zigbee + fem (nRF21540) on nrf54L05

RE: zigbee + fem (nRF21540) on nrf54L05

Kenneth — Tue, 03 Feb 2026 10:54:06 GMT

Hello,

Personally I would recommend the nRF54L series for everything moving forward, there is a lot going on for that series. I do know there are discussions ongoing for zigbee support for the nRF54L series, but I can't comment on timeline, so please reach out to your nordic sales contact and they may hopefully provide you with a timeline.

Hope that helps,
Kenneth

RE: zigbee + fem (nRF21540) on nrf54L05

jaydev_borkar — Thu, 29 Jan 2026 12:42:06 GMT

Kenneth :

Thank you for the clarification.

Based on this, we understand that FEM support for nRF54L-series is only available starting from NCS v3.1.0, while the current Zigbee add-on is limited to NCS v2.9.2.

Could you please help clarify:

Is there any roadmap or timeline for Zigbee add-on support on NCS v3.x for nRF54L-series?
Is there any supported workaround to use FEM with Zigbee on nRF54L-series today, or is this strictly unsupported?
For Zigbee + FEM use cases at present, would you recommend using an nRF52 or nRF53 series device instead of nRF54L?

This will help us decide the next steps in our design.

Final Question : What is the recommended Zigbee Router configuration for nRF54L-series in NCS 2.9.2 to maximize range and routing reliability?

RE: zigbee + fem (nRF21540) on nrf54L05

Kenneth — Thu, 29 Jan 2026 07:18:03 GMT

Sorry for the late reply, but seems that there is no fem support for nRF54L-series for zigbee.

Reason is because latest zigbee add-on is for ncs v2.9.2, while fem support did not occur until ncs v3.1.0. See:
"Added support for the nRF21540 Front-End Module in GPIO/SPI mode on the nRF54L Series SoCs. (KRKNWK-15977)"
https://docs.nordicsemi.com/bundle/ncs-latest/page/nrfxlib/mpsl/CHANGELOG.html#nrf_connect_sdk_v310

Kenneth

RE: zigbee + fem (nRF21540) on nrf54L05

jaydev_borkar — Thu, 22 Jan 2026 12:19:14 GMT

Hey Kenneth ,

We are using the same nRF Connect SDK version v2.9.2 (R23) and have based our work on the Shell example from this SDK.

The hardware in use is an nRF54L15 DK. We do not have a dedicated FEM (nRF21540) DK. The zephyr.dts and .config files used for this experiment are attached for reference.

Note: The same FEM configuration works correctly with the BLE Observer example with v3.0.0 of SDK, but fails when applied to the Zigbee Shell example(v2.9.2) on the same board.

devzone.nordicsemi.com/.../06025.zephyr.dts devzone.nordicsemi.com/.../4667_2E00_config

RE: zigbee + fem (nRF21540) on nrf54L05

Kenneth — Thu, 22 Jan 2026 11:58:58 GMT

Hi,

Asbjørn is away, so I can try to take a look at this question.

Are you using nRF Connect SDK v2.9.2, or are you using something older? Would be good if you can try v2.9.2 if you haven't already.
https://docs.nordicsemi.com/bundle/addon-zigbee-r23-latest/page/index.html
https://docs.nordicsemi.com/bundle/addon-zigbee-r23-latest/page/release-notes.html

Also do you have a DK for comparison (or at least you can compile and compare .config and zephyr.dts files if you are doing your custom board)?

Kenneth

RE: zigbee + fem (nRF21540) on nrf54L05

jaydev_borkar — Mon, 19 Jan 2026 12:55:07 GMT

runsiv Any update on this ?

RE: zigbee + fem (nRF21540) on nrf54L05

jaydev_borkar — Wed, 14 Jan 2026 05:22:19 GMT

Hi runsiv ,

Thank you for your response !

We had used the following portion in prj.conf and overlay description for the observer code (BLE) to work with FEM. It had worked fine for us. When we are using the same config of prj.conf and overlay descriptor for zigbee shell example its throwing error.

