Hardware Reference
In-Depth Information
Figure 1-2 shows the various hardware configurations with the layers of the Bluetooth
protocol stack.
Figure 1-2. Hardware configurations
Simple sensors tend to use SoC configurations to keep the cost and printed circuit board
(PCB) complexity low, whereas smartphones and tablets usually opt for the Dual IC
over HCI configuration because they usually already have a powerful CPU available to
run the protocol stack. The Dual IC with connectivity device configuration is used in
other scenarios, one of which could be a watch with a specialized microcontroller to
which BLE connectivity is added without overhauling the whole design.
Key Limitations
Like all things in engineering, good design is all about making the right tradeoffs, and
Bluetooth Low Energy is no different. BLE doesn't attempt to be a solution to every
wireless data transfer need, and classic Bluetooth, WiFi, NFC, and other wireless tech‐
nologies clearly still have their place, with their own unique set of design tradeoffs and
decisions.
To help understand what BLE is (and isn't), it's useful to recognize its key limitations
(as defined in the Bluetooth 4.0 specification and later) and how these limitations trans‐
late into real-world products.
Data Throughput
The modulation rate of the Bluetooth Low Energy radio is set by the specification at a
constant 1Mbps. This sets the theoretical upper limit for the throughput that BLE can
provide, but in actual terms, this limit is typically lowered significally by a variety of
 
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