Distribution
require a higher radio duty cycle and consume more power. Some applications and data can use this advertisement mode to save power and do not require a bidirectional full duplex RF link. One example is a temperature sensor where temperature can be broadcasted periodically.
In advertisement mode only 3 channels
are used to broadcast the data. The 3 channels are dedicated for advertising, scanning and connecting of Bluetooth Smart device. There are 37 other channels than can then be used for connection oriented data channels. This is a total of 40 channels with 2MHz spacing. Bluetooth Classic uses 80 channels with 1MHz spacing. The 3 advertising channels are strategically placed at 2402 MHz, 2426 MHz and 2480 MHz to avoid the 3 non- overlapping WiFi channels of channel 1, channel 6 and channel 11. In an active connection there are still 9 channels that do not overlap with these WiFi channels. The 3 advertisement channels are also used to discover and create active connections between devices. After discovery and connection requests, the devices then start a frequency hopping spread spectrum (FHSS) scheme on the other 37 channels.
contains a number of attributes, and the GATT Profile defines how to use the ATT Protocol to discover, read, write and obtain data. The services are used as defined in the profile specifications and GATT enables you to expose these services and characteristics within the profiles specified. Currently there are 18 GATT based
profiles with defined Attributes that are reserved. These Attributes have universally unique identifiers (UUID). There are 16-bit, 32-bit and 128-bit UUIDs that can be used. An 128-bit UUID can be used for proprietary use for custom profiles and applications for vendor specific data. There is the lack of a Serial Port Profile (SPP) in Bluetooth Smart. Applications using SPP are basically proprietary data transfers. Custom GATT profiles are essentially the same concept of proprietary data transfers and can be used for the SPP-like implementation.
In December of 2013, the Bluetooth Special Interest Group ratified the 4.1 Core specification that added optional features to Bluetooth Smart. Revision 4.1 extends functionality that is already provided in revision 4.0 of the specification. All of the new 4.1 functions are optional and it does not change or add mandatory items to revision 4.0. This means 4.1 and 4.0
such as moving out of range; the availability of dedicated L2CAP oriented channels and dual Mode Topology and
The DoC and Listing is followed by a fee for the process. The fee ranges from $2K to $8K per EPL depending on the status of the Lister with the Bluetooth SIG,
Associate Member or Adopter, size and revenue of the Lister. The fees are not associated with Future Electronics or partners. This charge is directly
Figure 3: Proximity Profile example with GATT
Link Layer Topology Software features that allow a Bluetooth Smart device to become both a Central and Peripheral device simultaneously.
Bluetooth qualification listing In February of this year an additional means of funding the Bluetooth SIG’s activities was
Figure 2: Bluetooth Smart Channel map with WiFi
Previously, Bluetooth Smart was mentioned as a “wire replacement” technology. However, the information is exchanged using a Client-Server model. It uses a service-based architecture based on the ATTribute protocol (ATT). All communication in Bluetooth Smart takes place over the Generic ATTribute profile (GATT). An application or another profile uses the GATT profile so a client and server can interact in a structured way. The server
devices are compatible. Previously qualified Bluetooth Smart 4.0 solutions do not need to re-qualify, but for 4.1 certification, the solutions will have to retest again. Revision 4.1 changes included: added coexistence signalling between Bluetooth Smart and Cellular technologies such as LTE; improved Link Supervision Timeout handling; the Link Manager between devices can now negotiate reconnection intervals in the case of a connection loss
implemented to meet the demands placed on the alliance with the growth in Bluetooth products coming to the market. These changes don’t alter any qualification process, and Bluetooth interoperability testing still continues to support designs past and present. The change addresses the mechanism by which products are qualified and listed. Historically, customers were allowed to reference prequalified components and subsystems for such modules and list their products at no charge. Now, members implementing Bluetooth wireless technology into a product must complete a Declaration of Compliance (DoC) and a Listing for the Qualified Design they built, changed, used or branded. A Listing may include multiple products if each product implements the same Qualified Design referenced in the DoC. If a customer creates an OEM product that may be rebranded as another company or several other companies, then they too need to list the product themselves. An End Product Listing (EPL) can only be created by a Bluetooth SIG member, and an EPL cannot be created by one member on behalf of another company.
implemented by the Bluetooth SIG and is separate from the certification and testing costs.
Solutions Future Connectivity Solutions (FCS) is able to supply systems on Chip (SoC) and module solutions. These solutions are provided with ready-to-go Bluetooth Smart Protocol stacks that are pre-certified with easy profile and application development environments. Sizes are as small as 2.5mm
Figure 4: Custom Profile using GATT and custom UUIDs
x 2.5mm SoC to 5mm x 5mm fully certified modules. Solutions with 4mA peak with >600nA sleep modes are also available. Modules and SoCs with integrated slow clocks, buck/boost, BALUN, antenna, with Bluetooth and FCC, IC, CE certification are available. Roadmap products will integrate more features such as cap-touch IO, integrated accelerometer and MEMS sensors, M0+ apps processors and energy harvesting capabilities. Each solution will have a best fit in different types of Bluetooth Smart Devices.
Future Electronics |
www.futureelectronics.com
Allen Cabreros is Regional Wireless Specialist, Future Connectivity Solutions (a division of Future Electronics)
www.cieonline.co.uk
Components in Electronics
September 2014 17
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