Integration with applications

The SoftDevice Controller is an RTOS-agnostic library built for the Nordic Semiconductor nRF52 and nRF53 Series that supports Bluetooth 5.

For the nRF53 Series, the requirements described in this document are only relevant for applications running alongside the SoftDevice Controller on the network processor.

Applications utilizing the SoftDevice Controller library are responsible for the following:

  • Ensuring a source of random numbers is available to the SoftDevice Controller (see the message sequence charts below).

  • The SoftDevice Controller relies on the functionality provided by Nordic Semiconductor’s Multiprotocol Service Layer, which has its own set of requirements that the application must follow.

  • Ensuring thread-safe operation. This can be achieved by either:

    • Calling all SoftDevice Controller and MPSL APIs from the same execution priority.

    • Ensuring that no API call is interrupted by other API calls, for example by using critical sections.

  • Configuring the number of available links:

    • Link configuration must be done before enabling the controller.

    • The application is required to provide a memory buffer the size of which is dependent on the link configuration.

The following peripherals are owned by the SoftDevice Controller and must not be accessed directly by the application:

  • ECB

  • AAR

  • NVMC

  • PPI channels from 17 to 31 (for the nRF52 Series)

  • DPPI channels from 0 to 13 (for the nRF53 Series)

Some of these peripherals can be accessed by APIs provided in sdc_soc.h and by Multiprotocol Service Layer. The application can access most of these directly using Timeslot.

Message sequence charts

The following message sequence chart shows an example of how to initialize the library. The Multiprotocol Service Layer must be initialized before the SoftDevice Controller is initialized. The application can choose the features that are enabled and the number of links that are supported.

msc {
hscale = "1.5";
Host,Controller;
|||;
Host rbox Controller [label = "Library initialization"];
Host->Controller      [label="sdc_init()"];
Host rbox Controller [label = "Library configuration"];
Host->Controller      [label="sdc_rand_source_register(...)"];
Host->Controller      [label="sdc_cfg_set(SDC_CFG_TYPE_ADV_COUNT)"];
Host->Controller      [label="sdc_cfg_set(SDC_CFG_TYPE_CENTRAL_COUNT)"];
Host->Controller      [label="sdc_cfg_set(SDC_CFG_TYPE_PERIPHERAL_COUNT)"];
Host rbox Controller[label = "Feature inclusion"];
Host->Controller      [label="sdc_support_adv()"];
Host->Controller      [label="sdc_support_peripheral()"];
Host->Controller      [label="sdc_support_2m_phy()"];
Host rbox Controller [label = "Enable the SoftDevice Controller"];
Host->Controller      [label="sdc_enable()"];
}

The following message sequence chart shows a scenario where the application sends a command to the controller. Later, it retrieves an event and a data packet. When the host signal is triggered, this indicates that one or more HCI data or event packets are available. Therefore, the host should try to pull data and events until it fails.

msc {
hscale = "1.5";
Host,Controller;
|||;
Host rbox Controller [label = "Send a command to the controller"];
Host->Controller      [label="sdc_hci_cmd_put()"];
Host<-Controller      [label="Host signal is triggered"];
Host->Controller      [label="sdc_evt_get()"];
Host<<Controller      [label="Command Complete event"];
Host rbox Controller [label = "Send data to the controller"];
Host->Controller      [label="sdc_hci_data_put()"];
Host<-Controller      [label="Host signal is triggered"];
Host->Controller      [label="sdc_evt_get()"];
Host<<Controller      [label="HCI Number Of Completed packets"];
Host rbox Controller [label = "The controller receives some data and raises an event"];
Host<-Controller      [label="Host signal is triggered"];
Host->Controller      [label="sdc_evt_get()"];
Host<<Controller      [label="Retrieved event"];
Host->Controller      [label="sdc_data_get()"];
Host<<Controller      [label="Retrieved data"];
}

Architecture diagrams

The image below shows how the SoftDevice Controller and MPSL integrates into an RTOS-free environment.

../../_images/Architecture_Without_RTOS1.svg

The image below shows how the SoftDevice Controller and MPSL integrates into an RTOS.

../../_images/Architecture_With_RTOS1.svg