BabyMobile Audio Manager (PWA)

A dependency-free, client-side web app that scans for the BabyMobile XIAO (nRF52840) over Bluetooth LE and manages the audio files on it. No backend, no build step, nothing leaves your device — all audio conversion happens in the browser with the Web Audio API.

Pairs with the firmware in ../baby_mobile_v2/baby_mobile_v2.ino.

What it does

Scan & connect to the BabyMobile BLE peripheral.
Convert any browser-decodable file (WAV/MP3/M4A/OGG/FLAC…) to a conformant mono PCM WAV — 8-bit / 8 kHz by default, with 8/16-bit and 8/16/32 kHz selectable. The full WAV (44-byte header + data) is streamed intact; the firmware self-configures bit depth and sample rate from the header.
Upload to any of the 32 track slots, with a live progress bar driven by the device's status-notification byte count.
Play / stop any slot.
Remember what you uploaded per browser (localStorage), since the firmware exposes no track-listing command over BLE.

BLE protocol used

	UUID	Use
Service	`12340001-…`	advertised
Cmd (write)	`12340002-…`	`0x02 <slot>` start upload · `0x03` finish · `0x04 <slot>` play · `0x05` stop · `0x06` list · `0x07 <slot>` delete
Data (write-without-response)	`12340003-…`	raw WAV bytes, chunked to 180 B
Status (notify)	`12340004-…`	tagged by byte 0: `0x00…` upload byte count (uint32 BE) · `0x80\|idx, bits, kHz, secs` list entry · `0xFF, n` list end · `0xD0, idx, ok` delete reply

Running it

Web Bluetooth requires a secure context: https:// or http://localhost.

# from this app/ directory — any static server works
python -m http.server 8000
#   then open  http://localhost:8000

Deploy the folder as-is to any static host (GitHub Pages, Netlify, Cloudflare Pages…) to install it as a PWA from a phone. It's a complete app shell with a service worker, so it also launches offline once cached.

Platform support

Platform	BLE works?	How
Android	✅	Chrome or Edge; "Add to Home screen" installs the PWA
Windows / macOS / Linux	✅	Chrome or Edge
iPhone / iPad	⚠️ via Bluefy	iOS Safari/WebKit has no Web Bluetooth

iOS setup (no App Store)

Apple doesn't ship Web Bluetooth, so a plain Safari PWA can't reach BLE. Use the free Bluefy – Web BLE Browser: open this app's URL inside Bluefy and everything works. (Bluefy itself is the only App Store install needed — the app stays a web app.)

If you later want a true installable iOS app without Bluefy, wrap this same folder in Capacitor with @capacitor-community/bluetooth-le and reuse ble.js's protocol constants.

Notes & limits

Flash size: the firmware's POC stores tracks in the nRF52840's internal LittleFS, which is small. 8-bit/8 kHz ≈ 8 KB per second of audio — keep clips short. If the device acknowledges fewer bytes than sent, the app warns you (flash likely full).
Listing & delete are live: on connect (and after every upload/delete) the app sends 0x06 to read the device's real track table, and 0x07 deletes a slot on the device. Track titles aren't stored on the device, so they're remembered locally and shown next to the live entries; an uploaded slot with no local name just shows "Track N".
MTU: data is chunked to 180 bytes to stay within a modest negotiated ATT MTU (firmware char max is 240).

3.5 KiB Raw Blame History Unescape Escape