nrf52840 and sky66112-11 configuration


I am currently trying to use a sky66112-11 to get a range increase.

I had previously used a nrf21540DK to interface with the 21540 FEM using the built in MPSL support and was very successful.

Now I am using a custom board that uses the sky module as the FEM. (It is a Fanstel BT840X if that helps)

I have followed the docs here: under "Adding support for Skyworks front-end module" and added the following node to my device tree:

	nrf_radio_fem: skyFem {
		compatible = "skyworks,sky66112-11", "generic-fem-two-ctrl-pins";
		ctx-gpios = <&gpio0 17 GPIO_ACTIVE_HIGH>;
		crx-gpios = <&gpio0 19 GPIO_ACTIVE_HIGH>;
		cps-gpios = <&gpio0 6 GPIO_ACTIVE_HIGH>;
		chl-gpios = <&gpio0 8 GPIO_ACTIVE_HIGH>;
		rx-gain-db = < 11 >;
		tx-gain-db = < 22 >;

As far as I can tell MPSL is creating the file to turn on FEM, it is going into the two pin fem code path, and no errors are reported. Furthermore, the pins are correct according to Fanstel docs

However, I have seen no increase in RSSI on either the receive or transmit side over not adding the FEM node to the device tree. Additionally, there is no increase in amp draw seen through the Nordic Power Profiler Kit 2. Per the sky docs, we should see a 3-6ma increase from the LNA and upwards of a 100ma increase from the PA.

As far as I can tell I have followed the docs and all the right code seems to be being run, so I'm a bit lost on where to go next.

Thank you

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