##########################

prj.conf

##########################

# #### Enable FEM supporty#####

# Enable Nordic Multiprotocol Service Layer (needed for FEM)

CONFIG_MPSL=y

# Enable Front-End Module (FEM) support

CONFIG_MPSL_FEM=y

CONFIG_MPSL_FEM_NRF21540_GPIO=y

# Enable runtime PA gain control (toggle between 10 dB and 20 dB)

#CONFIG_MPSL_FEM_NRF21540_RUNTIME_PA_GAIN_CONTROL=y

# TX gain settings

CONFIG_MPSL_FEM_NRF21540_TX_GAIN_DB=20

CONFIG_MPSL_FEM_NRF21540_TX_GAIN_DB_POUTA=20

CONFIG_MPSL_FEM_NRF21540_TX_GAIN_DB_POUTB=10

# RX gain setting

CONFIG_MPSL_FEM_NRF21540_RX_GAIN_DB=13

# Enable FEM debug logging

CONFIG_MPSL_FEM_LOG_LEVEL_DBG=y

##########################

overlay

##########################

/ {

nrf_radio_fem: name_of_fem_node {

compatible = "nordic,nrf21540-fem";

tx-en-gpios = <&gpio1 10 GPIO_ACTIVE_HIGH>;

rx-en-gpios = <&gpio1 11 GPIO_ACTIVE_HIGH>;

pdn-gpios = <&gpio1 12 GPIO_ACTIVE_HIGH>;

ant-sel-gpios = <&gpio1 13 GPIO_ACTIVE_LOW>; // use LOW -ant 1 ,HIGH -ant 2

};

&dppic10 {

status = "okay";

};

&ppib11 {

status = "okay";

};

&ppib21 {

status = "okay";

};

&dppic20 {

status = "okay";

};

&ppib22 {

status = "okay";

};

&ppib30 {

status = "okay";

};

&dppic30 {

status = "okay";

};

-----------------------------------------------------------------------------------------------------------------------------------------------

We also used your suggestion of prj.conf of adding
CONFIG_MPSL=y
CONFIG_MPSL_FEM=y

and same overlay file as mentioned above. It throws the same error in the shell example of zigbee.

-----------------------------------------------------------------------------------------------------------------------------------------------

The error logs are as follows:

[00:02:00.662,048] <err> os: r0/a1: 0x00000003 r1/a2: 0x00000000 r2/a3: 0x00000001
[00:02:00.662,057] <err> os: r3/a4: 0x00000003 r12/ip: 0x00000000 r14/lr: 0x0000674d
[00:02:00.662,064] <err> os: xpsr: 0x09100000
[00:02:00.662,074] <err> os: s[ 0]: 0x00000000 s[ 1]: 0x0001a39d s[ 2]: 0x500da000 s[ 3]: 0x00001e81
[00:02:00.662,084] <err> os: s[ 4]: 0x00000078 s[ 5]: 0x00303231 s[ 6]: 0x00000003 s[ 7]: 0x0bad0000
[00:02:00.662,094] <err> os: s[ 8]: 0x0000000d s[ 9]: 0x00002b29 s[10]: 0x0bad0000 s[11]: 0x0001a5ff
[00:02:00.662,105] <err> os: s[12]: 0x050607ff s[13]: 0x500da000 s[14]: 0xffffff00 s[15]: 0x500da000
[00:02:00.662,111] <err> os: fpscr: 0xffffff00
[00:02:00.662,118] <err> os: Faulting instruction address (r15/pc): 0x0001a3e0
[00:02:00.662,137] <err> os: >>> ZEPHYR FATAL ERROR 3: Kernel oops on CPU 0
[00:02:00.662,155] <err> os: Current thread: 0x20004578 (main)
[00:02:00.800,039] <err> mpsl_init: MPSL ASSERT: 120, 29
[00:02:00.800,049] <err> os: ***** HARD FAULT *****
[00:02:00.800,056] <err> os: Fault escalation (see below)
[00:02:00.800,062] <err> os: ARCH_EXCEPT with reason 3

RE: zigbee + fem (nRF21540) on nrf54L05

runsiv — Tue, 13 Jan 2026 12:20:52 GMT

As I understand it if you are using MPSL it should take care of the FEM support with Zigbee for you.

It should be enough to just add the following and the description of the fem in the overlay

CONFIG_MPSL=y
CONFIG_MPSL_FEM=y

Regards

Runar