NRF_SDH_CLOCK_LF_SRC Changes Break app and DFU in 15.3 (from 15.2)

[dmacpro91]

I've finally worked around some funky bugs that only appeared after updating to 15.3. In my app, I had to change my clock source to RC or SYNTH to make it work (was hanging on enabling the softdevice). My XTAL setting worked fine in 15.2. When I got to working with DFU, I had some issues and tried everything mentioned on here (mergehex to fix the UICR/MBR bug, fixing the Makefile, etc.), but still couldn't get the DFUTarg device to appear. Loaded the debug version of the DFU module and stepped through it to find it failed to execute past the command to start the softdevice. It dawned on that this was probably the same issue that prevented my app from executing. After changing the clock source, everything worked as expected.

Now my question: What changed that makes the XTAL clock setting work fine in 15.2, but not 15.3? I'm using the DVK-BL652-SA device from Laird. Is there any issue using the SYNTH clock setting if power consumption isn't really a concern?

[Anders]

Hi dmacpro91

I'm curious if you could either explain the UICR/MBR bug a bit more or link to another post about it? I'm having a very similar issue as you, where I have the debug version of the secure bootloader (SDK v15.3.0) running as well as my own app. If I flash my nRF52832 with a hex file containing the combined app, bootloader debug build, bootloader settings, and softdevice hex files I also find that execution seems to stop when the bootloader passes control over to the softdevice.

I tried your solution and that didn't seem to fix it unfortunately, I'm looking for anything that I can try. The weird thing is that if I do the exact same thing but use the hex file for the release configuration of the debug bootloader everything works fine.

[Simonr]

Hi

This could be because you've not included the nrf_drv_clock.c in your project, as that file is used to define NRF_CLOCK_LFCLK_XTAL as CLOCK_LFCLKSRC_SRC_XTAL in SDK v.15.3, while SDK v.15.2 uses nrfx_clock.c instead. If that's not it, I'll need some more information about your application. Is it based on one of the SDK v.15.2 examples, and if so which one?

If current consumption isn't an issue, there shouldn't be any problem using the LFSYNTH. This way, the clock will have the accuracy of the HFCLK you're using, so keep in mind that the external HF clock has way better accuracy than the internal one.

Best regards,

Simon

[dmacpro91]

Here is one of the threads referencing the UICR/MBR issue: https://devzone.nordicsemi.com/f/nordic-q-a/45261/dfu-example-not-working/178253#178253

Hopefully that will resolve the issue for you.

[dmacpro91]

Thanks for the reply.  Initially when migrating to 15.3 from 15.2, I started with the stock 15.3 bootloader example.  Even this example showed the issue with the softdevice not launching on my end.  I'll test your suggestion and reply back later.

My projects were all based on 15.2 examples.  Mainly the ble_app_uart one.

[Anders]

Thank you!