> ## Documentation Index
> Fetch the complete documentation index at: https://dragonwingdocs.qualcomm.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Perform Bluetooth Low Energy GATT client functions

> You can perform Bluetooth Low Energy GATT client functions using the **GATT submenu** options and ``bluetoothctl`` commands. Bluetooth Low Energy GATT client functions include connecting to a remote device and starting or stopping Bluetooth Low Energy GATT scans. You can retrieve the list of attributes, get attribute information, and select specific attributes. GATT functions also support reading and writing characteristic values, including encrypted characteristics, and reading and writing descriptor values. Additionally, they allow turning notifications on or off for selected attributes.

## Prerequisites

Before you begin, set up the device as described in <a href="verify-gatt-functions#set-up-the-device-for-bluetooth-low-energy-gatt-functions" target="_self">Set up the device for Bluetooth Low Energy GATT functions</a>.

## Connect to a remote device

To connect to a remote device, run the following command from the `bluetoothctl` menu:

```text theme={null}
connect <bt_address>
```

**Parameters**

`<bt_address>` is the Bluetooth address of the remote device.

<Note>
  To get the Bluetooth address of the remote device, run a <a href="#stop-bluetooth-low-energy-gatt-scan" target="_self">Bluetooth Low Energy GATT scan</a>.
</Note>

**Example**

To connect to a server device with `<bt_address>` `6D:38:AF:C6:B5:62`, run the following command:

```text theme={null}
connect 6D:38:AF:C6:B5:62
```

**Sample output**

```text theme={null}
[bluetooth]# connect 6D:38:AF:C6:B5:62
Attempting to connect to 6D:38:AF:C6:B5:62
[CHG] Device 6D:38:AF:C6:B5:62 Connected: yes
Connection successful
[NEW] Primary Service (Handle 0x0000)
      /org/bluez/hci0/dev_6D_38_AF_C6_B5_62/service0001
      00001801-0000-1000-8000-00805f9b34fb
      Generic Attribute Profile
[NEW] Characteristic (Handle 0x0000)
      /org/bluez/hci0/dev_6D_38_AF_C6_B5_62/service0001/char0002
      00002a05-0000-1000-8000-00805f9b34fb
      Service Changed
[NEW] Characteristic (Handle 0x0000)
      /org/bluez/hci0/dev_6D_38_AF_C6_B5_62/service0001/char0004
      00002b3a-0000-1000-8000-00805f9b34fb
      Server Supported Features
[NEW] Characteristic (Handle 0x0000)
      /org/bluez/hci0/dev_6D_38_AF_C6_B5_62/service0001/char0006
      00002b29-0000-1000-8000-00805f9b34fb
      Client Supported Features
[NEW] Characteristic (Handle 0x0000)
      /org/bluez/hci0/dev_6D_38_AF_C6_B5_62/service0001/char0008
      00002b2a-0000-1000-8000-00805f9b34fb
      Database Hash
[CHG] Device 6D:38:AF:C6:B5:62 UUIDs: 00001800-0000-1000-8000-00805f9b34fb
[CHG] Device 6D:38:AF:C6:B5:62 UUIDs: 00001801-0000-1000-8000-00805f9b34fb
[CHG] Device 6D:38:AF:C6:B5:62 ServicesResolved: yes
```

## Start Bluetooth Low Energy GATT scan

To start a Bluetooth Low Energy GATT scan, run the following command from the `bluetoothctl` menu:

```text theme={null}
scan le
```

<Note>
  To get the scan results, the remote device must advertise using any Bluetooth Low Energy application.
</Note>

