Hi Nordic
SDK15.2 based application and bootloader running on NRF52840 based UBlox module.
We have the following symptoms happening in the field:
- 2 channels of the watchdog are active with 120 seconds counters. We start a custom animation on an LED engine IC to indicate DFU in progress.
- Buttonless Secure DFU successfully started. Application only image, dual bank upgrade.
- After 100% is reached android app expects a reboot into the new image.
- LED animation keeps running, bootloader is no longer advertising, neither is the new image.
- After a power cycle the new application image is running.
We expect the bootloader is failing to start the new application image. Even though it's not advertising anymore, the watchdog must be petted or a reboot would follow.
The DFU inactivity timer is not causing a reset, even though no longer connected to the DFU controller.
Booting into the new image after power cycle proves it was copied into bank 1 and activated at some point. This could be after the reboot.
This is mentioned in the release notes for SDK 16.0 under bugfixes.
- Fixed a bug where resuming a DFU procedure with a disconnect (but no reset)in-between could leave the bootloader in a semi-locked state.
Does this explain our issue and can we be reasonably certain a bootloader based on SDK 16 will fix this?
How could we prevent the upgrade of the bootloader to lock the DFU in a similar state?
