I'm working on a project with a custom board which is based on a Laird Connectivity BL654PA, which has a nRF52840 and a Skyworks sky66112-11, which acts as a power amplifier or low noise amplifier for Bluetooth. This project is running on the nRFConnect SDK version 2.3.0, and we're using a custom deviceTree file to support our custom board as well.
I have a massive issue with the strength of the Bluetooth signal - I'm unable to even see any Bluetooth signals from the device from more than a few feet away, with RSSI values in the -90s when I can see signals. When the same code is ran on the custom board using the nrf21540 dk nrf52840 build configuration instead of our custom one, the range issue is immediately resolved. Unfortunately, this is not an option for a solution because using the 21540 build config does break some things like LEDs due to inherent differences in things like pinouts, and I'd like to get this running with the custom board config.
These issues suggest that I'm not actually interfacing with the FEM correctly. I've followed all the steps outlined by Nordic (see https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.3.0/nrf/app_dev/working_with_fem/index.html#ug-radio-fem-skyworks)
I've also done the fixes outlined in the post linked here to enable two pin control support for the FEM RE: Skyworks FEM control with 802.15.4 with NCS/Zephyr 2.0.0, with the only difference being that the ctx pin is set to pin 4 and the crx pin is set to pin 2 in accordance with the documentation given by Laird (see link: https://www.lairdconnect.com/documentation/application-note-nordic-sdk-based-application-development-bl654pa ). This documentation from Laird is based on a very outdated SDK Version, however, so I don't really trust the rest of the code mentioned in there to work at all.
None of these steps have given me any degree of success in fixing this issue. What else could possibly be wrong? Is there any sort of special configuration or initialization that needs to be done to work with the Skyworks FEM that isn't listed in either of the Nordic documents? Do I need to add any additional code related to Bluetooth and the FEM that I wouldn't have needed when I originally developed this code on a 21540dk? Are there any examples out there using a Skyworks FEM with a 52840 that I can look at?
