Arduino Compiler {build.flags.usb} directive

Hi,
I am new at this.
I purchased a SparkFun Pro nRF52840 Mini and am trying to compile an example (LED blink).
As a matter of fact, I am having the same issue when I try to compile a new (empty) sketch.
I am getting the following error:
arm-none-eabi-g++: error: {build.flags.usb}: No such file or directory.
Looking at the compile Output, I see the compiler execution line. Everything is consistent with the platform.txt compilation flags except that when the sketch is being compiled, it looks like additional flags are added after the last -MMD specified in the platform.txt file.
a -{build.flags.usb}.
I am using Arduino IDE 2.1.0
Any idea where this is coming from and how to fix it?
Thanks,
Fred

and what boards package you use and what board do you select in the Tools menu?

Hi,
The selected board is the SparkFun Pro nRF52840 Mini.
As far as board package, I believe I am using the Arduino nRF52 Boards package.
Interestingly enough, when the libraries are being compiled, that flag is not referenced:
"C:\Users\frede\AppData\Local\Arduino15\packages\arduino\tools\arm-none-eabi-gcc\4.8.3-2014q1/bin/arm-none-eabi-g++" -DNRF5 -DNRF52 -DS132 -DSOFTDEVICE_PRESENT -DBLE_STACK_SUPPORT_REQD -DCONFIG_GPIO_AS_PINRESET -DARDUINO=10607 -DARDUINO_NRF52840_FEATHER -DARDUINO_ARCH_NRF52 -DARDUINO_PRIMO -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -mthumb -c -g -Os -w -ffunction-sections -fexceptions -fdata-sections -fno-rtti -fno-builtin -w -x c++ -E -CC -DNRF52840_XXAA "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\tools\CMSIS\4.5.0/CMSIS/Include" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/device" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/hal" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/clock" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/common" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/delay" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/uart" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/rng" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/util" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/timer" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/trace" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/scheduler" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/uart" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/softuart" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/fifo" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/ecc" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/ac_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/ep_oob_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/hs_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/le_oob_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/generic/message" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/generic/record" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/launchapp" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/parser/message" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/parser/record" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/text" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/uri" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_lib" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_lib/hal_t2t" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_parser" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_lib" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/common" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/softdevice/s132/headers" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/softdevice/common/softdevice_handler" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/toolchain" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/toolchain/gcc" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/pstorage" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/pstorage/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/fstorage" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/fstorage/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/experimental_section_vars" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/device_manager" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/device_manager/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/ble_services/ble_dfu" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/bootloader_dfu" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/ble_advertising" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2\cores\nRF5" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2\variants\sparkfun_nrf52840_mini" "-Ic:\Users\frede\OneDrive\Documents\Arduino\libraries\arduino" "-Ic:\Users\frede\OneDrive\Documents\Arduino\libraries\BLEPeripheral\src" "c:\Users\frede\OneDrive\Documents\Arduino\libraries\arduino\DFUService.cpp" -c -o nul

