BLE role configuration

The S132 SoftDevice stack supports concurrent operation in multiple Bluetooth® low energy roles. The roles available can be configured when the S132 SoftDevice stack is enabled at runtime.

The SoftDevice provides a mechanism for enabling the number of central or peripheral roles the application can run concurrently. The SoftDevice can be configured with multiple connections as a Central or Peripheral. The SoftDevice supports running one Advertiser or Broadcaster and one Scanner or Observer concurrently with the BLE connections.

An Initiator or a connectable Advertiser can only be started if the number of connections is less than the maximum supported.

When the SoftDevice is enabled, it will allocate memory for the connections the application has requested. The size of the memory pool for a connection is determined by the ATT MTU and the event length (duration) of the connection. The SoftDevice will make sure that it has enough buffers to avoid buffer starvation within a connection event.

The SoftDevice supports per connection bandwidth configuration by giving the application control over the connection interval and the length of the connection event. By default, connections are set to have an event length of 3.75 ms. This is sufficient for three packet pairs in a connection event with the default 27 octet-long Link Layer payload for Data Channel PDUs.

In addition to the bandwidth feature, connection bandwidth can be increased by enabling Connection Event Length Extension. See Connection timing with Connection Event Length Extension for more information. Enabling Connection Event Length Extension does not increase the size of the SoftDevice memory pools.

Bandwidth and multilink scheduling can affect each other. See Scheduling for details. Knowledge about multilink scheduling can be used to get predictable performance on all links. Refer to Suggested intervals and windows for details about recommended configurations.

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