**Sample output**

```text theme={null}
[MyDeviceB]# scan le
Discovery started
[CHG] Controller 22:22:9B:2C:79:1E Discovering: yes
[CHG] Device F8:7D:76:9D:9B:6B RSSI: -70
[NEW] Device A4:30:7A:EE:AF:EF [TV] MyDeviceA (43)
[NEW] Device 52:2F:07:6F:AA:93 52-2F-07-6F-AA-93
[CHG] Device A4:30:7A:EE:AF:EF ManufacturerData Key: 0x0075
[CHG] Device A4:30:7A:EE:AF:EF ManufacturerData Value:
42 04 01 01 e7 a4 30 7a ee af ef a6 30 7a ee af B..... 0z....0z....
ee 01 3b 00 00 00 00 00                          ......
[CHG] Device A4:30:7A:EE:AF:EF Modalias: bluetooth:v04E8p8080d0000
[CHG] Device A4:30:7A:EE:AF:EF UUIDs: 0000110a-0000-1000-8000-00805f9b34fb
[CHG] Device A4:30:7A:EE:AF:EF UUIDs: 0000110b-0000-1000-8000-00805f9b34fb
[CHG] Device A4:30:7A:EE:AF:EF UUIDs: 0000110c-0000-1000-8000-00805f9b34fb
[CHG] Device A4:30:7A:EE:AF:EF UUIDs: 0000110e-0000-1000-8000-00805f9b34fb
[CHG] Device A4:30:7A:EE:AF:EF UUIDs: 00001112-0000-1000-8000-00805f9b34fb
[CHG] Device A4:30:7A:EE:AF:EF UUIDs: 0000111f-0000-1000-8000-00805f9b34fb
[CHG] Device A4:30:7A:EE:AF:EF UUIDs: 00001200-0000-1000-8000-00805f9b34fb
[CHG] Device A4:30:7A:EE:AF:EF ManufacturerData Key: 0x0075
[CHG] Device A4:30:7A:EE:AF:EF ManufacturerData Value:
42 04 01 01 e7 a4 30 7a ee af ef a6 30 7a ee af B..... 0z....0z....
ee 01 3b 00 00 00 00 00                          ......
[CHG] Device A4:30:7A:EE:AF:EF ManufacturerData Key: 0xff19
[CHG] Device A4:30:7A:EE:AF:EF ManufacturerData Value:
00 75 00 09 01 00 00 00 06 01 00 00 00 00 00 00 .u..................
00 00 00 00 00 00 00 00                         ................
[CHG] Device F8:7D:76:9D:9B:6B RSSI: -60
[CHG] Device A4:30:7A:EE:AF:EF ManufacturerData Key: 0x0075
[CHG] Device A4:30:7A:EE:AF:EF ManufacturerData Value:
42 04 01 20 e7 20 0d 00 02 01 2b 01 01 00 01 00 B .. ..... .......
00 00 00 00 00 00 00 00                        ........
[CHG] Device A4:30:7A:EE:AF:EF ManufacturerData Key: 0xff19
[CHG] Device A4:30:7A:EE:AF:EF ManufacturerData Value:
00 75 00 09 01 00 00 00 06 01 00 00 00 00 00 00  .u.............
00 00 00 00 00 00 00 00                            .......
[NEW] Device 4A:04:87:DF:CB:35 4A-04-87-DF-CB-35
[DEL] Device 52:2F:07:6F:AA:93 52-2F-07-6F-AA-93
```

## Stop Bluetooth Low Energy GATT scan

To stop a Bluetooth Low Energy GATT scan, run the following command from the `bluetoothctl` menu:

```text theme={null}
scan off
```

**Sample output**

```text theme={null}
[MyDeviceB]# scan off
Discovery stopped
[CHG] Device A4:30:7A:EE:AF:EF RSSI is nil
[CHG] Device F8:7D:76:9D:9B:6B RSSI is nil
[CHG] Controller 22:22:9B:2C:79:1E Discovering: no
```

## Get the list of attributes

To get the list of attributes of the remote device, run the following command from the `menu gatt` menu:

```text theme={null}
list-attributes <bt_address>
```

**Parameters**

`<bt_address>` is the address of the remote device.