And when the compiler generates the function prorotypes:
C:\Users\frede\AppData\Local\Arduino15\packages\arduino\tools\arm-none-eabi-gcc\4.8.3-2014q1/bin/arm-none-eabi-g++" -DNRF5 -DNRF52 -DS132 -DSOFTDEVICE_PRESENT -DBLE_STACK_SUPPORT_REQD -DCONFIG_GPIO_AS_PINRESET -DARDUINO=10607 -DARDUINO_NRF52840_FEATHER -DARDUINO_ARCH_NRF52 -DARDUINO_PRIMO -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -mthumb -c -g -Os -w -ffunction-sections -fexceptions -fdata-sections -fno-rtti -fno-builtin -w -x c++ -E -CC -DNRF52840_XXAA "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\tools\CMSIS\4.5.0/CMSIS/Include" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/device" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/hal" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/clock" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/common" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/delay" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/uart" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/rng" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/util" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/timer" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/trace" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/scheduler" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/uart" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/softuart" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/fifo" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/ecc" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/ac_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/ep_oob_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/hs_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/le_oob_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/generic/message" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/generic/record" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/launchapp" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/parser/message" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/parser/record" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/text" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/uri" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_lib" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_lib/hal_t2t" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_parser" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_lib" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/common" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/softdevice/s132/headers" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/softdevice/common/softdevice_handler" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/toolchain" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/toolchain/gcc" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/pstorage" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/pstorage/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/fstorage" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/fstorage/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/experimental_section_vars" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/device_manager" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/device_manager/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/ble_services/ble_dfu" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/bootloader_dfu" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/ble_advertising" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2\cores\nRF5" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2\variants\sparkfun_nrf52840_mini" "-Ic:\Users\frede\OneDrive\Documents\Arduino\libraries\arduino" "-Ic:\Users\frede\OneDrive\Documents\Arduino\libraries\BLEPeripheral\src" "C:\Users\frede\AppData\Local\Temp\arduino\sketches\4C3F718C8BA186F52D39423B6EE7D80E\sketch\led.ino.cpp" -c -o "C:\Users\frede\AppData\Local\Temp\arduino\sketches\4C3F718C8BA186F52D39423B6EE7D80E\preproc\ctags_target_for_gcc_minus_e.cpp"
But when it gets to the sketch, I end up with an extra {build.flags.usb} in the compiler line:
Compiling sketch...
"C:\Users\frede\AppData\Local\Arduino15\packages\arduino\tools\arm-none-eabi-gcc\4.8.3-2014q1/bin/arm-none-eabi-g++" -DNRF5 -DNRF52 -DS132 -DSOFTDEVICE_PRESENT -DBLE_STACK_SUPPORT_REQD -DCONFIG_GPIO_AS_PINRESET -DARDUINO=10607 -DARDUINO_NRF52840_FEATHER -DARDUINO_ARCH_NRF52 -DARDUINO_PRIMO -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -mthumb -c -g -Os -w -ffunction-sections -fexceptions -fdata-sections -fno-rtti -fno-builtin -MMD -DNRF52840_XXAA {build.flags.usb} "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\tools\CMSIS\4.5.0/CMSIS/Include" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/device" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/hal" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/clock" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/common" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/delay" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/uart" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/rng" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/util" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/timer" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/trace" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/scheduler" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/uart" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/softuart" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/fifo" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/ecc" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/ac_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/ep_oob_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/hs_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/le_oob_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/generic/message" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/generic/record" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/launchapp" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/parser/message" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/parser/record" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/text" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/uri" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_lib" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_lib/hal_t2t" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_parser" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_lib" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/common" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/softdevice/s132/headers" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/softdevice/common/softdevice_handler" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/toolchain" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/toolchain/gcc" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/pstorage" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/pstorage/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/fstorage" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/fstorage/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/experimental_section_vars" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/device_manager" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/device_manager/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/ble_services/ble_dfu" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/bootloader_dfu" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/ble_advertising" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2\cores\nRF5" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2\variants\sparkfun_nrf52840_mini" "-Ic:\Users\frede\OneDrive\Documents\Arduino\libraries\arduino" "-Ic:\Users\frede\OneDrive\Documents\Arduino\libraries\BLEPeripheral\src" "C:\Users\frede\AppData\Local\Temp\arduino\sketches\4C3F718C8BA186F52D39423B6EE7D80E\sketch\led.ino.cpp" -c -o "C:\Users\frede\AppData\Local\Temp\arduino\sketches\4C3F718C8BA186F52D39423B6EE7D80E\sketch\led.ino.cpp.o"
Thanks,
Fred

Hi,
I have selected the SparkFun Pro nRF52840 Mini after updating the boards.txt file.
As far as package, I believe I am using the Arduino nRF52 boards package.
The additional {build.flags.usb} only appears at the "Compiling sketch..." stage but not at the libraries compilation or "Generating function prototypes..." stage.
Thanks,
Fred

but the Sparkfun instructions say to install the Adafruit nRF52 boards package

I followed the instructions and ran into a mess and had to manually install all sorts of Libraries to get to this point.
I originally used the github URL referenced in the documentation (arduino-board-index/package_adafruit_index.json at gh-pages · adafruit/arduino-board-index · GitHub) and the only nRF52 board package I could find was the Arduino nRF52 Boards which by the way, supports SparkFun Pro nRF52840 Mini. I currently have the 1.2.0 version installed.

you copied the Sparkfun boards.txt into Arduino nRF52 boards package so you have the board in Tools menu. but that boards.txt is not compatible with the Arduino nRF52 b.p.

