Mini-Mixer

Project Details

Title: Mini-Mixer

Class: Low Power Embedded Design Techniques

Semester: Fall 2020

Team: Atharva Nandanwar, Jiabin Lin, Mike Fruge

Project Overview

This project, named the Mini Mixer, is a system designed to send MIDI inputs from a windows application to the control board which generates modified musical waveforms using the MIDI inputs. This device is designed to be portable and battery powered, allowing the user to bring the device wherever they need it. Mini Mixer also provides an alternate power supply option from the USB. When both USB and battery are plugged into the system, the USB will act as the power supply for the system and charge the battery if the battery is lower than the threshold.

The device plugs into a speaker via AUX cord, allowing the user to play, alter and mix musical notes in front of a crowd. The system provides users musical effects such as reverb, change 128 instruments, pitch bend and LEDs control.

User can connect the device via bluetooth to the computer and choose input and output source from the MIDI berry windows application. The input source can be the physical keyboard or the MIDI berry application itself.

The value in this project lies within the ability to remix songs you and your friends love. When you feel inspired, grab the Mini Mixer, plug it into a speaker, play musical notes from the keyboard or MIDIBerry windows application, and add energy to any gathering. Mini Mixer is a portable and battery-driven mixer, users can mix music everywhere and anytime.

Video Demo

Project Block Diagram

This system consists of PMIC, MCU, and Codec three main modules.

PMIC module’s main responsibility is to support power to the entire system.

• It decides whether the system will be powered by battery or USB

• It provides both 3.3V and 1.8 V power supply the system

• It charges battery when the battery is plug in and the battery voltage is less than 4.2V

• When use battery as the power source, it will stop the battery from being drained if the battery voltage source is less than 3.3 V

MCU module handles the bluetooth request, handles external signals from the either encoders or capacitive sensor and then sends MIDI command to the Codec module. It also does energy mode control to save the system energy, initialized and controls the PMIC module.

The Codec module received the command from the MCU and output generated the analog signal to the aux cable and will eventually get connected to the audio output.

Software Block Diagram

PCB Layout