Front End Module control with nRF Connect (1.7.0)

[Jackie Zamow]

Hi,

I'm trying to enable PA/LNA control with a nRF5340 using the nRF Connect SDK v1.7.0. This version was the first to introduce FEM control, as described here: http://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/ug_radio_fem.html

I'm wondering whether the steps listed in the linked documentation are the only steps I need to take to enable this feature. Is there an initialization function call I need to make in my firmware to "turn on" the feature? Or a config flag I need to add to my .config file? The article above only mentions modifications to the devicetree file.

Thanks for the help!

[Kenneth]

I'm wondering whether the steps listed in the linked documentation are the only steps I need to take to enable this feature.

These are all the steps required yes, also see how to do this can be done for a specific BLE sample project (e.g. peripheral UART example):
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/samples/bluetooth/peripheral_uart/README.html#fem-support 

[Jackie Zamow]

So as far as I can tell, there are 4 main steps:

1) Add MPSL support by configuring the interrupts listed here: http://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrfxlib/mpsl/doc/mpsl.html#mpsl-lib

2) Enable MPSL with a config flag in the application core (CONFIG_MPSL = y)

3) Add a node to the application device tree, shown here: http://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/ug_radio_fem.html

4) Add that same node to the child device tree

Right now, I'm struggling with #1. How am I supposed to configure the interrupts to be priority 0? Via a Kconfig flag, or a function call in the application?

[Jackie Zamow]

Hi, I'm still working on this issue, but now in SDK version 1.8.0. Going back to the link you sent, the option that makes the most sense for our application is "Manually create a devicetree overlay file that describes how FEM is connected to the nRF5 SoC in your device." This is because we are not using the specific nRF21540 FEM, we just want to use the 2 wire FEM interface.

What is necessary to manually create the overlay file? Are there any Kconfig flags that I need to mention in my prj.config file to support the new node in my overlay file? Is the child image overlay file supposed to have a new node as well?