nRF Connect SDK Intermediate, Lesson 9, Exercise 4, problems with nrF53

[John-Eric Kamps]

Hi

SDK 3.4.1

Custom Board but with working USB-Interface from App

https://academy.nordicsemi.com/courses/nrf-connect-sdk-intermediate/lessons/lesson-9-bootloaders-and-dfu-fota/topic/exercise-4-dfu-over-usb/

If I configure it like described, I will get no USB-CDC device. The Serial port is present.

From my current understanding of mcuboot it is wrong to setup

STEP 1.1 - Configure serial recovery to use CDC_ACM, which by default uses the USB
CONFIG_MCUBOOT_SERIAL=y
CONFIG_BOOT_SERIAL_UART=y

It should be

STEP 1.1 - Configure serial recovery to use CDC_ACM, which by default uses the USB

CONFIG_MCUBOOT_SERIAL=y

CONFIG_BOOT_SERIAL_UART=n

CONFIG_BOOT_SERIAL_CDC_ACM=y

But with that I got an error:
2026-10-30T09:39:03.377Z C:/ncs/toolchains/4f5b6ad6dd/opt/zephyr-sdk/gnu/arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/14.3.0/../../../../arm-zephyr-eabi/bin/ld.bfd.exe: zephyr/subsys/usb/device_next/libsubsys__usb__device_next.a(usbd_cdc_acm.c.obj):C:/ncs/v3.4.1/zephyr/subsys/usb/device_next/class/usbd_cdc_acm.c:1386: multiple definition of `__device_dts_ord_190'; zephyr/libzephyr.a(cdc_acm.c.obj):C:/ncs/v3.4.1/zephyr/subsys/usb/device/class/cdc_acm.c:1229: first defined here

Is the usb-next driver not final in mcuboot for nrf53?

Best regards 

John

[AHaug]

Hi John,

That is correct, usb next is not an option for the nrf5340. It will alsways select the legacy USB device stack. The kconfig to enable USB next selects only Next for nRF54 series devices

config BOOT_SERIAL_CDC_ACM
	bool "CDC ACM"
	select USB_DEVICE_STACK if !(SOC_NRF54LM20A || SOC_NRF54LM20B)
	select USB_DEVICE_STACK_NEXT if (SOC_NRF54LM20A || SOC_NRF54LM20B)

We'll look into the exercise and double check if and what is wrong/not working for the non nRF54LM20 devices.

Kind regards,
Andreas

[AHaug]

Hi again,

The author agrees that a fix is required. They will make an update to the course to either highlight the different requirement for the SoCs and/or patch the issue. Resolution is TBD and depends on what is supported in the SDK tag.

Reassigning the case to them and leaving it as open.

Thank you for reporting this,

Kind regards,
Andreas