Bluetooth Classic Serial Port Profile (SPP) — RFCOMM byte streams.
Use this for legacy serial-over-Bluetooth devices: Arduino HC-05/HC-06 modules, OBD-II ELM327 readers, marine GPS pucks, industrial sensors, legacy barcode scanners, etc. Anything that exposes itself as a bidirectional byte pipe over a custom RFCOMM channel UUID.
See MobBluetooth for pairing, discovery, and disconnect.
Typical flow
# 1. Pair (MobBluetooth.pair/2)
# 2. Connect SPP, supplying the RFCOMM service UUID.
# The well-known SPP UUID is "00001101-0000-1000-8000-00805F9B34FB".
socket = MobBluetooth.Spp.connect(socket, device,
uuid: "00001101-0000-1000-8000-00805F9B34FB")
# {:bt_spp, :connected, session_id, payload}
# 3. Receive bytes:
# {:bt_spp, :data, session_id, bytes}
# 4. Send bytes:
MobBluetooth.Spp.write(socket, session_id, "ATZ\r\n")
# 5. Disconnect (MobBluetooth.disconnect/2)UUIDs
Most SPP devices advertise the standard SPP UUID
00001101-0000-1000-8000-00805F9B34FB. Some manufacturers use custom
UUIDs to scope to a specific protocol on the same physical device.
Pass via the :uuid opt; if omitted, the standard SPP UUID is used.
Insecure RFCOMM
By default the connection uses the secure RFCOMM channel (encrypted,
requires bond). Some legacy devices (especially HC-06 clones) only
accept insecure RFCOMM. Pass secure: false to fall back.
Summary
Functions
@spec connect(socket :: term(), MobBluetooth.device(), keyword()) :: term()
Open an SPP (RFCOMM) connection to device.
Options
:uuid— RFCOMM service UUID (default:"00001101-0000-1000-8000-00805F9B34FB"):secure—true(default, encrypted) orfalse(legacy insecure)
Result: {:bt_spp, :connected, session_id, payload} on success,
{:bt_spp, :connect_failed, %{address: String.t(), reason: atom()}}
on failure (3-tuple — no session id exists yet).
@spec write(socket :: term(), MobBluetooth.session_id(), binary()) :: term()
Write a byte payload to the SPP session.
Returns the socket. Fire-and-forget: bytes are queued in Kotlin's output stream and flushed asynchronously. No completion event.
Errors during write are surfaced as
{:bt_spp, :disconnected, session_id, reason} (Kotlin closes the
socket on write failure).