Unable to recover a nrf5340 MCU after first flash on a custom board using nrf5340 DK

RE: Unable to recover a nrf5340 MCU after first flash on a custom board using nrf5340 DK

PaKa — Thu, 30 Oct 2025 06:54:48 GMT

If you meant to say you shorted DECD to 3.3V then you very likely have damaged parts of the chip as that node should not see those voltage levels.

RE: Unable to recover a nrf5340 MCU after first flash on a custom board using nrf5340 DK

LL01 — Wed, 29 Oct 2025 09:58:44 GMT

Thank you for documenting this. During my development process, I also encountered MCU startup issues caused by setting different power modes. Your documentation provided valuable insights that helped me resolve my problem. Regarding the MCU reset, I managed to reprogram the previously misconfigured board by shorting DCED to 3.3V using tweezers for reconfiguration. I'm adding this as a supplementary note here. Thank you again for your documentation!

RE: Unable to recover a nrf5340 MCU after first flash on a custom board using nrf5340 DK

Lumisoft — Wed, 07 Feb 2024 16:24:53 GMT

Hi Håkon,

I was not yet able to restore the previous boards with the recover loop script, but I confirm by disabling DCDC the issue is solved and nrf53 is not constantly rebooting.

I used these configs for that:

CONFIG_BOARD_ENABLE_DCDC_NET=n
CONFIG_BOARD_ENABLE_DCDC_HV=n
CONFIG_BOARD_ENABLE_DCDC_APP=n

Thank you!

Kind regards,

Michael

RE: Unable to recover a nrf5340 MCU after first flash on a custom board using nrf5340 DK

Håkon Alseth — Wed, 07 Feb 2024 15:41:25 GMT

Hi Michael,

Thanks for sharing the schematic.

It shows that there is no DCDC components in-place. If your firmware is configured without explicitly disabling DCDC, it will boot up, set DCDCEN register(s), and reset itself due to a power-on-reset.

The first recommendation is to update your nrf-command line tools installation to the newest:

https://www.nordicsemi.com/Products/Development-tools/nrf-command-line-tools/download

After that, you can try to run a recover loop script, to see if you are then able to recover the device:

RE: nRF52832 not connected anymore after first trying to debug (Keil)

Switch out the "-f nrf52" to "-f nrf53".

You can also try to vary the SWD speed, via adding "-c 125" for instance. This will switch the SWD speed to 125 kHz.

Kind regards,

Håkon

RE: Unable to recover a nrf5340 MCU after first flash on a custom board using nrf5340 DK

Lumisoft — Wed, 07 Feb 2024 12:43:31 GMT

Hi Håkon,

Yes, 32k is included, here is the schematic around module:

We tried to follow manufacturer recommendations. You think I can restore/clear MCU?

I also tried to recover network coprocessor, but facing almost the same:
devzone.nordicsemi.com/.../528725.log.log

Thank you!

Kind regards,

Michael

RE: Unable to recover a nrf5340 MCU after first flash on a custom board using nrf5340 DK

Håkon Alseth — Wed, 07 Feb 2024 12:24:23 GMT

Hi,

[quote user=""]I was trying to flash a custom board using a nrf5340 module (Raytac MDBT53-1M) [/quote]

How is the schematic around this module? Do you include a 32k xtal and/or DCDC-components?

If not, you will have to manually specify both the 32k source + disable DCDC.

In your prj.conf:

# disable DCDC
CONFIG_BOARD_ENABLE_DCDC_APP=n
CONFIG_BOARD_ENABLE_DCDC_NET=n
CONFIG_BOARD_ENABLE_DCDC_HV=n

# Use internal 32k RC oscillator
CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y

If you enable BT, you need to create file/folder and set this in child_images/hci_rpmsg.conf:

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y

[quote user=""]I attached the log of the command:
nrfjprog --recover --family nRF53 --log[/quote]

Could you first try to recover the net core, then the app core?

nrfjprog --recover -f nrf53 --coprocessor cp_network

Kind regards,

Håkon