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The LM068 BLE Adapter is a device designed to facilitate serial communication over Bluetooth Low Energy (BLE). It functions as a GAP peripheral device, meaning it can accept connections from Android, iOS, or any GAP-Central device. The adapter provides a standard DB9 connector for its serial interface and can be powered via a mini USB port or pin 9 of the DB9 connector. A DTE/DCE selection switch allows users to configure the adapter's role in the serial communication. The device also features LEDs to indicate various operational states.
The LM068 BLE Adapter, running firmware LM068_BLE_Peri_0201 (or later versions like LM961_LE_Peri_0204 and LM961_LE_Peri_0205), acts as a BLE peripheral. It initializes its GATT database and begins advertising itself for connections upon power-on. The adapter uses its static and public Bluetooth Device (BD) address for advertising, ensuring a consistent address across advertisements. A short name, "LM068BLE," is included in the scan response data, and the full device name can be read via the Generic Access service after a connection is established.
As a GAP-Peripheral device, the LM068 implements a database for Generic Access Service (0x1800), Generic Attribute Service (0x1801), and Serial-Over-GATT Service. The 128-bit UUID of the Serial-Over-GATT service is advertised as "0000-5501-d102-11e1-9b23-0002-5b00-a5a5". Advertising filters can be applied based on the LESEC configuration for BLE security, allowing connections only from whitelisted devices.
Once a BLE connection request is received, the adapter accepts it and initiates a pairing procedure if the device has not been previously paired. If pairing fails, the connection is dropped. After a successful connection, data transmission occurs via the Serial-Over-GATT service. The GAP central device sends data to the BLE adapter using "Write-WO-Response" commands, and the BLE adapter sends data to the GAP-Central device using "Notifications" requests. For active data transmission, the GAP-Central device must enable the Client-Configuration-Flag on the BLE adapter.
The adapter supports full-duplex data transfer. When the BLE adapter receives data on its UART (intended for the GAP-Central), it sends the data in 20-byte packets every 50mSec. It has an internal buffer of 200 bytes for storing data. If this buffer becomes full while the adapter is still receiving data on the TX line, a "Buffer full" warning message is issued. Data received from the Central device is uploaded to the Rx line immediately. While full-duplex transmission may experience some delays compared to simplex transfer, it is crucial to introduce a delay of at least 10 mSec between consecutive packets sent by the central device to prevent the BLE adapter from hanging up.
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AT*ADDR=? for Bluetooth address, AT*NAME=? for device name, AT*VER=? for firmware version, AT*SETTINGS=? for all settings).AT*NAME=testname to change the device name, AT*UPDATENAME=ON/OFF to enable/disable appending BD address characters to the name, AT*ECHO=on/off for command echo, AT*RESP=on/off for command response).AT*RESET=1 for soft reset, AT*RESET=2 for hard reset and factory defaults, AT*CLRWHITE to clear the whitelist, AT*UPGRADE to enter firmware upgrade mode).AT*BAUD=3 for 38400 bps). Default is 19200 bps.AT*PAR=1 for odd parity). Default is no parity.AT*STOP=1 for two stop bits). Default is one stop bit.AT*FLOW=ON). Default is OFF.AT*LESEC=ON/OFF to enable/disable whitelist security. When ON, only whitelisted devices can scan advertisements and connect. When OFF, any GAP-Central device can connect.AT*LEBOND=? to query the bonded device address. AT*LEBOND=address to set the bonded device address. If set to 0000-00-000000, the adapter is not bonded and accepts connections from any device.AT*Reset=1 or AT*Reset=2.AT*UPDATENAME feature appends the last two characters of the BD address to the Bluetooth name to differentiate multiple LM devices in close proximity.UARTCONF setting must be set to "THROUGHPUT" for successful upgrade.AT*UPGRADE=LMUPDATEV_LM068_BLE_Peri_0201 (password-dependent on device type and firmware version) puts the device into upgrade mode.AT*RESET=1): Restarts the device as if power cycled, retaining all user-modified settings and disconnecting all Bluetooth/BLE connections.AT*RESET=2): Applies factory default settings, deletes all paired devices and corresponding data, and disconnects all Bluetooth/BLE connections.
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