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Bluetooth: Coordinated Set Identification Profile

This document describes how to run the coordinated set identification functionality, both as a client and as a server. Note that in the examples below, some lines of debug have been removed to make this shorter and provide a better overview.

Set Coordinator (Client)

The client will typically be a resource-rich device, such as a smartphone or a laptop. The client is able to lock and release members of a coordinated set. While the coordinated set is locked, no other clients may lock the set.

To lock a set, the client must connect to each of the set members it wants to lock. This implementation will always try to connect to all the members of the set, and at the same time. Thus if the set size is 3, then BT_MAX_CONN shall be at least 3.

If the locks on set members shall persists through disconnects, it is necessary to bond with the set members. If you need to bond with multiple set members, make sure that BT_MAX_PAIRED is correctly configured.

Using the Set Coordinator

When the Bluetooth stack has been initialized (bt init), and a set member device has been connected, the call control client can be initialized by calling csip_set_coordinator init, which will start a discovery for the TBS uuids and store the handles, and optionally subscribe to all notifications (default is to subscribe to all).

Once the client has connected and discovered the handles, then it can read the set information, which is needed to identify other set members. The client can then scan for and connect to the remaining set members, and once all the members has been connected to, it can lock and release the set.

It is necessary to enable CONFIG_BT_CSIP_SET_COORDINATOR_LOG_LEVEL_DBG to properly use the set coordinator.

csip_set_coordinator --help
csip_set_coordinator - Bluetooth CSIP_SET_COORDINATOR shell commands
Subcommands:
   init              :Initialize CSIP_SET_COORDINATOR
   discover          :Run discover for CSIS on peer device [member_index]
   discover_members  :Scan for set members <set_pointer>
   lock_set          :Lock set
   release_set       :Release set
   lock              :Lock specific member [member_index]
   release           :Release specific member [member_index]
   lock_get          :Get the lock value of the specific member and instance
                     [member_index [inst_idx]]

Example usage

Setup

uart:~$ init
uart:~$ bt connect xx:xx:xx:xx:xx:xx public

When connected

Discovering sets on a device:

uart:~$ csip_set_coordinator init
<dbg> bt_csip_set_coordinator.primary_discover_func: [ATTRIBUTE] handle 0x0048
<dbg> bt_csip_set_coordinator.primary_discover_func: Discover complete, found 1 instances
<dbg> bt_csip_set_coordinator.discover_func: Setup complete for 1 / 1
Found 1 sets on device
uart:~$ csip_set_coordinator discover_sets
<dbg> bt_csip_set_coordinator.SIRK
36 04 9a dc 66 3a a1 a1 |6...f:..
1d 9a 2f 41 01 73 3e 01 |../A.s>.
<dbg> bt_csip_set_coordinator.csip_set_coordinator_discover_sets_read_set_size_cb: 2
<dbg> bt_csip_set_coordinator.csip_set_coordinator_discover_sets_read_set_lock_cb: 1
<dbg> bt_csip_set_coordinator.csip_set_coordinator_discover_sets_read_rank_cb: 1
Set size 2 (pointer: 0x566fdfe8)

Discover set members, based on the set pointer above:

uart:~$ csip_set_coordinator discover_members 0x566fdfe8
<dbg> bt_csip_set_coordinator.csip_found: Found CSIS advertiser with address 34:02:86:03:86:c0 (public)
<dbg> bt_csip_set_coordinator.is_set_member: hash: 0x33ccb1, prand 0x5bfe6a
<dbg> bt_csip_set_coordinator.is_discovered: 34:02:86:03:86:c0 (public)
<dbg> bt_csip_set_coordinator.is_discovered: 34:13:e8:b3:7f:9e (public)
<dbg> bt_csip_set_coordinator.csip_found: Found member (2 / 2)
Discovered 2/2 set members

Lock set members:

uart:~$ csip_set_coordinator lock_set
<dbg> bt_csip_set_coordinator.bt_csip_set_coordinator_lock_set: Connecting to 34:02:86:03:86:c0 (public)
<dbg> bt_csip_set_coordinator.csip_set_coordinator_connected: Connected to 34:02:86:03:86:c0 (public)
<dbg> bt_csip_set_coordinator.discover_func: Setup complete for 1 / 1
<dbg> bt_csip_set_coordinator.csip_set_coordinator_lock_set_init_cb:
<dbg> bt_csip_set_coordinator.SIRK
36 04 9a dc 66 3a a1 a1 |6...f:..
1d 9a 2f 41 01 73 3e 01 |../A.s>.
<dbg> bt_csip_set_coordinator.csip_set_coordinator_discover_sets_read_set_size_cb: 2
<dbg> bt_csip_set_coordinator.csip_set_coordinator_discover_sets_read_set_lock_cb: 1
<dbg> bt_csip_set_coordinator.csip_set_coordinator_discover_sets_read_rank_cb: 2
<dbg> bt_csip_set_coordinator.csip_set_coordinator_write_lowest_rank: Locking member with rank 1
<dbg> bt_csip_set_coordinator.notify_func: Instance 0 lock was locked
<dbg> bt_csip_set_coordinator.csip_set_coordinator_write_lowest_rank: Locking member with rank 2
<dbg> bt_csip_set_coordinator.notify_func: Instance 0 lock was locked
Set locked

Release set members:

uart:~$ csip_set_coordinator release_set
<dbg> bt_csip_set_coordinator.csip_set_coordinator_release_highest_rank: Releasing member with rank 2
<dbg> bt_csip_set_coordinator.notify_func: Instance 0 lock was released
<dbg> bt_csip_set_coordinator.csip_set_coordinator_release_highest_rank: Releasing member with rank 1
<dbg> bt_csip_set_coordinator.notify_func: Instance 0 lock was released
Set released

Coordinated Set Member (Server)

The server on devices that are part of a set, consisting of at least two devices, e.g. a pair of earbuds.

Using the Set Member

csip_set_member --help
csip_set_member - Bluetooth CSIP set member shell commands
Subcommands:
   register      :Initialize the service and register callbacks [size <int>]
                  [rank <int>] [not-lockable] [sirk <data>]
   lock          :Lock the set
   release       :Release the set [force]
   sirk          :Set the currently used SIRK <sirk>
   get_sirk      :Get the currently used SIRK
   sirk_rsp      :Set the response used in SIRK requests <accept, accept_enc,
                  reject, oob>

Example Usage

Setup

uart:~$ bt init
uart:~$ csip_set_member register

Setting a new SIRK

This command can modify the currently used SIRK. To get the new RSI to advertise on air, bt adv-data or bt advertise must be called again to set the new advertising data. If CONFIG_BT_CSIP_SET_MEMBER_NOTIFIABLE is enabled, this will also notify connected clients.

uart:~$ csip_set_member sirk 00112233445566778899aabbccddeeff
SIRK updated

Getting the current SIRK

This command can get the currently used SIRK.

uart:~$ csip_set_member get_sirk
SIRK
36 04 9a dc 66 3a a1 a1 |6...f:..
1d 9a 2f 41 01 73 3e 01 |../A.s>.