Bluetooth: Peripheral LBS

The peripheral LBS sample demonstrates how to use the LED Button Service (LBS).

Overview

When connected, the sample sends the state of Button 1 on the development kit to the connected device, such as a phone or tablet. The mobile application on the device can display the received button state and can control the state of LED 3 on the development kit.

Alternatively, you can use this sample to control the color of the RGB LED on the nRF52840 Dongle or Thingy:53.

Requirements

The sample supports the following development kits:

Hardware platforms	PCA	Board name	Build target
nRF5340 DK	PCA10095	nrf5340dk_nrf5340	nrf5340dk_nrf5340_cpuapp nrf5340dk_nrf5340_cpuapp_ns
nRF52840 DK	PCA10056	nrf52840dk_nrf52840	nrf52840dk_nrf52840
nRF52840 DK (emulating nRF52811)	PCA10056	nrf52840dk_nrf52811	nrf52840dk_nrf52811
nRF52833 DK	PCA10100	nrf52833dk_nrf52833	nrf52833dk_nrf52833
nRF52833 DK (emulating nRF52820)	PCA10100	nrf52833dk_nrf52820	nrf52833dk_nrf52820
nRF52 DK	PCA10040	nrf52dk_nrf52832	nrf52dk_nrf52832
nRF52 DK (emulating nRF52810)	PCA10040	nrf52dk_nrf52810	nrf52dk_nrf52810
nRF52840 Dongle	PCA10059	nrf52840dongle_nrf52840	nrf52840dongle_nrf52840
Thingy:53	PCA20053	thingy53_nrf5340	thingy53_nrf5340_cpuapp thingy53_nrf5340_cpuapp_ns

The sample also requires a smartphone or tablet running a compatible application. The Testing instructions refer to nRF Connect for Mobile, but you can also use other similar applications (for example, nRF Blinky or nRF Toolbox).

Note

If you build this application for Thingy:53, it enables additional features. See Thingy:53 application guide for details.

User interface

The user interface of the sample depends on the hardware platform you are using.

nRF52840 Dongle

Green LED:

When the main loop is running (that is, the device is advertising), the LED blinks with a period of 2 seconds, duty cycle 50%.

RGB LED:

The RGB LED channels are used independently to display the following information:

• Red - if Dongle is connected.

• Green - if user set the LED using Nordic LED Button Service.

Button 1:

Send a notification with the button state: “pressed” or “released”.

Thingy:53

RGB LED:

The RGB LED channels are used independently to display the following information:

• Red - if the main loop is running (that is, the device is advertising). The LED blinks with a period of 2 seconds, duty cycle 50%.

• Green - if the device is connected.

• Blue - if user set the LED using Nordic LED Button Service.

For example, if Thingy:53 is connected over Bluetooth, the LED color toggles between green and yellow. The green LED channel is kept on and the red LED channel is blinking.

Button 1:

Send a notification with the button state: “pressed” or “released”.

Development kits

LED 1:

Blinks when the main loop is running (that is, the device is advertising) with a period of 2 seconds, duty cycle 50%.

LED 2:

On when the development kit is connected.

LED 3:

On when the development kit is controlled remotely from the connected device.

Button 1:

Send a notification with the button state: “pressed” or “released”.

Building and running

This sample can be found under samples/bluetooth/peripheral_lbs in the nRF Connect SDK folder structure.

See Building and programming an application for information about how to build and program the application.

Minimal build

You can build the sample with a minimum configuration as a demonstration of how to reduce code size and RAM usage, using the -DCONF_FILE='prj_minimal.conf' flag in your build.

See Providing CMake options for instructions on how to add this option to your build. For example, when building on the command line, you can do so as follows:

west build samples/bluetooth/peripheral_lbs -- -DCONF_FILE='prj_minimal.conf'

Testing

After programming the sample to your dongle or development kit, test it by performing the following steps:

1. Start the nRF Connect for Mobile application on your smartphone or tablet.

2. Power on the development kit or insert your dongle into the USB port.

3. Connect to the device from the nRF Connect application. The device is advertising as Nordic_LBS. The services of the connected device are shown.

4. In Nordic LED Button Service, enable notifications for the Button characteristic.

5. Press Button 1 on the device.

6. Observe that notifications with the following values are displayed:

   • Button released when Button 1 is released.

   • Button pressed when Button 1 is pressed.

7. Write the following values to the LED characteristic in the Nordic LED Button Service. Depending on the hardware platform, this produces results described in the table.

Hardware platform	Value	Effect
Development kit	OFF	Switch the LED3 off.
	ON	Switch the LED3 on.
nRF52840 Dongle	OFF	Switch the green channel of the RGB LED off.
	ON	Switch the green channel of the RGB LED on.
Thingy:53	OFF	Switch the blue channel of the RGB LED off.
	ON	Switch the blue channel of the RGB LED on.

Dependencies

This sample uses the following nRF Connect SDK libraries:

• LED Button Service (LBS)

• DK Buttons and LEDs

In addition, it uses the following Zephyr libraries:

• include/zephyr/types.h

• lib/libc/minimal/include/errno.h

• include/sys/printk.h

• include/sys/byteorder.h

• GPIO Interface

• Bluetooth:

  • include/bluetooth/bluetooth.h

  • include/bluetooth/hci.h

  • include/bluetooth/conn.h

  • include/bluetooth/uuid.h

  • include/bluetooth/gatt.h