Radio test

The Radio test sample demonstrates how to configure the radio in a specific mode and then test its performance. The sample provides a set of predefined commands that allow you to configure the radio in three modes:

  • Constant RX or TX carrier

  • Modulated TX carrier

  • RX or TX sweep


You can run the tests by connecting to the development kit through the serial port and sending shell commands. Zephyr’s Shell module is used to handle the commands. At any time during the tests, you can dynamically set the radio parameters, such as output power, bit rate, and channel. In sweep mode, you can set the time for which the radio scans each channel from 1 millisecond to 99 milliseconds, in steps of 1 millisecond. The sample also allows you to send a data pattern to another development kit.

The sample starts with enabling the high frequency crystal oscillator and configuring the shell. You can then start running commands to set up and control the radio. See User interface for a list of available commands.


For the IEEE 802.15.4 mode, the start channel and the end channel must be within the channel range of 11 to 26. Use the start_channel and end_channel commands to control this setting.


The sample supports the following development kits:

Hardware platforms


Board name

Build target

nRF5340 DK




nRF52840 DK




nRF52 DK




nRF21540 DK




You can use any one of the development kits listed above.


On nRF5340 DK, the sample is designed to run on the network core.

The sample also requires one of the following testing devices:


You can perform the radio test also using a spectrum analyzer. This method of testing is not covered by this documentation.

nRF21540 front-end module

You can add support for the nRF21540 front-end module (FEM) to the sample.

To add support for the nRF21540 FEM, build the sample for a board containing nRF21540 FEM like nrf21540dk_nrf52840 or create a devicetree overlay file describing how FEM is connected to nRF5 SoC in your device.


If you use the nRF21540 EK, append nrf21540_ek shield to your build command instructing build system to append the appropriate devicetree overlay file. If you use the nRF21540 DK, build your application for the nrf21540dk_nrf52840 board. The devicetree for the nRF21540 DK already contains the required FEM configuration, so you do not need to set an additional build option.

For example, to build the sample from the command line for an nRF5340 DK with an attached nRF21540 EK, invoke the following command within the sample directory: west build -b nrf5340dk_nrf5340_cpunet -- -DSHIELD=nrf21540_ek


The nRF5340 DK network core peripherals, like UART and SPI, share an ID and a base address. To configure the nRF21540 front-end module gain, write the gain value over the SPI. In samples, UART is used as a control interface or shell transport. To send the gain value UART is temporary disabled and restarted after the SPI transfer.

The nRF21540 transmitted power gain, antenna and an activation delay can be configured using the user interface User interface.

User interface

Main shell commands (in alphabetical order)





Cancel the sweep or the carrier.



Set the data rate.



End channel for the sweep (in MHz, as difference from 2400 MHz).



Set nRF21540 Front-End-Module parameters.



Output power set.


Print current delay, channel, and other parameters.


Print the received RX payload.



Start channel for the sweep or the channel for the constant carrier (in MHz, as difference from 2400 MHz).



Duty cycle in percent (two decimal digits, between 01 and 99).


Start RX.


Start the RX sweep.


Start the TX carrier.



Start the modulated TX carrier (continuous TX mode is used if no argument is provided).


Start the TX sweep.



Time on each channel in ms (between 1 and 99).



Toggle DC/DC converter state.



Set transmission pattern.

Building and running

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

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


On the nRF5340 DK board (PCA10095), the Radio test sample is a standalone network sample that does not require any counterpart application sample. However, you must still program the application core to boot up the network core. You can use any sample for this, for example nRF5340: Empty firmware for application core. The nRF5340: Empty firmware for application core is built and programmed automatically by default. If you want to program another sample for the application core, unset the CONFIG_NCS_SAMPLE_EMPTY_APP_CORE_CHILD_IMAGE option.


After programming the sample to your development kit, you can test it in one of two ways.


For the nRF5340 DK board (PCA10095), see Getting logging output for information about the COM terminals on which the logging output is available.

Testing with another development kit

  1. Connect both development kits to the computer using a USB cable. The kits are assigned a COM port (Windows) or ttyACM device (Linux), which is visible in the Device Manager.

  2. Connect to both kits with a terminal emulator (for example, PuTTY). See How to connect with PuTTY for the required settings.

  3. Run the following commands on one of the kits: #. Set the data rate with the data_rate command to ble_2Mbit. #. Set the transmission pattern with the transmit_pattern command to pattern_11110000. #. Set the radio channel with the start_channel command to 40.

  4. Repeat all steps for the second kit.

  5. On both kits, run the parameters_print command to confirm that the radio configuration is the same on both kits.

  6. Set one kit in the Modulated TX Carrier mode using the start_tx_modulated_carrier command.

  7. Set the other kit in the RX Carrier mode using the start_rx command.

  8. Print the received data with the print_rx command and confirm that they match the transmission pattern (0xF0).

Testing with RSSI Viewer

  1. Connect the kit to the computer using a USB cable. The kit is assigned a COM port (Windows) or ttyACM device (Linux), which is visible in the Device Manager.

  2. Connect to the kit with a terminal emulator (for example, PuTTY). See How to connect with PuTTY for the required settings.

  3. Set the start channel with the start_channel command to 20.

  4. Set the end channel with the end_channel command to 60.

  5. Set the time on channel with the time_on_channel command to 50ms.

  6. Set the kit in the TX sweep mode using the start_tx_sweep command.

  7. Start the RSSI Viewer application and select the kit to communicate with.

  8. On the application chart, observe the TX sweep in the form of a wave that starts at 2420 MHz frequency and ends with 2480MHz.


This sample uses the following nrfx dependencies:

  • nrfx/drivers/include/nrfx_timer.h

  • nrfx/hal/nrf_nvmc.h

  • nrfx/hal/nrf_power.h

  • nrfx/hal/nrf_radio.h

  • nrfx/hal/nrf_rng.h

In addition, it uses the following Zephyr libraries: