RE: Boot loop during secure DFU upgrade with S140 from SDK 14.2.0 to SDK 15.0.0

tesc — Wed, 09 May 2018 11:10:41 GMT

Hi,

According to the release notes, s140_nrf52840_5.0.0-2.alpha uses MBR version 2.1.0, which has the following limitation:

The SV-calls sd_mbr_command_vector_table_base_set() and sd_mbr_command_copy_bl() are not supported
(DRGN-8197). Using these calls leads to undefined behavior.

What that means in practice is that bootloader update is not possible from the s140 5.0.0-2.alpha SoftDevice, as it leads to the behavior that you are experiencing. Since the MBR is not updated on SoftDevice update, the only option to fix this issue is to program MBR version 2.3.0, where the issue has been resolved, using a programmer. Preferably by using s140 version 6.0.0.

The issue only applies to alpha releases of the s140 SoftDevice, and was fixed prior to release of the (qualified) s140 v6.0.0 release which is the first production quality SoftDevice for the nRF52840.

Regards,
Terje