How do I fix this?
I used the instructions and used the provided github URL for the board package and modified the board.txt as specified.

*Edit
Talking about the board.txt file, I found the extra directive in that file:
sparkfunnrf52840mini.build.extra_flags=-DNRF52840_XXAA {build.flags.usb}

I tried to update the board.txt with the one provided in the Adafruit_nRF52 package but I am getting the same error.

try to uninstall the Arduino nRF52 boards package so it is not in the way of using the Adafruit nRF52 boards package

https://learn.sparkfun.com/tutorials/nrf52840-development-with-arduino-and-circuitpython

Thanks,
I will give it a try.
The link is what I used.
Regards,
Fred

Ok so I totally uninstalled Arduino, deleted the directories and cleaned up the registry.
I then proceeded to a clean re-install following the instructions to the letter.
First compilation on the Sparkfun Pro nRF52840 Mini gives me this error which is the kind of things I had to deal with during the first installation:
Detecting libraries used...
"C:\Users\frede\AppData\Local\Arduino15\packages\arduino\tools\arm-none-eabi-gcc\4.8.3-2014q1/bin/arm-none-eabi-g++" -DNRF5 -DNRF52 -DS132 -DSOFTDEVICE_PRESENT -DBLE_STACK_SUPPORT_REQD -DCONFIG_GPIO_AS_PINRESET -DARDUINO=10607 -DARDUINO_NRF52840_FEATHER -DARDUINO_ARCH_NRF52 -DARDUINO_PRIMO -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -mthumb -c -g -Os -w -ffunction-sections -fdata-sections -fno-rtti -fno-exceptions -fno-builtin -w -x c++ -E -CC -DNRF52840_XXAA "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\tools\CMSIS\4.5.0/CMSIS/Include" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/device" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/hal" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/clock" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/common" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/delay" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/uart" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/rng" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/util" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/timer" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/trace" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/scheduler" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/uart" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/softuart" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/fifo" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/ecc" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/ac_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/ep_oob_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/hs_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover/le_oob_rec" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/connection_handover" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/generic/message" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/generic/record" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/launchapp" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/parser/message" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/parser/record" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/text" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/ndef/uri" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_lib" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_lib/hal_t2t" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_parser" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/nfc/t2t_lib" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/common" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/softdevice/s132/headers" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/softdevice/common/softdevice_handler" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/toolchain" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/toolchain/gcc" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/pstorage" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/drivers_nrf/pstorage/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/fstorage" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/fstorage/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/experimental_section_vars" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/device_manager" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/device_manager/config" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/ble_services/ble_dfu" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/libraries/bootloader_dfu" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2/cores/arduino/components/ble/ble_advertising" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2\cores\nRF5" "-IC:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2\variants\sparkfun_nrf52840_mini" "C:\Users\frede\AppData\Local\Temp\arduino\sketches\48E9942082BD82A3AC00FCD3520EA5F4\sketch\sketch_jun29a.ino.cpp" -c -o nul
C:\Users\frede\AppData\Local\Temp\arduino\sketches\48E9942082BD82A3AC00FCD3520EA5F4\sketch\sketch_jun29a.ino.cpp:1:21: fatal error: Arduino.h: No such file or directory
#include <Arduino.h>
^
compilation terminated.

Also, Arduino won't let me save my preferences (SketchBook Location).
Thanks,
Fred

you didn't delete the boards package. remove it in Boards Manager

Here is what I am getting:
Platform 'arduino:nrf52' not found: platform not installed

Compilation error: Platform 'arduino:nrf52' not found: platform not installed
Which is not surprising as there are no board package installed.
Fred

it is still there and in every line of your compilation:
C:\Users\frede\AppData\Local\Arduino15\packages\arduino\hardware\nrf52\1.0.2

Please see my last message: I removed everything and now I get what I sent in my last message:
Platform 'arduino:nrf52' not found: platform not installed

Compilation error: Platform 'arduino:nrf52' not found: platform not installed

If I am not supposed to use the nrf52 package what am I supposed to use?
I followed the instructions and using the github url does not give me the option for the Adafruit nRF52 board package but instead the Arduino nRF52 board package.

