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are “Hey AMB2621!”. The associated Received Signal Strength Indication (RSSI)
value is 0xC8, i.e. -56 dBm.)
If now the AMB2621 is to transmit data such as “Hey App!” to the smartphone, the
host connected has to send the following data to AMB2621 via UART:
that these data are transmitted to the
smartphone connected.
BLE possibilities fully
exploited
With the Peripheral Only mode, Amber
wireless uses a typical function in
mobile communications applications
for industrial purposes. In another
place, the manufacturer purposefully
moves away from the common
standards. For wireless, AMB2621
offers the “AMBER-SPP-like” profile,
which allows transmission of general
data between the two connection
partners. The Bluetooth Serial Port
Profile (SPP) does not actually exist
anymore for BLE, which is why AMBER
wireless offers its own solution here.
Here the optional Bluetooth 4.2 feature
“data length extension” (DLE) is used,
such that payload sizes up to 243 bytes
per Bluetooth packet are possible with
the AMB2621. This raises throughput
up to 5 kB/s. Familiar pairing methods
like JustWorks or StaticPasskey are
made available in order to ensure
stable data transmission. In the case
of StaticPasskey, a 6-digit key has
to be entered on a terminal device
such that a secure connection can be
established. The bonding function,
i.e. the use of keys already used
for re-authentication, is available in
AMB2621.
Further application options
In many cases, the decision between
command control of the chip and the
Peripheral mode is clearly prescribed
by the requirements of the application.
However, it is also possible to provide
the otherwise firmly soldered pins
with a switch for mode selection. This
can be useful if the wireless module
is normally used for the data request
initiated by the mobile device, but is
occasionally opened by the device for
more complex communication tasks,
such as maintenance or configuration
tasks.
The module is also capable of all
other Bluetooth modes. Broadcasting
for example: In place of connection-
oriented data transmission, so-called
beacons are used to emit power-
saving data – the module “sleeps”
when it does not transmit. This
function is well-suited for battery-
operated sensor applications like the
periodic transmission of temperature
or other environmental data. Distance
estimation of a transmitter by
means of the RSSI value or position
determination by triangulation of
several beacons is also conceivable.
Conclusion
Instead of equipping a device with
a display, making a smartphone
fit for use as a user interface or
developing a door control system with
a mobile device – these are typical
applications that should ideally be run
independently of WLAN availability –
here Bluetooth is a viable alternative.
The wireless module introduced here
makes integration especially easy.
By the way, samples of AMB2621
and the associated evaluation board
AMB2621-EV are available from stock.
Field sales engineers are available on-
site to provide support in the design-
in process and also to elaborate
specifications if customer-specific
adaptation of the AMBER firmware
stack is required.
AMBER wireless AMB2621
FCC and CE certified BLE module
Just 8x11x1.8 mm in size
Nordic Semiconductor nRF52832
BLE chip
32 bit ARM Cortex-M4 CPU, 512 kB
Flash memory
Amber SPP-over-BLE profile
Low power consumption (TX
5.3mA@0dBm, RX 5.4mA, sleep
0.4µA)
Ideal for expanding battery-operated
systems with a BLE interface
AMB2621 is a 2.4-GHz-BLE wireless
module compliant with the
Bluetooth-Smart-4.2 standard.
New-Tech Magazine Europe l 47