Skip to content

Bluetooth Low Energy: Observer

Overview

The Bluetooth Low Energy Observer sample demonstrates Bluetooth Low Energy Observer role functionality. The sample will periodically scan for devices nearby. If any found, prints the address of the device, the RSSI value, the Advertising type, and the Advertising data length to the console.

If the used Bluetooth Low Energy Controller supports Extended Scanning, you may enable CONFIG_BT_EXT_ADV in the project configuration file. Refer to the project configuration file for further details.

Requirements

Before you start, check that you have the required hardware and software:

  • 1x nRF54L15 Connect Kit
  • 1x U.FL cabled 2.4 GHz Antenna (included in the box)
  • 1x USB-C Cable
  • A computer running macOS, Ubuntu, or Windows 10 or newer

Attaching the 2.4 GHz antenna

Before applying power to the board, ensure the U.FL cabled 2.4 GHz antenna is properly installed.

Building the sample

To build the sample, follow the instructions in Getting Started Guide to set up your preferred building environment.

Use the following steps to build the Observer sample on the command line.

  1. Open a terminal window.

  2. Go to NCS-Project/nrf54l15-connectkit repository cloned in the Getting Started Guide.

  3. Build the sample using the west build command, specifying the board (following the -b option) as nrf54l15_connectkit/nrf54l15/cpuapp.

    west build -p always -b nrf54l15_connectkit/nrf54l15/cpuapp samples/bluetooth/observer

    west build -p always -b nrf54l15_connectkit/nrf54l15/cpuapp samples/bluetooth/observer -- -DCONF_FILE="prj_extended.conf"

    Tip

    The -p always option forces a pristine build, and is recommended for new users. Users may also use the -p auto option, which will use heuristics to determine if a pristine build is required, such as when building another sample.

  4. After building the sample successfully, the firmware with the name merged.hex can be found in the build directory.

Flashing the firmware

Connect the nRF54L15 Connect Kit to the computer with a USB-C cable:

Then flash the sample using west flash:

west flash

Tip

In case you wonder, the west flash will execute the following command:

pyocd load --target nrf54l --frequency 4000000 build/merged.hex

Testing

After programming the sample, test it by performing the following steps:

  1. Open up a serial terminal, specifying the primary COM port that your computer uses to communicate with the nRF54L15:

    1. Start PuTTY.

    2. Configure the correct serial port and click Open:

    Open up a terminal and run:

    screen <serial-port-name> 115200

    Open up a terminal and run:

    screen <serial-port-name> 115200

  2. Press the DFU/RST button to reset the nRF54L15.

  3. Observe the output of the terminal. You should see the output, similar to what is shown in the following:

    Terminal
     1
 2
 3
 4
 5
 6
 7
 8
 9
10
    *** Booting nRF Connect SDK v3.1.0-6c6e5b32496e ***
*** Using Zephyr OS v4.1.99-1612683d4010 ***
Starting Observer Demo
Started scanning...
Exiting main thread.
Device found: 5D:AB:ED:FA:8A:D5 (random) (RSSI -51), type 0, AD data len 30
Device found: 68:E4:78:39:7E:11 (public) (RSSI -66), type 0, AD data len 31
Device found: A4:C1:38:9C:59:F2 (public) (RSSI -62), type 0, AD data len 17
Device found: 73:87:FF:83:73:8B (random) (RSSI -75), type 0, AD data len 19
...
    Terminal
     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
    *** Booting nRF Connect SDK v3.1.0-6c6e5b32496e ***
*** Using Zephyr OS v4.1.99-1612683d4010 ***
Starting Observer Demo
Started scanning...
Exiting main thread.
Device found: 5C:31:F6:32:10:26 (random) (RSSI -39), type 0, AD data len 17
[DEVICE]: 5C:31:F6:32:10:26 (random), AD evt type 0, Tx Pwr: 127, RSSI -39 Data status: 0, AD data len: 17 Name:  C:1 S:1 D:0 SR:0 E:0 Pri PHY: LE 1M, Sec PHY: No packets, Interval: 0x0000 (0 ms), SID: 255
Device found: 68:E4:78:39:7E:11 (public) (RSSI -64), type 0, AD data len 31
[DEVICE]: 68:E4:78:39:7E:11 (public), AD evt type 0, Tx Pwr: 127, RSSI -64 Data status: 0, AD data len: 31 Name: U-RFR7E10 C:1 S:1 D:0 SR:0 E:0 Pri PHY: LE 1M, Sec PHY: No packets, Interval: 0x0000 (0 ms), SID: 255
Device found: 40:2A:8F:4E:93:81 (public) (RSSI -90), type 0, AD data len 27
[DEVICE]: 40:2A:8F:4E:93:81 (public), AD evt type 0, Tx Pwr: 127, RSSI -90 Data status: 0, AD data len: 27 Name:  C:1 S:1 D:0 SR:0 E:0 Pri PHY: LE 1M, Sec PHY: No packets, Interval: 0x0000 (0 ms), SID: 255
...