Using LF RC oscillator for BLE application on NRF52840

Hello!

I am trying to use the LF RC oscillator on the NRF52840 in a BLE application, but I can’t connect to the device. I think that’s because the LF RC oscillator is never calibrated. I am testing on the BLE_GattServer example on the NRF52840-DK. I added the following configs to my mbed_app.json:

"config": {
    "lf_clock_rc_calib_timer_interval": {
        "value": 16,
        "macro_name": "MBED_CONF_NORDIC_NRF_LF_CLOCK_CALIB_TIMER_INTERVAL"
    },
    "lf_clock_rc_calib_mode_config": {
        "value": 2,
        "macro_name": "MBED_CONF_NORDIC_NRF_LF_CLOCK_CALIB_MODE_CONFIG"
    },
    "lf_clock_xtal_accuracy": {
        "value": "NRF_CLOCK_LF_XTAL_ACCURACY_500_PPM",
        "macro_name": "MBED_CONF_NORDIC_LF_CLOCK_XTAL_ACCURACY"
    }
},
"target_overrides": {
    "*": {
        ...
        "target.lf_clock_src": "NRF_LF_SRC_RC",
        ...
    }
}

I have those from around the internet. I found though, that most of these macro end up in some
SoftDevice code that is not used. MBED_CONF_NORDIC_LF_CLOCK_XTAL_ACCURACY isn’t even used at all (at least from what I found). How can I configure mbed to calibrate the LF RC oscillator regularly? Do I have to calibrate it “by hand” using the NRF SDK?