Update:
Tried brand new installations with versions 2.1, 1.8 and 1.6 and the problem seems to be with the package URL.
I keep getting errors trying to download the board package. I followed the instructions to the T for all three versions and can't get the Adafruit nRF52 package downloaded. It never ends up showing up in the list of board packages.
Any help would be appreciated.
Here is the output in Version 1.6.12:
Error downloading http://downloads.arduino.cc/packages/package_index.json
java.lang.RuntimeException: java.lang.Exception: Error downloading http://downloads.arduino.cc/packages/package_index.json
at cc.arduino.contributions.packages.ui.ContributionManagerUI.lambda$onUpdatePressed$0(ContributionManagerUI.java:151)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.Exception: Error downloading http://downloads.arduino.cc/packages/package_index.json
at cc.arduino.contributions.DownloadableContributionsDownloader.download(DownloadableContributionsDownloader.java:113)
at cc.arduino.contributions.packages.ContributionInstaller.download(ContributionInstaller.java:334)
at cc.arduino.contributions.packages.ContributionInstaller.downloadIndexAndSignature(ContributionInstaller.java:309)
at cc.arduino.contributions.packages.ContributionInstaller.updateIndex(ContributionInstaller.java:287)
at cc.arduino.contributions.packages.ui.ContributionManagerUI.lambda$onUpdatePressed$0(ContributionManagerUI.java:147)
... 1 more
Caused by: java.net.UnknownHostException: downloads.arduino.cc
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at sun.net.NetworkClient.doConnect(NetworkClient.java:175)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:432)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:527)
at sun.net.www.http.HttpClient.(HttpClient.java:211)
at sun.net.www.http.HttpClient.New(HttpClient.java:308)
at sun.net.www.http.HttpClient.New(HttpClient.java:326)
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1169)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1148)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:999)
at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:933)
at cc.arduino.utils.network.FileDownloader.downloadFile(FileDownloader.java:170)
at cc.arduino.utils.network.FileDownloader.download(FileDownloader.java:128)
at cc.arduino.contributions.DownloadableContributionsDownloader.download(DownloadableContributionsDownloader.java:111)
... 5 more
Skipping contributed index file C:\Users\frede\AppData\Local\Arduino15\package_adafruit_index.json, parsing error occured:
com.fasterxml.jackson.core.JsonParseException: Unexpected character ('<' (code 60)): expected a valid value (number, String, array, object, 'true', 'false' or 'null')
at [Source: java.io.FileInputStream@198121e; line: 8, column: 2]
Skipping contributed index file C:\Users\frede\AppData\Local\Arduino15\package_adafruit_index.json, parsing error occured:
com.fasterxml.jackson.core.JsonParseException: Unexpected character ('<' (code 60)): expected a valid value (number, String, array, object, 'true', 'false' or 'null')
at [Source: java.io.FileInputStream@125a5d4; line: 8, column: 2]
Skipping contributed index file C:\Users\frede\AppData\Local\Arduino15\package_adafruit_index.json, parsing error occured:
com.fasterxml.jackson.core.JsonParseException: Unexpected character ('<' (code 60)): expected a valid value (number, String, array, object, 'true', 'false' or 'null')
at [Source: java.io.FileInputStream@d967a5; line: 8, column: 2]

the instructions say you should install and patch the A D A F R U I T nRF52 package, not ARDUINO

Yes, I get that and I have been using the URL provided ( arduino-board-index/package_adafruit_index.json at gh-pages · adafruit/arduino-board-index · GitHub) but it does not work.
See the errors I documented above when Arduino tries to download the package.
Is there a different URL to use or a different way to install the board manager using a zip file maybe?

did you install the package in Boards Manager after adding the URL in Preferences?

As stated, the package as specified in the instructions does not download.
I did some digging and the correct gitURL for the Adafruit nRF52 package is:
https://adafruit.github.io/arduino-board-index/package_adafruit_index.json.
I successfully downloaded the package and installed it.
The board to select is the "Adafruit Feather nRF52840 Express". I cut and paste a sample code, compiled it, uploaded it and it worked.
I am good to go.