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Bluetooth Low Energy

Bluetooth Low Energy (BLE) is the energy-efficient variant of the well-known radio standard Bluetooth. BLE was developed specifically for the Internet of Things (IoT) and was introduced with Bluetooth 4.2.

The low energy consumption makes BLE to an optimal radio standard for devices that have to deal with a very small energy supply over a long period of time. The data transmission can also take place without connection - BLE can therefore be used wherever a wireless, energy-saving and uncomplicated data exchange is needed.
NetModule integrates BLE into its devices and thus opens up further possibilities of robust mobile communication.

Technology

BLE operates on the 2.4 GHz ISM band and has a range of approximately 10-20 meters depending on the environment.
A BLE device communicates either connectionless or connection oriented with other BLE devices. Essentially, BLE uses two profiles for data transfer: GAP (Generic Access Profile) and GATT (Generic Attribute Profile).

GAP
GAP manages the so-called advertising and the connection setup between devices. GAP is therefore there to make a device visible to others and to control how devices can interact with each other.

GAP defines two roles that devices can take on:

  • Peripheral (sender)
    Usually small devices as sensors, which send their data to powerful devices.
  • Central (reveicer)
    They scan their environment for advertisements to process them afterwards.

A peripheral can be noticeable in a certain time interval by sending out its advertising data. This may be an ID or something similar. A central device can respond and request additional information. 

If a peripheral transmits its data, centrals can listen and process the data on request. This creates the so-called broadcasting topology.
A central device can send connection requests to multiple peripherals. If two devices are connected, no more advertisements are sent by the peripheral and it remains hidden for all other centrals and GATT comes into operation.

GATT

After the connection has been established, data is exchanged in both directions using GATT. During the so-called connection interval which was negotiated during the connection setup, the central asks the peripheral again and again whether new data is available.

Use Cases

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