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!

[Jackie Zamow]

I finally solved this issue in v1.9.1! The REAL steps to turn on FEM are as follows, or at least what worked for me:

1) Add the following node to boards/nrf5340dk_nrf5340_cupapp.overlay file AND child_image/hci_rpmsg.overlay:

/ {
nrf_radio_fem: name_of_fem_node {
compatible = "nordic,nrf21540-fem";
tx-en-gpios = <&gpio0 3 GPIO_ACTIVE_HIGH>;
rx-en-gpios = <&gpio0 5 GPIO_ACTIVE_HIGH>;
pdn-gpios = <&gpio0 7 GPIO_ACTIVE_HIGH>;
};
};

2) Add the following file to your project child_image\hci_rpmsg\boards\thingy53_nrf5340_cpunet.conf:

# Copyright (c) 2021 Nordic Semiconductor ASA
#
# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
#

CONFIG_RPMSG_SERVICE=y
CONFIG_RPMSG_SERVICE_MODE_REMOTE=y

CONFIG_HEAP_MEM_POOL_SIZE=8192

CONFIG_MAIN_STACK_SIZE=512
CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=512
CONFIG_BT=y
CONFIG_BT_HCI_RAW=y
CONFIG_BT_MAX_CONN=10
CONFIG_BT_CTLR_ASSERT_HANDLER=y
CONFIG_BT_HCI_RAW_RESERVE=1
CONFIG_BT_BUF_CMD_TX_COUNT=10

# Increase maximum data length of PDU supported in the Controller
CONFIG_BT_CTLR_DATA_LENGTH_MAX=251
CONFIG_BT_BUF_ACL_TX_SIZE=251
CONFIG_BT_BUF_ACL_RX_SIZE=502