Hardware Reference
In-Depth Information
The Specification
In June 2010, the Bluetooth SIG introduced Bluetooth Low Energy with version 4.0 of
the Bluetooth Core Specfication. The specification had been several years in the making
and most of the controversial sections and decisions were finally ironed out by the
companies involved in the development process, with a few additional concerns left to
be dealt with in subsequent updates of the specification.
The first such major update, Bluetooth 4.1, was released in December 2013 and is the
current reference for anyone looking to develop BLE products. Althought the basic
building blocks, procedures, and concepts remained intact, this release also introduced
multiple changes and improvements to smooth the experience of the user.
As with all Bluetooth specifications, 4.1 is backwards compatible with 4.0, ensuring the
correct interoperability among devices implementing different specification versions.
The specifications allow developers to release and qualify products against either of the
versions (until deprecated), although the rapid adoption of new specification releases
and the fact that the 4.1 version standardizes several common practices among devices
makes it recommendable to target the latest available one.
Unless otherwise noted, this topic uses the Bluetooth 4.1 specification as reference.
Wherever necessary, and especially when mentioning a noteworthy change or addition,
we will clarify when the previous 4.0 specification does not cover a particular area.
To obtain the latest adopted version of the Bluetooth specification, see the Bluetooth
Configurations
The Bluetooth specification covers both classic Bluetooth (the well-known wireless
standard that has been commonplace in many consumer devices for a number of years
now) and Bluetooth Low Energy (the new, highly optimized wireless standard intro‐
duced in 4.0). Those two wireless communication standards are
not directly compati‐
ble
and Bluetooth devices qualified on any specification version prior to 4.0 cannot
communicate in any way with a BLE device. The on-air protocol, the upper protocol
layers, and the applications are different and incompatible between the two technolo‐
gies.
Based on Specification Support
Table 1-1
shows the wireless technologies implemented for the three main device types
on the market today.
