Skip to content

Bluetooth Low Energy: Channel Sounding

Overview

This section provides instructions on utilizing the Bluetooth® Low Energy (BLE) Channel Sounding feature, which enables high-precision ranging measurements between devices. The feature involves two primary roles: Initiator with Ranging Requestor and Reflector with Ranging Responder.

  • Initiator with Ranging Requestor

    Act as a GATT Ranging Requestor client and configures the Channel Sounding initiator role.

    View Code

  • Reflector with Ranging Responder

    Expose the GATT Ranging Responder Service and configures the Channel Sounding reflector role.

    View Code

Requirements

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

  • 2x nRF54L15 Connect Kit with U.FL cabled 2.4 GHz Antenna
  • 2x 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 samples

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

Use the following steps to build the Initiator with Ranging Requestor and Reflector with Ranging Responder samples 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/channel_sounding_ras_initiator

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

    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 one device with the initiator application, and another device with the reflector application:

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 initiator and the reflector, test them by performing the following steps:

  1. Open up a serial terminal for each device, 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
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
    *** Booting nRF Connect SDK v3.1.0-6c6e5b32496e ***
*** Using Zephyr OS v4.1.99-1612683d4010 ***
I: Starting Channel Sounding Initiator Sample
I: SoftDevice Controller build revision:
I: fc de 41 eb a2 d1 42 24 |..A...B$
I: 00 b5 f8 57 9f ac 9d 9e |...W....
I: aa c9 b4 34             |...4
I: HW Platform: Nordic Semiconductor (0x0002)
I: HW Variant: nRF54Lx (0x0005)
I: Firmware: Standard Bluetooth controller (0x00) Version 252.16862 Build 1121034987
I: HCI transport: SDC
I: Identity: EF:11:48:A5:EA:6D (random)
I: HCI: version 6.1 (0x0f) revision 0x3069, manufacturer 0x0059
I: LMP: version 6.1 (0x0f) subver 0x3069
I: Filters matched. Address: F4:3D:C2:1E:6E:74 (random) connectable: 1
I: Connecting
I: Connected to F4:3D:C2:1E:6E:74 (random) (err 0x00)
I: Security changed: F4:3D:C2:1E:6E:74 (random) level 2
I: MTU exchange success (498)
I: The discovery procedure succeeded
I: Read RAS feature bits: 0x1
I: CS capability exchange completed.
I: CS config creation complete. ID: 0
I: CS security enabled.
I: CS procedures enabled:
- config ID: 0
- antenna configuration index: 0
- TX power: 0 dbm
- subevent length: 28198 us
- subevents per event: 1
- subevent interval: 0
- event interval: 2
- procedure interval: 5
- procedure count: 0
- maximum procedure length: 1000
I: Distance estimates on antenna path 0: ifft: 1.610213, phase_slope: 2.249911, rtt: 13.750394
I: Sleeping for a few seconds...
I: Distance estimates on antenna path 0: ifft: 1.756596, phase_slope: 2.404551, rtt: 13.855685
I: Sleeping for a few seconds...
I: Distance estimates on antenna path 0: ifft: 1.756596, phase_slope: 2.046242, rtt: 13.543401
I: Sleeping for a few seconds...
I: Distance estimates on antenna path 0: ifft: 1.756596, phase_slope: 2.150647, rtt: 13.648731
I: Sleeping for a few seconds...
...
    Terminal
     1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
    *** Booting nRF Connect SDK v3.1.0-6c6e5b32496e ***
*** Using Zephyr OS v4.1.99-1612683d4010 ***
I: Starting Channel Sounding Reflector Sample
I: SoftDevice Controller build revision:
I: fc de 41 eb a2 d1 42 24 |..A...B$
I: 00 b5 f8 57 9f ac 9d 9e |...W....
I: aa c9 b4 34             |...4
I: HW Platform: Nordic Semiconductor (0x0002)
I: HW Variant: nRF54Lx (0x0005)
I: Firmware: Standard Bluetooth controller (0x00) Version 252.16862 Build 1121034987
I: HCI transport: SDC
I: Identity: EF:11:48:A5:EA:6D (random)
I: HCI: version 6.1 (0x0f) revision 0x3069, manufacturer 0x0059
I: LMP: version 6.1 (0x0f) subver 0x3069
I: Connected to EF:11:48:A5:EA:6D (random) (err 0x00)
I: CS capability exchange completed.
I: CS config creation complete. ID: 0
I: CS security enabled.
I: CS procedures enabled.
...