CLUE ble beacon remote

CLUE_BLE_Beacon_Remote/ble_transmitter.py

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+# SPDX-FileCopyrightText: 2026 Pedro Ruiz for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+'''MagicBand+ BLE transmitter for the Adafruit CLUE.
+
+Wraps _bleio.adapter to broadcast raw advertisement packets with Disney's
+0x0183 manufacturer company identifier. Works directly with the BLE stack
+on the nRF52840 without going through adafruit_ble's Advertisement classes.
+'''
+# Target: Adafruit CLUE (nRF52840) - the BLE remote
+import time
+import _bleio
+
+from magicband_protocol import DISNEY_CID
+
+# BLE advertising interval in seconds. CircuitPython requires this to be
+# in the range 0.02-10.24. We use 0.025 instead of 0.02 because float
+# precision can cause 0.02 to internally evaluate as slightly less than
+# the minimum, raising "interval must be in range" ValueError.
+_AD_INTERVAL = 0.025
+
+# Default broadcast duration. MagicBands latch a command within the first
+# ~second, but the timing byte in the payload controls the actual fade so
+# we can stop advertising well before the animation finishes.
+_BROADCAST_SECONDS = 3.0
+
+
+def _build_advertisement(payload):
+    '''Assemble a 31-byte BLE advertisement packet with Disney manufacturer data.'''
+    cid_lo = DISNEY_CID & 0xFF
+    cid_hi = (DISNEY_CID >> 8) & 0xFF
+    mfr_field_len = 3 + len(payload)
+    return bytes((
+        0x02, 0x01, 0x06,                      # Flags AD: LE General Discoverable
+        mfr_field_len, 0xFF, cid_lo, cid_hi,   # Manufacturer data header
+    )) + payload
+
+
+def broadcast(payload, duration=_BROADCAST_SECONDS):
+    '''Advertise a MagicBand+ manufacturer-data payload for duration seconds.'''
+    packet = _build_advertisement(payload)
+    adapter = _bleio.adapter
+    if not adapter.enabled:
+        adapter.enabled = True
+    if adapter.advertising:
+        adapter.stop_advertising()
+    adapter.start_advertising(packet, connectable=False, interval=_AD_INTERVAL)
+    time.sleep(duration)
+    adapter.stop_advertising()

CLUE_BLE_Beacon_Remote/boot.py

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+# SPDX-FileCopyrightText: 2026 Pedro Ruiz for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+'''CLUE boot configuration: optional Python-writable filesystem.
+
+CircuitPython by default mounts CIRCUITPY as read-only when USB is
+connected, so Python can't write files. To capture BLE packets to a
+file (Listen Mode in code.py) while USB is connected, we need to flip
+that.
+
+Two ways to enter capture mode:
+
+1. **Marker file**: drop a file named `capture_mode.txt` onto the
+   CIRCUITPY drive while USB is connected, then reset. boot.py sees
+   the marker and remounts the filesystem as Python-writable.
+
+2. **NVM flag**: code.py can request "next boot in capture mode" via
+   a byte in microcontroller.nvm. This survives reboots and works
+   regardless of who currently owns the filesystem. boot.py also
+   creates the marker file in this case so the user can see the
+   mode is engaged.
+
+To exit capture mode: open the REPL and run
+    import os; os.remove("/capture_mode.txt")
+then reset. The filesystem returns to host-writable.
+'''
+# Target: Adafruit CLUE (nRF52840) - the BLE remote
+import os
+import storage
+import microcontroller
+
+_MARKER = "/capture_mode.txt"
+_NVM_FLAG_BYTE = 0  # NVM byte 0: 1 = request capture mode on this boot
+
+marker_present = False
+try:
+    os.stat(_MARKER)
+    marker_present = True
+except OSError:
+    pass
+
+# NVM-requested capture mode: code.py wrote 1 to byte 0 to ask for
+# capture mode on this boot. Honor it by remounting writable and
+# creating the marker file (which clears the NVM flag for next time).
+nvm_request = microcontroller.nvm[_NVM_FLAG_BYTE] == 1
+
+if marker_present:
+    storage.remount("/", readonly=False)
+    print("[boot] Capture mode (marker file present)")
+elif nvm_request:
+    storage.remount("/", readonly=False)
+    # Create the marker file so user can SEE that capture mode is active.
+    # Content includes the literal REPL commands to undo it - paste-ready
+    # without leading whitespace, so users who open the file in any text
+    # editor can copy/paste directly into the serial REPL.
+    try:
+        with open(_MARKER, "w", encoding="utf-8") as f:
+            f.write(
+                "Capture mode active.\n"
+                "This file makes CIRCUITPY Python-writable so Listen Mode\n"
+                "can save captures. While this file exists, you CANNOT\n"
+                "drag-drop new code onto the drive.\n"
+                "\n"
+                "To return to dev mode (drag-drop), open the serial REPL,\n"
+                "press Ctrl+C to interrupt, then paste these lines:\n"
+                "\n"
+                "import os\n"
+                "os.remove(\"/capture_mode.txt\")\n"
+                "\n"
+                "Then reset the CLUE.\n"
+            )
+        # Clear the NVM flag - we honored it
+        microcontroller.nvm[_NVM_FLAG_BYTE] = 0
+        print("[boot] Capture mode (NVM-requested, marker created)")
+    except OSError as err:
+        print(f"[boot] Capture mode requested but write failed: {err}")
+else:
+    print("[boot] Dev mode: USB host has filesystem write access")