Whats the purpose of the preprocessor definition ENABLE_FEM

[johnmartin117]

My setup: custom board using nRF52840, Segger Embedded Studio 3.52, nRF5_SDK_for_Thread_and_Zigbee_v4

I used a couple of your projects as a starting point for my code. Specifically:

zigbee_light_coordinator_pca10056

zigbee_cli_agent_router_pca10056

ble_zigbee_dynamic_light_switch_nus_pca10056_s140

In each of these projects the preprocessor definition ENABLE_FEM is defined (Options->Code->Preprocessor->Preprocessor Definitions). What does ENABLE_FEM do? My solution uses both Zigbee and BLE, can I remove ENABLE_FEM?

The reason I ask is because in looking through the source code, the file zb_nrf52_transciever.c sets 3 gpio pins if ENABLE_FEM is defined:

- Pin 19 for FEM_CONTROL_DEFAULT_LNA_PIN

- Pin 22 for FEM_CONTROL_DEFAULT_PA_PIN

- Pin 23 for FEM_CONTROL_DEFAULT_PDN_PIN

I'm using these 3 pins for another purpose and I just want to make sure I'm not stepping on anything.

Thanks,

John

[Patrick]

It is a define for the nRF21540 RF Range Extender. I'd guess its pretty safe for you to omit this define from your project, unless of course you're using the FEM.