The Xiao ESP32 runs a tiny web server that serves an interactive piano keyboard to any browser on your WiFi network. When you tap a key (or press a keyboard key), the browser sends an HTTP request to the ESP32, which generates a sine wave at the correct frequency and pumps it out through the I2S bus to the MAX98357 amplifier.
Features:
- Web UI — A full 25-key piano rendered in HTML/CSS with both tap/click and physical keyboard support
- I2S Sine Wave Generator — Real-time sine wave synthesis at 22.05 kHz, 16-bit stereo
- Auto-Play Engine — 5 built-in songs (Twinkle Twinkle, Ode to Joy, Happy Birthday, Jingle Bells, Fur Elise) with a sequencer that chains songs randomly
- OLED Status — Shows IP address, current note/frequency, and auto-play song name
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1. Hardware Connection:
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2.Install Arduino IDE Libraries
Open Tools → Manage Libraries and install:
- Adafruit SSD1306 (by Adafruit)
- Adafruit GFX Library (by Adafruit)
The `WiFi.h`, `WebServer.h`, `Wire.h`, and `driver/i2s.h` libraries are built into the ESP32 Arduino core — no extra install needed.
3. Select Your Board
Go to Tools → Board → Boards Manager, search for “Seeed Xiao ESP32”, and install the board package.
Then select:
- Board:Seeed Studio XIAO ESP32S3
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- Port:(the COM port for your Xiao)
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4. Configure WiFi
Open `xiao_piano.ino` and edit lines 17–18:``cpp
const char* WIFI_SSID = “YOUR_WIFI_SSID”;
const char* WIFI_PASS = “YOUR_WIFI_PASSWORD”;
Use 2.4GHz only — ESP32 does not support 5GHz WiFi.
5.Upload
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Click Upload (→). Open Tools → Serial Monitor at 115200 baud. You should see:
The OLED will also display the IP address. Open that URL in any browser on the same WiFi network.
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WiFi connecting…
WiFi OK — IP: 192.168.1.42
=== Piano ready ===
Open http://192.168.1.42 in your browser
The OLED displays the IP address. Open it in any browser on the same WiFi network.
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6. How to Play
Manual Mode
Tap or click any key on the piano. Or use your keyboard:
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Tip: If keyboard stops working, click anywhere on the page to give it focus.
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Auto-Play Mode
Below the piano you’ll see three controls:
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- Random (green) — Plays a random song from the library
- Song picker dropdown — Choose: Twinkle Twinkle, Ode to Joy, Happy Birthday, Jingle Bells, Fur Elise
- Stop (orange) — Stops auto-play
When one song ends, a different random song starts automatically — it’s a self-playing piano. The OLED shows the current song name and notes. Tap any key to exit auto-play and return to manual mode.
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Conclusion
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A single .ino file, you get a WiFi piano you can play from any phone, tablet, or laptop in your house. The auto-play mode with 5 built-in songs means it doubles as a self-playing music box. It’s a fun weekend build that covers I2S audio, I2C displays, WiFi web serving, and real-time synthesis — all on a thumb-sized Xiao ESP32.
