Unlocking of NRF53 which was locked after flashing the code once

[Palaniappan]

Hello team,

We use the module MDBT53-1M based on nRF5340 and there are no dc-dc components mounted in our hardware. Using nRF Programmer, we could flash nRF5340 for the first time. After that the device is not getting detected by the programmer and our board is unusable.

As suggested in the link, https://blog.mbedded.ninja/programming/microcontrollers/nordic/nrf53/unbricking-a-nrf53-due-to-dcdc-config/

we had applied external voltages to dc-dc pins 1.05V to DECR and 1.25V to DECD pins of nRF5340

We have included the below commands in proj.conf file also.

# Disabled all three internal SMPSs.

CONFIG_BOARD_ENABLE_DCDC_APP=n

CONFIG_BOARD_ENABLE_DCDC_NET=n

CONFIG_BOARD_ENABLE_DCDC_HV=n

when we tried with this, we could recover once. But it is not recovering every time.

Is there a way to unlock the device.

Thanks & Regards

Palaniappan 

Silicon Technologies

[Bendik Heiskel]

Hi Palaniappan,

 

Which version of the nRF Connect SDK are you using?

 

The way to configure the regulators have changed in v2.8.0, the Kconfig option are no longer used.

There is now devicetree nodes for configuring the regulators, to disable all the DCDC regulators you need a overlay file with:

&vregmain {
    regulator-initial-mode = <NRF5X_REG_MODE_LDO>;
};
&vregradio {
    regulator-initial-mode = <NRF5X_REG_MODE_LDO>;
};
&vregh {
    status = "disabled";
};                     

 

Best regards,

Bendik

[Palaniappan]

Dear Bendik

Thanks for your reply and suggestions. 

We are using 2.6.1 version and we shall check with V2.8.0 with overlay file, you had mentioned. How ever the module is now in locked condition and connectivity is lost. Is there a way to unlock the module, so that after unlocking, we could try using the new version with overlay file suggested.

Thanks once again for your support.

Regards

Palaniappan

[Bendik Heiskel]

If the DCDC converters have been enabled, without the required inductors, the SoC is not powering up correctly. To recover a device in this state you will need to supply the DECD and DECR pins externaly, like you already have mentioned. Once these power rails are supplied externaly the nRF5340 should power up correctly and the device should then be recovered, to revert the regulators back to LDO mode. Once this have been done the external supply can be turned off, as the internal regulators should now be powering the device.

After this have been done you can flash a new application, but make sure the DCDC converter is disabled or you will need to do the recovery procedure again.

 

Best regards,

Bendik