guitar if the byp/kill switch is in byp mode, or will be silenced otherwise. The 23k256 rapidly reads data which is outputted to DAC. No amplification is needed on the resulting signal.