**Example**

To list the attributes of the remote device with the address `6D:38:AF:C6:B5:62`, run the following command:

```text theme={null}
list-attributes 6D:38:AF:C6:B5:62
```

**Sample output**

```text theme={null}
[MyDeviceB]# list-attributes 6D:38:AF:C6:B5:62
Primary Service (Handle 0x0000)
      /org/bluez/hci0/dev_6D_38_AF_C6_B5_62/service0001
      00001801-0000-1000-8000-00805f9b34fb
      Generic Attribute Profile
Characteristic (Handle 0x0000)
      /org/bluez/hci0/dev_6D_38_AF_C6_B5_62/service0001/char0002
      00002a05-0000-1000-8000-00805f9b34fb
      Service Changed
Characteristic (Handle 0x0000)
      /org/bluez/hci0/dev_6D_38_AF_C6_B5_62/service0001/char0004
      00002b3a-0000-1000-8000-00805f9b34fb
      Server Supported Features
Characteristic (Handle 0x0000)
      /org/bluez/hci0/dev_6D_38_AF_C6_B5_62/service0001/char0006
      00002b29-0000-1000-8000-00805f9b34fb
      Client Supported Features
Characteristic (Handle 0x0000)
      /org/bluez/hci0/dev_6D_38_AF_C6_B5_62/service0001/char0008
      00002b2a-0000-1000-8000-00805f9b34fb
      Database Hash
```

## Get attribute information

To get the information of an attribute, run the following command from the `menu gatt` menu:

```text theme={null}
attribute-info <attribute/UUID>
```

**Parameters**

`<attribute/UUID>` is the UUID or the attribute path.

**Example**

To get the information of an attribute with the UUID `00002b29-0000-1000-8000-00805f9b34fb`, run the following command:

```text theme={null}
attribute-info 00002b29-0000-1000-8000-00805f9b34fb
```

**Sample output**

```text theme={null}
[MyDeviceB]# attribute-info 00002b29-0000-1000-8000-00805f9b34fb
Characteristic - Client Supported Features
      UUID: 00002b29-0000-1000-8000-00805f9b34fb
      Service: /org/bluez/hci0/dev_73_F4_3F_FA_0A_DF/service0001
      Flags: read
      Flags: write
      MTU: 0x0205
```

## Select an attribute

To select the attribute using the UUID or path, run the following command from the `menu gatt` menu:

```text theme={null}
select-attribute <attribute/UUID>
```

**Parameters**

`<attribute/UUID>` is the UUID or path of the attribute.

**Example**

* To select an attribute using the UUID `00006677-0000-1000-8000-00805f9b34fb`, run the following command:

  ```text theme={null}
  select-attribute 00006677-0000-1000-8000-00805f9b34fb
  ```

  **Sample output**

  ```text theme={null}
  Characteristic User Description
  [MyDeviceB]# select-attribute 00006677-0000-1000-8000-00805f9b34fb
  <lect-attribute 00006677-0000-1000-8000-00805f9b34fb[MyDeviceB:/service0028/char0029/desc002c]#
  [MyDeviceB:/service0028/char0029/desc002c]#
  ```

* To select an attribute using the attribute path `/org/bluez/hci0/dev_6C_5F_B9_ED_5B_48/service0001/char0002`, run the following command:

  ```text theme={null}
  select-attribute /org/bluez/hci0/dev_6C_5F_B9_ED_5B_48/service0001/char0002
  ```

  **Sample output**

  ```text theme={null}
  [MyDeviceB:/service0001/char0004]# ED_5B_48/service0001/char0002
  [MyDeviceB:/service0001/char0002]#
  ```

## Read a characteristic value

To read a characteristic value, do the following from the `menu gatt` menu:

1. <a href="#select-an-attribute" target="_self">Select the intended attribute.</a>

2. Read the selected attribute by running the following command:

   ```text theme={null}
   read 0
   ```

**Sample output**

```text theme={null}
[MyDeviceB:/service0028/char0029]# read 0
Attempting to read /org/bluez/hci0/dev_64_8C_C7_03_C4_B0/service0028/char0029
[CHG] Attribute /org/bluez/hci0/dev_64_8C_C7_03_C4_B0/service0028/char0029 Value:
   11
   11
[MyDeviceB:/service0028/char0029]#
```

## Write a characteristic value

To write a characteristic value, do the following from the `menu gatt` menu:

1. <a href="#select-an-attribute" target="_self">Select the intended attribute.</a>

2. Write a value to the selected attribute by running the following command:

   ```text theme={null}
   write "<value>"
   ```

   **Parameters**

   `<value>` is the value you intend to write.

   **Example**

   To write the attribute value as `0x11`, run the following command:

   ```text theme={null}
   write "0x11"
   ```

**Sample output**

```text theme={null}
[MyDeviceB:/service0028/char0029]# read 0b
Attempting to read /org/bluez/hci0/dev_64_8C_C7_03_C4_B0/service0028/char0029
[CHG] Attribute /org/bluez/hci0/dev_64_8C_C7_03_C4_B0/service0028/char0029 Value:
   22
   22
[MyDeviceB:/service0028/char0029]# write "0x11"
Attempting to write /org/bluez/hci0/dev_64_8C_C7_03_C4_B0/service0028/char0029
[MyDeviceB:/service0028/char0029]# read 0
Attempting to read /org/bluez/hci0/dev_64_8C_C7_03_C4_B0/service0028/char0029
[CHG] Attribute /org/bluez/hci0/dev_64_8C_C7_03_C4_B0/service0028/char0029 Value:
   11    
   11
[MyDeviceB:/service0028/char0029]#
```

## Read a descriptor value

To read a descriptor value, do the following from the `menu gatt` menu:

1. <a href="#select-an-attribute" target="_self">Select the intended attribute.</a>

2. Read the selected attribute by running the following command:

   ```text theme={null}
   read 0
   ```

**Sample output**

```text theme={null}
[MyDeviceB]# select-attribute 00006677-0000-1000-8000-00805f9b34fb
<lect-attribute 00006677-0000-1000-8000-00805f9b34fb[MyDeviceB:/service0028/char0029/desc002c]#
[MyDeviceB:/service0028/char0029/desc002c]#
[MyDeviceB:/service0028/char0029/desc002c]# read 0
Attempting to read /org/bluez/hci0/dev_55_B1_D2_67_7C_CD/service0028/char0029/desc002c
[CHG] Attribute /org/bluez/hci0/dev_55_B1_D2_67_7C_CD/service0028/char0029/desc002c Value:
   00
   00
[MyDeviceB:/service0028/char0029/desc002c]# write "0x11"
Attempting to write /org/bluez/hci0/dev_55_B1_D2_67_7C_CD/service0028/char0029/desc002c
[MyDeviceB:/service0028/char0829/desc002c]# read 0
Attempting to read /org/bluez/hci0/dev_55_B1_D2_67_7C_CD/service0028/char0029/desc002c
[CHG] Attribute /org/bluez/hci0/dev_55_B1_D2_67_7C_CD/service0028/char0029/desc002c Value:
   11
   11
[MyDeviceB:/service0028/char0029/desc002c]#
```

## Write a descriptor value

To write a descriptor value, do the following from the `menu gatt` menu:

1. <a href="#select-an-attribute" target="_self">Select the intended attribute.</a>

2. Write a value to the selected attribute by running the following command:

   ```text theme={null}
   write "<value>"
   ```

   **Parameters**

   `<value>` is the value you intend to write.

   **Example**

   To write the attribute value as `0x11`, run the following command:

   ```text theme={null}
   write "0x11"
   ```

**Sample output**

```text theme={null}
[MyDeviceB]# select-attribute 00006677-0000-1000-8000-00805f9b34fb
<lect-attribute 00006677-0000-1000-8000-00805f9b34fb[MyDeviceB:/service0028/char0029/desc002c]#
[MyDeviceB:/service0028/char0029/desc002c]#
[MyDeviceB:/service0028/char0029/desc002c]# read 0
Attempting to read /org/bluez/hci0/dev_55_B1_D2_67_7C_CD/service0028/char0029/desc002c
[CHG] Attribute /org/bluez/hci0/dev_55_B1_D2_67_7C_CD/service0028/char0029/desc002c Value:
   00
   00
[MyDeviceB:/service0028/char0029/desc002c]# write "0x11"
Attempting to write /org/bluez/hci0/dev_55_B1_D2_67_7C_CD/service0028/char0029/desc002c
[MyDeviceB:/service0028/char0829/desc002c]# read 0
Attempting to read /org/bluez/hci0/dev_55_B1_D2_67_7C_CD/service0028/char0029/desc002c
[CHG] Attribute /org/bluez/hci0/dev_55_B1_D2_67_7C_CD/service0028/char0029/desc002c Value:
   11
   11
[MyDeviceB:/service0028/char0029/desc002c]#
```

