01 Overview

EDA-Piano is an ESP8266-based 12-key touch piano project designed for low cost and easy learning.

Core components are the ESP8266 module and the SC12B touch controller; the TP4056 charger is optional.

It supports simultaneous 12-key detection, chord playing, real-time OLED feedback, and WiFi-based web control.

It replaces mechanical keys with touch electrodes, simplifying assembly and reducing cost.

Ideal for electronics courses, maker education, and music introduction; also a prototype for IoT audio interaction.

It is not a professional instrument—the buzzer produces simple tones—but it demonstrates touch sensing, chord logic, and IoT control.

02 Hardware

MCU: ESP8266 module, providing WiFi and GPIO interfaces.

Touch sensing: SC12B chip, communicates via I2C, supports 12-key simultaneous detection with high accuracy for chords.

Audio output: buzzer driven via PWM or GPIO; for richer tones, an I2S DAC and speaker can be added (extra circuitry required).

Display: OLED screen (I2C interface, e.g., SSD1306) showing current keys and note information.

Power: TP4056 Li-ion charging module (optional), provides charging and protection for 3.7V Li-ion; if removed, use USB 5V directly.

Touch electrodes: 12 copper pads on PCB, routed to SC12B inputs; layout must avoid interference.

Total BOM cost is low, dominated by the ESP8266 and SC12B.

03 Software flow

Flash firmware: use Arduino IDE or ESP-IDF, select ESP8266 board, verify GPIO assignments before flashing.

Initialize: power-on, init I2C (for SC12B and OLED), configure WiFi (STA or SoftAP).

Touch scan: periodically read SC12B key state registers to detect presses and releases.

Chord logic: based on simultaneous key combinations, generate note frequencies and output via PWM to buzzer.

OLED display: update current keys and note names, show chord type (e.g., C major, Am).

Web control: start HTTP server, provide web page to remotely view key states or trigger notes.

Error handling: if WiFi fails, enter AP mode; if touch chip unresponsive, retry I2C communication.

Low power: optional sleep mode, enter deep sleep when idle, wake on touch (requires hardware support).

04 Core points

SC12B I2C address and register map must be checked in the datasheet; minor variations may exist.

Touch electrode layout affects sensitivity; follow SC12B design guidelines, avoid long or parallel traces.

Buzzer tone is simple; for multi-timbre or chord mixing, use I2S DAC and amplifier.

WiFi communication may introduce latency; for real-time play, reduce web polling or disable it.

TP4056 charging module requires battery protection; if removed, ensure stable power supply.

ESP8266 has limited ADC pins; for additional analog inputs, watch pin multiplexing.