Selecting Suitable Connection Parameters for Apple Devices#

Introduction#

For each Bluetooth connection, a set of parameters can be changed dynamically, depending on the application requirements. These parameters include connection interval, peripheral latency, and supervision timeout. For example, to minimize power consumption, you can increase the connection interval and peripheral latency. This reduces the RF duty cycle and allows the peripheral to remain in sleep mode longer when there is no need to transmit user data.

For more details about Bluetooth connections, see Bluetooth LE Fundamentals.

The central device (typically a mobile device) controls which connection parameters are used. When the central device initiates a connection to a peripheral, it selects the default connection parameters. The peripheral can request an update to the connection parameters. However, the central can either accept or reject the request.

Depending on the central device, different restrictions can apply to the parameter combinations that are accepted. This document focuses on Apple's recommendations for iOS devices.

Apple Bluetooth Device Guidelines#

The rules for selecting connection parameters for BLE peripherals are defined in the Accessory Design Guidelines for Apple Devices, which are available for download here.

BLE connection parameters are discussed in section 49.6 Connection Parameters. For example, the minimum connection interval is specified as 15 ms. Note that the minimum connection interval allowed by the Bluetooth Core Specification is 7.5 ms

At the time of writing, the latest version of the guideline document was R21 (dated 2023-10-12).