nRF52 Series Devices

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On the nRF52 series devices from Nordic Semiconductor, SWO is supported. However, a few device specifics apply which are described in the following section.

Clock source

For most devices, the SWO clock is derived from the current MCU clock. This is also the case for the nRF52 series devices. However on these devices, the SWO clock has an additional fixed divider. So when the MCU Clock is set to maximum 64 MHz the SWO clock is only maximum half of that which is 32 MHz. Depending of the setting in the TRACECONFIG register, this value can get divided down even further.

Note: J-Link handles the current setting of this register automatically when calculating the SWO speed to be used. J-Link software version V6.30i or later is required.

Note: When selecting the CPU frequency in IDEs for J-Link SWO usage, select 64 MHz for the nRF52 series devices.

Sample projects

Sample projects that demonstrate SWO usage are available for the following eval board: PCA10040

This project was created with Embedded Studio V3.40. The SWO print stream can be made visible by either using JLinkSWOViewer or Ozone with the project enclosed in the Embedded Studio project.


Nordic Semiconductor offers a so called softdevice which acts like a boot loader for Bluetooth related communication on ther nRF device series. If a application is programmed that is using softdevice API you will need to download the softdevice first before downloading your application.

Sample project

The latest Nordic nRF5 SDK contains numerous example projects which work out-of-the-box with Embedded Studio. In these the softdevice loading is handled automatically. To be able to use Ozone now the PC and SP must be set correctly on the bootloader/softdevice that is programmed: Start debug session with bootloader

An example Ozone project for SDK application "ble_app_blinky" for the PCA10040 eval board can be found here: Ozone project