Connect to BLE on Raspberry Pi 4

Learn how to use Bluetooth Low Energy (BLE) on a virtual Raspberry Pi 4 and Android devices.

In this guide, we show how to communicate between two virtual Raspberry Pi 4 virtual boards as well as between a virtual Raspberry Pi 4 board and a virtual Android device.

Use BLE Between Two Raspberry Pi Devices

In this example, we will set up a Raspberry Pi 4 BLE Node and a Raspberry Pi 4 BLE Master.

Set Up the Raspberry Pi 4 BLE Node

To set up the Raspberry Pi 4 BLE node, do the following:

Create a Raspberry Pi 4 device. In this example we will use the "lite" stock firmware, and name the device "RPi-RPi BLE Node". After device is created, log in using the default credentials (pi/raspberry). Quickstart for Raspberry Pi 4 explains this step in more details.
Open the Bluetooth control tool.
```
bluetoothctl
```
Turn on Bluetooth.
```
power on
```
Open the advertise menu.
```
menu advertise
```
Set the manufacturer to 0xffff 0x12 0x34 then read back the values.
```
manufacturer 0xffff 0x12 0x34
manufacturer
```
Set the name to avh-demo-1 then read back the value.
```
name avh-demo-1
name
```
Go back to the main menu.
```
back
```
Open the generic attributes menu.
```
menu gatt
```

register-service e2d36f99-8909-4136-9a49-d825508b297b

Register a new read-only characteristic. In our example, we will enter 07 at the prompt.
```
register-characteristic 0x1234 read
```
Register a new read-write characteristic. In our example, we will enter 13 at the prompt.
```
register-characteristic 0x5678 read,write
```
Register the application. You should see a response Application Registered.
```
register-application
```
Go back to the main menu again.
```
back
```
Turn on advertising.
```
advertise on
```
Your Bluetooth node is now set up. Proceed to the next step to connect to this node using a second Raspberry Pi 4 board.

Connect to the Node with the Raspberry Pi 4 BLE Master

To connect to the node with the Raspberry Pi 4 BLE master, do the following:

Create a new Raspberry Pi 4 instance using the lite firmware. In our example, we will use the name "RPi-RPi BLE Master".
Open the Bluetooth control tool.
```
bluetoothctl
```
Turn on Bluetooth.
```
power on
```
Scan for Bluetooth devices.
```
scan on
```
Connect to the avh-demo-1 device. Make note of the two IDs starting with 00001234 and 00005678, referring to the custom characteristics that you set up.
```
connect 3E:A3:EC:CE:B1:61
```
Open the generic attributes menu.
```
menu gatt
```
Select the read-only attribute with an ID starting with 00001234. The prompt should change to the appropriate characteristic.
```
select-attribute 00001234-0000-1000-8000-00805f9b34fb
```
Read the value. You should see the value you set previously, represented in hexidecimal.
```
read
```
Attempt to write a new value. You should see an error because the characteristic is read-only.
```
write 1234
```
Select the read-write characteristic with an ID starting with 00005678. The prompt should change to the appropriate characteristic.
```
select-attribute 00005678-0000-1000-8000-00805f9b34fb
```
Read the value. You should see the value you set previously, represented in hexidecimal.
```
read
```
Write a new value then read it back. In our example, we will use 14, which is 0d in hexidecimal.
```
write 14
read
```

Use BLE Between a Raspberry Pi 4 Board and an Android Device

In this example, we will set up a Raspberry Pi 4 BLE Node and an Android BLE Master.

Set Up the Raspberry Pi 4 BLE Node

To set up the Raspberry Pi 4 BLE node, do the following:

Create a new Raspberry Pi 4 board. In our example, we will use the name "RPi-Android BLE Node".

Follow the steps in the previous section to set up a Raspberry Pi BLE Node. For our example, we will set the name of the Bluetooth node to "avh-demo-2".

bluetoothctl
power on
menu advertise
manufacturer 0xffff 0x12 0x34
name avh-demo-2
back
menu gatt
register-service e2d36f99-8909-4136-9a49-d825508b297b
yes
register-characteristic 0x1234 read
07
register-characteristic 0x5678 read,write
13
register-application
back
advertise on

When the node is advertising, make note of the node's MAC address on the first line of the response (3E:A3:EC:AE:72:9A in our example).

Connect to the Node with the Android BLE Master

To connect to the node with the Android BLE master, do the following:

Create a new Android device running firmware 12.0.0. For our example, we will use the name "RPi-Android BLE Master".
Download the Bluetooth LE Scanner APK to your local computer then install the APK through the Apps tab.
Open the Bluetooth LE Scanner app and click Scan. You should see avh-demo-2 appear with the matching MAC address.
Click on avh-demo-2 to open up additional details. Scroll to the bottom of the page to see the manufacturer [ff, ff, 12, 34] we set previously.
Click the CONNECT button in the Android app.
After the device connects successfully, you will see an Unknown Service with the ID matching what we set up. Expand the service.
You will see the two custom characteristics 1234 and 5678 that we set up.
Click on the 1234 and the 5678 services to see the values we had set previously (07 and 0d, respectively).