## Read an encrypted characteristic value

To read an encrypted characteristic value, do the following from the `menu gatt` menu:

1. <a href="#select-an-attribute" target="_self">Select the intended attribute.</a>

2. Read the selected attribute by running the following command:

   ```text theme={null}
   read 0
   ```

3. Enter `yes` when prompted to confirm the reading.

**Sample output**

```text theme={null}
[MyDeviceB:/service0028/char0029]# read 0
Attempting to read /org/bluez/hci0/dev_4F_A4_EC_0D_D2_F2/service0028/char0029
[DEL] Device 60:A3:37:5A:35:5F 60-A3-37-5A-35-5F
[NEW] Device 60:A3:37:5A:35:5F 60-A3-37-5A-35-5F
Request confirmation
[agent] Confirm passkey 161326 (yes/no): yes
[CHG] Attribute /org/bluez/hci0/dev_4F_A4_EC_0D_D2_F2/service0028/char0029 Value:
   00
[CHG] Device D4:8A:39:78:27:41 Address: D4:8A:39:78:27:41
[CHG] Device D4:8A:39:78:27:41 AddressType: public
   00
[CHG] Device D4:8A:39:78:27:41 Bonded: yes
[CHG] Device D4:8A:39:78:27:41 Paired: yes
[CHG] Device D4:8A:39:78:27:41 Class: 0x005a020c
[CHG] Device D4:8A:39:78:27:41 Icon: phone
```

## Write an encrypted characteristic value

To write an encrypted characteristic value, do the following from the `menu gatt` menu:

1. <a href="#select-an-attribute" target="_self">Select the intended attribute.</a>

2. Write a value to the selected attribute by running the following command:

   ```text theme={null}
   write "<value>"
   ```

   **Parameters**

   `<value>` is the value you intend to write.

   **Example**

   To write the attribute value as `0x11`, run the following command:

   ```text theme={null}
   write "0x11"
   ```

3. Enter `yes` when prompted to confirm writing.

## Turn on notifications for an attribute

To turn on notifications for an attribute, do the following from the `menu gatt` menu:

1. <a href="#select-an-attribute" target="_self">Select the intended attribute.</a>

2. Enable notifications for the attribute by running the following command:

   ```text theme={null}
   notify on
   ```

   You get notifications of any changes to the attribute.

**Sample output**

```text theme={null}
[MyDeviceB:/service0028/char0029]# notify on
[CHG] Attribute /org/bluez/hci0/dev_44_38_FB_67_B2_E2/service0028/char0029 Notifying: yes
Notify started
[CHG] Attribute /org/bluez/hci0/dev_44_38_FB_67_B2_E2/service0028/char0029 Value:
   55                                            U
[CHG] Attribute /org/bluez/hci0/dev_44_38_FB_67_B2_E2/service0028/char0029 Value:
   88                                            .
[CHG] Attribute /org/bluez/hci0/dev_44_38_FB_67_B2_E2/service0028/char0029 Value:
   55 55                                         UU
[CHG] Device D4:8A:39:78:27:41 RSSI: -74
[CHG] Attribute /org/bluez/hci0/dev_44_38_FB_67_B2_E2/service0028/char0029 Value:
   55                                            U
[CHG] Attribute /org/bluez/hci0/dev_44_38_FB_67_B2_E2/service0028/char0029 Value:
   11                                            U
[CHG] Attribute /org/bluez/hci0/dev_44_38_FB_67_B2_E2/service0028/char0029 Value:
   66                                            f
```

## Turn off notifications for an attribute

To turn off notifications for an attribute, do the following from the `menu gatt` menu:

1. <a href="#select-an-attribute" target="_self">Select the intended attribute.</a>

2. Disable notifications for the attribute by running the following command:

   ```text theme={null}
   notify off
   ```

**Sample output**

```text theme={null}
[MyDeviceB:/service0028/char0029]# notify off
[CHG] Attribute /org/bluez/hci0/dev_44_38_FB_67_B2_E2/service0028/char0029 Notifying: no
Notify stopped
```