Published on Dec 31, 2019 Ryo Kosaka
https://github.com/RyoKosaka/HelloDru...
Features
Single piezo pad, Dual Piezo pad, 2 zone cymbal, 3 zone cymbal
Compatible with YAMAHA's 3 zone cymbal(PCY135/PCY155)
Compatible with SoftPot, FSR and Optical(TCRT5000) type hi-hat controllers
Sensing with MUX(4051 and 4067)
Setting mode with LCD or OLED
Sensitivity, Threshold, Scan Time, Mask Time, Note Number can be set with each pad
Works with ESP32 and Teensy and AVR boards such as UNO and MEGA.
https://open-e-drums.com
"open e-drums" is a completely open source electronic drum. Pads that can be produced with 3D printers, and midi converters are all open source hardware. Arduino code for sensing is also available. You can create your own e-drum from scratch, or add pads to the Roland and YAMAHA kits.

This project started by accident. At the time, I was a product design student who had used Arduino just a little. When I found a drum mania controller at a used store at a bargain price, I was somehow attracted to it and bought it. This is the beginning of everything. I took it apart and played with Arduino. I used a piezo for the first time at that time. I learned the delicate sensing ability of piezo. I realized the greatness of electronic drums such as Roland, Yamaha, and Alesis, which process the signals beautifully. I want to try it myself.
I didn't have any knowledge of programming or electronics. In other words, I have acquired a lot of knowledge through this project. For some people, this project is just a reinvention of the wheel. But it's a very meaningful project for me. As I proceeded with this project, I drew on the knowledge of many predecessors. Many of them keep information open. That's great. So I decided to publish this project as an open source hardware project. I would be happy if this project helps someone create something."