The Bluetooth Shell is an application based on the Shell module. It offer a collection of commands made to easily interact with the Bluetooth stack.
Bluetooth Shell Setup and Usage
When it’s done, connect to the CLI using your favorite serial terminal application. You should see the following prompt:
For more details on general usage of the shell, see Shell.
The first step is enabling Bluetooth. To do so, use the
bt init command. The following
message is printed to confirm Bluetooth has been initialized.
uart:~$ bt init Bluetooth initialized Settings Loaded [00:02:26.771,148] <inf> fs_nvs: nvs_mount: 8 Sectors of 4096 bytes [00:02:26.771,148] <inf> fs_nvs: nvs_mount: alloc wra: 0, fe8 [00:02:26.771,179] <inf> fs_nvs: nvs_mount: data wra: 0, 0 [00:02:26.777,984] <inf> bt_hci_core: hci_vs_init: HW Platform: Nordic Semiconductor (0x0002) [00:02:26.778,015] <inf> bt_hci_core: hci_vs_init: HW Variant: nRF52x (0x0002) [00:02:26.778,045] <inf> bt_hci_core: hci_vs_init: Firmware: Standard Bluetooth controller (0x00) Version 3.2 Build 99 [00:02:26.778,656] <inf> bt_hci_core: bt_init: No ID address. App must call settings_load() [00:02:26.794,738] <inf> bt_hci_core: bt_dev_show_info: Identity: EB:BF:36:26:42:09 (random) [00:02:26.794,769] <inf> bt_hci_core: bt_dev_show_info: HCI: version 5.3 (0x0c) revision 0x0000, manufacturer 0x05f1 [00:02:26.794,799] <inf> bt_hci_core: bt_dev_show_info: LMP: version 5.3 (0x0c) subver 0xffff
Identities are a Zephyr host concept, allowing a single physical device to behave like multiple logical Bluetooth devices.
The shell allows the creation of multiple identities, to a maximum that is set by the Kconfig symbol
CONFIG_BT_ID_MAX. To create a new identity, use
bt id-create command. You
can then use it by selecting it with its ID
bt id-select <id>. Finally, you can list all the
available identities with
Scan for devices
Start scanning by using the
bt scan on command. Depending on the environment you’re in, you
may see a lot of lines printed on the shell. To stop the scan, run
bt scan off, the
scrolling should stop.
Here is an example of what you can expect:
uart:~$ bt scan on Bluetooth active scan enabled [DEVICE]: CB:01:1A:2D:6E:AE (random), AD evt type 0, RSSI -78 C:1 S:1 D:0 SR:0 E:0 Prim: LE 1M, Secn: No packets, Interval: 0x0000 (0 us), SID: 0xff [DEVICE]: 20:C2:EE:59:85:5B (random), AD evt type 3, RSSI -62 C:0 S:0 D:0 SR:0 E:0 Prim: LE 1M, Secn: No packets, Interval: 0x0000 (0 us), SID: 0xff [DEVICE]: E3:72:76:87:2F:E8 (random), AD evt type 3, RSSI -74 C:0 S:0 D:0 SR:0 E:0 Prim: LE 1M, Secn: No packets, Interval: 0x0000 (0 us), SID: 0xff [DEVICE]: 1E:19:25:8A:CB:84 (random), AD evt type 3, RSSI -67 C:0 S:0 D:0 SR:0 E:0 Prim: LE 1M, Secn: No packets, Interval: 0x0000 (0 us), SID: 0xff [DEVICE]: 26:42:F3:D5:A0:86 (random), AD evt type 3, RSSI -73 C:0 S:0 D:0 SR:0 E:0 Prim: LE 1M, Secn: No packets, Interval: 0x0000 (0 us), SID: 0xff [DEVICE]: 0C:61:D1:B9:5D:9E (random), AD evt type 3, RSSI -87 C:0 S:0 D:0 SR:0 E:0 Prim: LE 1M, Secn: No packets, Interval: 0x0000 (0 us), SID: 0xff [DEVICE]: 20:C2:EE:59:85:5B (random), AD evt type 3, RSSI -66 C:0 S:0 D:0 SR:0 E:0 Prim: LE 1M, Secn: No packets, Interval: 0x0000 (0 us), SID: 0xff [DEVICE]: 25:3F:7A:EE:0F:55 (random), AD evt type 3, RSSI -83 C:0 S:0 D:0 SR:0 E:0 Prim: LE 1M, Secn: No packets, Interval: 0x0000 (0 us), SID: 0xff uart:~$ bt scan off Scan successfully stopped
As you can see, this can lead to a high number of results. To reduce that number and easily find a
specific device, you can enable scan filters. There are four types of filters: by name, by RSSI, by
address and by periodic advertising interval. To apply a filter, use the
command followed by the type of filters. You can add multiple filters by using the commands again.
