10. Peripheral only mode
The Proteus-III implements a new feature that allows the easy integration of the Proteus-III
Bluetooth
®
LE module to an already existing host. The peripheral only mode offers a plug
and play installation without previous configuration of the Proteus-III. It is tailored for easy
communication with mobile Bluetooth
®
LE devices like smart phones.
The peripheral only mode is a special operation mode, that uses the user settings and the
peripheral functions of the normal mode described in the previous chapters. It has to be
enabled during the module start-up and contains the following key features:
• Peripheral only functions: The Proteus-III only contains the functions of a peripheral
device. Thus, it is advertising until another Bluetooth
®
LE enabled device connects
to it. In this case, the UART of the Proteus-III is enabled, the
pin shows that
the channel is open and bidirectional data transmission can start. As soon as the
connection is closed, the UART is disabled again to save power. Since all central
functions are no longer valid, the module cannot initiate any connection or run scans.
• Transparent UART interface: The serial interface of the Proteus-III is no longer driven
by commands. This means, when the UART of the module is enabled (i.e. only when a
channel is open, indicated by both LEDs active), data sent to the UART is transmitted
by the Proteus-III to the connected Bluetooth
®
LE enabled device. On the other hand,
all data received by radio is send from the Proteus-III to the connected host without
additional header Bytes. The UART is only running, when a channel is open. Thus,
power is saved during the advertising period. Depending on the configured connection
interval, only one packet per interval is allowed to be transmitted. Since the commands
of the command interface are no longer valid, a Proteus-III cannot be configured when
running in peripheral only mode.
• Pairing: The default security mode is the static passkey pairing method (see
), with the default key "123123". The bonding feature is enabled
by default.
10.1. Reasons to use the peripheral only mode
The Proteus-III peripheral only mode equips custom applications with a Bluetooth
®
LE inter-
face (to be accessible by other Bluetooth
®
LE devices) without installation effort.
To setup a connection to the Proteus-III in peripheral only mode the central device has to
insert the Proteus-III’s static passkey. As soon as the channel to a connected Bluetooth
®
LE
central device is open, the
pin switches on to signalize that data can be exchanged
now. When the connection was shut down by the Bluetooth
®
LE central device, the
pin switches off again.
Due to the transparent UART interface, data can be exchanged without additional headers.
Furthermore, the peripheral only mode allows an energy efficient operation of the Bluetooth
®
LE
interface, since the UART is only enabled when it is really used.
10.2. Restrictions
In peripheral only mode, it is not possible to use the security modes "Lesc pass key" and
"Lesc numeric comparison", as these security features require to output the LESC key on
the UART.
Proteus-III reference manual version 1.3
© August 2020
www.we-online.com/wireless-connectivity
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