Bluetooth Low Energy protocol stack

S140 SoftDevice Specification

The Bluetooth® 5.1 compliant Host and Controller implemented by the SoftDevice are fully qualified with multirole support (Central, Observer, Peripheral, and Broadcaster).

The SoftDevice allows applications to implement standard Bluetooth Low Energy profiles as well as proprietary use case implementations. The Application Programming Interface (API) is defined above the Generic Attribute Protocol (GATT), Generic Access Profile (GAP), and Logical Link Control and Adaptation Protocol (L2CAP). Other protocols, such as the Attribute Protocol (ATT), Security Manager (SM), and Link Layer (LL), are managed by the higher layers of the SoftDevice as shown in the following figure.

The nRF5 Software Development Kit (nRF5 SDK) complements the SoftDevice with Service and Profile implementations. Single-mode System on Chip (SoC) applications are enabled by the Bluetooth Low Energy protocol stack and nRF52 Series SoC.

Figure 1. SoftDevice stack architecture
Page-1 Box.24 nRF5x SoC nRF5x SoC Box.13 SoftDevice SoftDevice Box.22 Host Host Box.23 Controller Controller Box.38 Physical Layer (PHY) Physical Layer (PHY) Box.40 Generic Attribute Profile (GATT) Generic Attribute Profile (GATT) Box.41 Attribute Protocol (ATT) Attribute Protocol (ATT) Box.43 Logical Link Control and Adaptation Layer Protocol (L2CAP) Logical Link Control and Adaptation Layer Protocol (L2CAP) Box.52 Link Layer (LL) Link Layer (LL) Double flexi-arrow.8 Double flexi-arrow.12 Box.4 Security Manager (SM) Security Manager (SM) Sheet.18 Generic Access Profile (GAP) Generic Access Profile (GAP) Box.25 Application Profiles and Services Application Profiles and Services Double flexi-arrow.7
  • Profile and service support
    This section lists the profiles and services adopted by the Bluetooth Special Interest Group at the time of publication of this document.
  • Bluetooth Low Energy features
    The Bluetooth Low Energy protocol stack in the SoftDevice has been designed to provide an abstract but flexible interface for application development for Bluetooth Low Energy devices.
  • Limitations on procedure concurrency
    When the SoftDevice has established multiple connections as a Central, the concurrency of protocol procedures will have some limitations.
  • Bluetooth Low Energy role configuration
    The S140 SoftDevice stack supports concurrent operation in multiple Bluetooth Low Energy roles. The roles available can be configured when the S140 SoftDevice stack is enabled at runtime.