For example, if you want to look only for devices with the name test shell:
uart:~$ bt scan-filter-set name "test shell"
Or if you want to look for devices at a very close range:
uart:~$ bt scan-filter-set rssi -40 RSSI cutoff set at -40 dB
Finally, if you want to remove all filters:
uart:~$ bt scan-filter-clear all
You can use the command
bt scan on to create an active scanner, meaning that the scanner
will ask the advertisers for more information by sending a scan request packet. Alternatively, you
can create a passive scanner by using the
bt scan passive command, so the scanner will not
ask the advertiser for more information.
Connecting to a device
To connect to a device, you need to know its address and type of address and use the
bt connect command with the address and the type as arguments.
Here is an example:
uart:~$ bt connect 52:84:F6:BD:CE:48 random Connection pending Connected: 52:84:F6:BD:CE:48 (random) Remote LMP version 5.3 (0x0c) subversion 0xffff manufacturer 0x05f1 LE Features: 0x000000000001412f LE PHY updated: TX PHY LE 2M, RX PHY LE 2M LE conn param req: int (0x0018, 0x0028) lat 0 to 42 LE conn param updated: int 0x0028 lat 0 to 42
You can list the active connections of the shell using the
bt connections command. The shell
maximum number of connections is defined by
CONFIG_BT_MAX_CONN. You can disconnect
from a connection with the
bt disconnect <address: XX:XX:XX:XX:XX:XX> <type: (public|random)> command.
If you were scanning just before, you can connect to the last scanned device by
simply running the
bt connect command.
Alternatively, you can use the
bt connect-name <name> command to automatically
enable scanning with a name filter and connect to the first match.
Begin advertising by using the
bt advertise on command. This will use the default parameters
and advertise a resolvable private address with the name of the device. You can choose to use the
identity address instead by running the
bt advertise on identity command. To stop
advertising use the
bt advertise off command.
To enable more advanced features of advertising, you should create an advertiser using the
bt adv-create command. Parameters for the advertiser can be passed either at the creation of
it or by using the
bt adv-param command. To begin advertising with this newly created
advertiser, use the
bt adv-start command, and then the
bt adv-stop command to stop
When using the custom advertisers, you can choose if it will be connectable or scannable. This leads
to four options:
Those parameters are mandatory when creating an advertiser or updating its parameters.
For example, if you want to create a connectable and scannable advertiser and start it:
uart:~$ bt adv-create conn-scan Created adv id: 0, adv: 0x200022f0 uart:~$ bt adv-start Advertiser 0x200022f0 set started
You may notice that with this, the custom advertiser does not advertise the device name; you need to enable it. Continuing from the previous example:
uart:~$ bt adv-stop Advertiser set stopped uart:~$ bt adv-param conn-scan name uart:~$ bt adv-start Advertiser 0x200022f0 set started
You should now see the name of the device in the advertising data. You can also set the advertising
data manually by using the
bt adv-data command. The following example shows how to set the
advertiser name with it:
uart:~$ bt adv-create conn-scan Created adv id: 0, adv: 0x20002348 uart:~$ bt adv-data 1009426C7565746F6F74682D5368656C6C uart:~$ bt adv-start Advertiser 0x20002348 set started
The data must be formatted according to the Bluetooth Core Specification (see version 5.3, vol. 3,
part C, 11). In this example, the first octet is the size of the data (the data and one octet for
the data type), the second one is the type of data,
0x09 is the Complete Local Name and the
remaining data are the name in ASCII. So, on the other device you should see the name
When advertising, if others devices use an active scanner, you may receive scan request packets.
To visualize those packets, you can add
scan-reports to the parameters of your advertiser.
It is possible to use directed advertising on the shell if you want to reconnect to a device. The
following example demonstrates how to create a directed advertiser with the address specified right
after the parameter
low parameter indicates that we want to use the
low duty cycle mode, and the
dir-rpa parameter is required if the remote device is
privacy-enabled and supports address resolution of the target address in directed advertisement.
uart:~$ bt adv-create conn-scan directed D7:54:03:CE:F3:B4 random low dir-rpa Created adv id: 0, adv: 0x20002348
After that, you can start the advertiser and then the target device will be able to reconnect.
