NINA-B31 series - Getting Started
UBX-18022394 - R02
Configuration
Page 12 of 26
2.8
Bluetooth security
There are six different security modes that support all kinds of use cases regarding the pairing
procedure.
All security modes use encryption. The encryption algorithm is a 128-bit cipher called E0.
Security mode 1 and 2 are implemented to keep the same or similar behavior as for previous versions
of u-blox Bluetooth products.
Secure Simple Pairing (SSP) was introduced in Bluetooth 2.1 to improve security and simplify the
pairing process. SSP uses a form of public key cryptography and the just works, numeric comparison,
passkey entry, and out of band authentication mechanisms.
•
Just works: No user interaction is needed, except that the user may need to confirm the pairing
process. The method is typically used by devices with very limited IO capabilities.
•
Numeric comparison: A 6-digit numeric code is displayed on each device where the user compares
the numbers to ensure they are identical.
•
Passkey entry: Either a 6-digit numeric code is displayed on one device that the user enters on the
other device, or the same 6-digit numbers are entered on both devices.
•
Out of band: This security mode is used to connect to a remote device when the temporary key
has been exchanged out of band.
Use the security mode 1 (Bluetooth 2.1 auto accept security)
AT+UBTSM=1
to start with. It is highly
recommended to analyze the security and if appropriate, use a more secured solution, for example
security mode 2 (Bluetooth 2.1 Just Works)
AT+UBTSM=2
.
2.9
Low power modes
The Standby mode is one of the power saving modes in the NINA-B31 module that essentially powers
down the module but keeps the system RAM and allows incoming connection to the module. The
Sleep mode is the deepest power saving mode of NINA-B31 modules, and does not allow any
connection to wake up the module. The low power modes in NINA-B31 are set using the AT&D
command.
2.9.1
Standby mode
The standby mode in NINA-B31, enabled with
AT&D3
, is used to disable the UART. The radio is still
active and the UART can be activated again either on a logical 0 to logical 1 signal transition on the
DTR line, or by an incoming Bluetooth connection establishment.
For more information about Standby mode, see NINA-B3 series Data Sheet [2].
2.9.2
Sleep mode
The sleep mode in the NINA-B31 module is enabled with the command
AT&D4
, which causes a logical
0 to logical 1 signal transition of the DTR line to completely shut off the module. Upon a logical 1 to
logical 0 signal transition on the DTR line, the module is started again. This is the lowest power mode,
and NINA-B31 cannot keep or make any connection in this mode.
For more information about Sleep mode, see the NINA-B3 series Data Sheet [2].
