IEEE 802.15.4 Raw Mode + SKY66112 FEM not working in NCS 3.1.1 (worked in NCS 2.4)

RE: IEEE 802.15.4 Raw Mode + SKY66112 FEM not working in NCS 3.1.1 (worked in NCS 2.4)

Susheel Nuguru — Wed, 07 Jan 2026 10:30:18 GMT

That will be nice if you can come back with your finding or more questions here Carton, thanks for caring for the forum.

Carton_ — Wed, 07 Jan 2026 07:08:45 GMT

Thank you for your answer.

I was asking because this is a setup that worked perfectly with NCS 2.4.x. At no point did I have the feeling that it was not supposed to work.

As I do not have much time for this topic right now, I will stay with NCS 2.4.x. I was hoping for an easy and straightforward upgrade.

I will inform the forum if I find a workaround to make my FEM work with raw 802.15.4 if I can find more time to work on it in the future.

Susheel Nuguru — Tue, 06 Jan 2026 17:47:29 GMT

Hi Carton,

I do not see anywhere that IEEE 802.15.4 raw mode + Simple GPIO FEM as supported. FEM auto-control via MPSL is only listed for Thread, Zigbee, BLE controller, and multiprotocol. For other radio protocol implementations and applications that control the radio directly, you must use the MPSL FEM API yourself (which you most likely already know). See enabling fem support
I do not see any documented breaking change in sources or readme files. But I doubt that we could have missed to document any breaking changes of an important module of MPSL, so my best educated guess is that there are no breaking changes.
Additional configuration for raw mode: beyond CONFIG_MPSL, CONFIG_MPSL_FEM, and the FEM devicetree node you must integrate FEM control via the MPSL FEM API in your app/driver, because raw mode is direct radio control.