Let’s now have a look at some extended advertising features. To enable extended advertising, use the ext-adv parameter.
uart:~$ bt adv-create conn-nscan ext-adv name-ad Created adv id: 0, adv: 0x200022f0 uart:~$ bt adv-start Advertiser 0x200022f0 set started
This will create an extended advertiser, that is connectable and non-scannable.
Filter Accept List
It’s possible to create a list of allowed addresses that can be used to connect to those addresses automatically. Here is how to do it:
uart:~$ bt fal-add 47:38:76:EA:29:36 random uart:~$ bt fal-add 66:C8:80:2A:05:73 random uart:~$ bt fal-connect on
The shell will then connect to the first available device. In the example, if both devices are advertising at the same time, we will connect to the first address added to the list.
The Filter Accept List can also be used for scanning or advertising by using the option
For example, if we want to scan for a bunch of selected addresses, we can set up a Filter Accept
uart:~$ bt fal-add 65:4B:9E:83:AF:73 random uart:~$ bt fal-add 73:72:82:B4:8F:B9 random uart:~$ bt fal-add 5D:85:50:1C:72:64 random uart:~$ bt scan on fal
You should see only those three addresses reported by the scanner.
When connected to a device, you can enable multiple levels of security, here is the list for Bluetooth LE:
1 No encryption and no authentication;
2 Encryption and no authentication;
3 Encryption and authentication;
4 Bluetooth LE Secure Connection.
To enable security, use the
bt security <level> command. For levels requiring authentication
(level 3 and above), you must first set the authentication method. To do it, you can use the
bt auth all command. After that, when you will set the security level, you will be asked to
confirm the passkey on both devices. On the shell side, do it with the command
Enabling authentication requires the devices to be bondable. By default the shell is bondable. You
can make the shell not bondable using
bt bondable off. You can list all the devices you are
paired with using the command
The maximum number of paired devices is set using
CONFIG_BT_MAX_PAIRED. You can
remove a paired device using
bt clear <address: XX:XX:XX:XX:XX:XX> <type: (public|random)>
or remove all paired devices with the command
bt clear all.
The following examples assume that you have two devices already connected.
To perform service discovery on the client side, use the
gatt discover command. This should
print all the services that are available on the GATT server.
On the server side, you can register pre-defined test services using the
command. When done, you should see the newly added services on the client side when running the
You can now subscribe to those new services on the client side. Here is an example on how to subscribe to the test service:
uart:~$ gatt subscribe 26 25 Subscribed
The server can now notify the client with the command
Another option available through the GATT command is initiating the MTU exchange. To do it, use the
gatt exchange-mtu command. To update the shell maximum MTU, you need to update Kconfig
symbols in the configuration file of the shell. For more details, see
Bluetooth: MTU Update.
l2cap command exposes parts of the L2CAP API. The following example shows how to
register a LE PSM, connect to it from another device and send 3 packets of 14 octets each.
The example assumes that the two devices are already connected.
On device A, register the LE PSM:
uart:~$ l2cap register 29 L2CAP psm 41 sec_level 1 registered
On device B, connect to the registered LE PSM and send data:
uart:~$ l2cap connect 29 Chan sec: 1 L2CAP connection pending Channel 0x20000210 connected Channel 0x20000210 status 1 uart:~$ l2cap send 3 14 Rem 2 Rem 1 Rem 0 Outgoing data channel 0x20000210 transmitted Outgoing data channel 0x20000210 transmitted Outgoing data channel 0x20000210 transmitted
On device A, you should have received the data:
Incoming conn 0x20002398 Channel 0x20000210 status 1 Channel 0x20000210 connected Channel 0x20000210 requires buffer Incoming data channel 0x20000210 len 14 00000000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff |........ ...... | Channel 0x20000210 requires buffer Incoming data channel 0x20000210 len 14 00000000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff |........ ...... | Channel 0x20000210 requires buffer Incoming data channel 0x20000210 len 14 00000000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff |........ ...... |
You can configure the logging level per module at runtime. This depends on the maximum logging level
that is compiled in. To configure, use the
log command. Here are some examples:
List the available modules and their current logging level
uart:~$ log status
Disable logging for bt_hci_core
uart:~$ log disable bt_hci_core
Enable error logs for bt_att and bt_smp
uart:~$ log enable err bt_att bt_smp
Disable logging for all modules
uart:~$ log disable
Enable warning logs for all modules
uart:~$ log enable wrn