Overview

Our board was intended to be a MIDI board using the ESP32 microcontroller, integrated 26 capacitive touch switches for seamless input functionality. We designed via KiCad and incorporated multiplexers to effectively reduce pin usage while maintaining high responsiveness. Wrote and debugged firmware to enable MIDI signal transmission and compatibility with digital audio workstations (DAWs). This project demonstrated expertise in embedded systems design, hardware-software integration, and creative problem-solving in a music technology context

Features

Power

• 5V USB-C 

• LDO to step down 5 to 3.3 for ESP32

Actuation

• 23 Switches all connected to varying pins on two different's multiplexer which connect to ESP32

  • Each switch is intended to be programmable as to whatever the user desires, i.e. piano keys, drum sounds, etc

• 3 different potentiometer's intended to control bass, treble and overall volume when board is connected to MIDI_Out

Sensing

• 4 Drum Pad sensors that are meant to take physical touch input and be connected to ADC pin on ESP32

  • Each pad is also programmable to make whichever different sound as user chooses

Connection options

• DIN connectors for industry standard speakers

• ESP32 plus wifi and bluetooth allow us to connect to a speaker and then remotely control custom website

Layout

Bringup

Things We Would Improve + Important Learnings

• Learnings 

  • Follow and recheck datasheets for ICs (specifically we messed up on the buck converter and the DAC, resulting in overall problems for our ESP32)

  • Placement of components is very important for layout (for example, we didn't consider that the USB-C receptacle should be close to the edge of the board so we had to end up cutting the PCB) 

  • Double check to make sure indicating components (such as LEDs) are properly connected, so we have a way of testing if the board works 

    • Also include better testing points for continuity and power throughout the board (for troubleshooting) 

• Things we would improve

  • Buck converter would be replaced and properly routed

    • Tried using an LDO but the component wouldn't step down to 3.3 V 

  • Fix traces from the DAC 

  • Work in steps (try smaller goals) 

    • start off with keys, then drum pads, etc.

  • Get things done early to have time for bringup and validation