Bluetooth: Peripheral CTS client

The Peripheral CTS client sample demonstrates how to use the GATT Current Time Service (CTS) Client.

Requirements

The sample supports the following development kits:

Hardware platforms

PCA

Board name

Board target

nRF54L15 DK

PCA10156

nrf54l15dk

nrf54l15dk/nrf54l15/cpuapp

nRF54H20 DK

PCA10175

nrf54h20dk

nrf54h20dk/nrf54h20/cpuapp

nRF5340 DK

PCA10095

nrf5340dk

nrf5340dk/nrf5340/cpuapp/ns nrf5340dk/nrf5340/cpuapp

nRF52 DK

PCA10040

nrf52dk

nrf52dk/nrf52832

nRF52840 DK

PCA10056

nrf52840dk

nrf52840dk/nrf52840

When built for a board target with the */ns variant, the sample is configured to compile and run as a non-secure application with Cortex-M Security Extensions enabled. Therefore, it automatically includes Trusted Firmware-M that prepares the required peripherals and secure services to be available for the application.

The sample also requires a device running a CTS Server to connect with (for example, a Bluetooth® Low Energy dongle and nRF Connect for Desktop).

Overview

The CTS client sample implements a Current Time Service client. It uses the Current Time Service to read the current time. The time received is printed on the UART.

User interface

LED 1:

Blinks, toggling on/off every second, when the main loop is running and the device is advertising.

LED 2:

Lit when connected.

Button 1:

Read the current time.

Building and running

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

When built as firmware image for a board target with the */ns variant, the sample has Cortex-M Security Extensions (CMSE) enabled and separates the firmware between Non-Secure Processing Environment (NSPE) and Secure Processing Environment (SPE). Because of this, it automatically includes the Trusted Firmware-M (TF-M). To read more about CMSE, see Processing environments.

To build the sample, follow the instructions in Building an application for your preferred building environment. See also Programming an application for programming steps and Testing and optimization for general information about testing and debugging in the nRF Connect SDK.

Note

When building repository applications in the SDK repositories, building with sysbuild is enabled by default. If you work with out-of-tree freestanding applications, you need to manually pass the --sysbuild parameter to every build command or configure west to always use it.

Testing

After programming the sample to your development kit, you can test it with nRF Connect for Desktop by performing the following steps.

  1. Connect to the kit that runs this sample with a terminal emulator (for example, nRF Connect Serial Terminal). See Testing and optimization for the required settings and steps.

  2. Reset the kit.

  3. Start nRF Connect for Desktop

  4. Open the Bluetooth Low Energy app and select the connected dongle that is used for communication.

  5. Open the SERVER SETUP tab. Click the dongle configuration and select Load setup. Load the cts_central.ncs file that is located under samples/bluetooth/peripheral_cts_client in the nRF Connect SDK folder structure.

  6. Click Apply to device.

  7. Open the CONNECTION MAP tab. Click the dongle configuration and select Security parameters. Check Perform Bonding, and click Apply.

  8. Set the value of Current Time Service > Current Time to C2 07 0B 0F 0C 22 38 06 80 02 and click Write.

  9. Connect to the device from the app. The device is advertising as “Nordic_CTS”.

  10. Wait until the bond is established. Verify that the UART data is received as follows:

    Connected xx:xx:xx:xx:xx:xx (random)
The discovery procedure succeeded
Security changed: xx:xx:xx:xx:xx:xx (random) level 2
Pairing completed: xx:xx:xx:xx:xx:xx (random), bonded: 1

  11. Press Button 1 on the kit. Verify that the current time printed on the UART matches the time that was input in the Current Time characteristic (UUID 0x2A2B):

    Current Time:

Date:
   Day of week   Saturday
   Day of month  15
   Month of year November
   Year          1986

Time:
   Hours     12
   Minutes   34
   Seconds   56
   Fractions 128/256 of a second

Adjust Reason:
   Daylight savings 0
   Time zone        0
   External update  1
   Manual update    0

  12. Change the value of Current Time Service > Current Time to C2 07 0B 0F 0D 25 2A 06 FE 08. It generates a notification. Verify that the current time printed on the UART matches the time that was input:

    Current Time:

Date:
   Day of week   Saturday
   Day of month  15
   Month of year November
   Year          1986

Time:
   Hours     13
   Minutes   37
   Seconds   42
   Fractions 254/256 of a second

Adjust Reason:
   Daylight savings 1
   Time zone        0
   External update  0
   Manual update    0

  13. Disconnect the device in the Bluetooth Low Energy app.

  14. As bond information is preserved by the Bluetooth Low Energy app, you can immediately reconnect to the device by clicking the Connect button again.

Dependencies

This sample uses the following nRF Connect SDK libraries:

In addition, it uses the following Zephyr libraries:

  • include/zephyr/types.h

  • lib/libc/minimal/include/errno.h

  • include/sys/printk.h

  • API:

    • include/bluetooth/bluetooth.h

    • include/bluetooth/conn.h

    • include/bluetooth/uuid.h

    • include/bluetooth/gatt.h

The sample also uses the following secure firmware component: