Issue with Application loading after migration from SDK 14.2 to SDK 15.3

[Adam Gordon]

I am running custom firmware on a custom board using an nRF52832 chip. I have encountered an issue after migrating my project from SDK 14.2 to SDK 15.3. The issue is that my application is not starting and it occurs on two different occasions:

1. After successfully performing an OTA DFU using a secure ble bootloader, my application doesn't run. The DFU is performed successfully but after nrf_bootloader_app_start() is called, is does not load my application.
2. If my application is loaded and running on my device and the device is removed from power and then plugged back in, the application does not startup.

With that being said, if I merge the .hex files of the BL, BL settings, SD, and APP and flash them onto my device using nrfjprog, my application is loaded and runs properly. If I then remove my device from power and plug it back in, the application no longer starts. Loading the same bootloader and softdevice and then performing a DFU with my application does not successfully start my application either.

I tried both above scenarios with an example app from the SDK (blinky) which I modified to run on my custom board, and everything worked correctly. I was able to perform a DFU and have the application start, and if I power cycled the device, the app restarted.

This functionality used to work fine with my app when it was using SDK 14.2, it has only broken since migrating to SDK 15.3. Is there something that has changed that I need to be aware of?

Any help with the issue would be greatly appreciated.

[Hung Bui]

Hi Adam, 

You may want to re-compile the bootloader with optimization to level 0 (so you can debug) and step into the bootloader code to see why it doesn't jump to your application after a reset. I suspect your application may change (due to a flash operation ? ) causing CRC32 check doesn't match ?  

Do you have any special function in your application related to UICR ? flash ? 

I assume your application works fine if you only flash the softdevice and the application ? 

[Adam Gordon]

Hi Hung,

Thank you for getting back to me! Unfortunately it's not just after a reset that my application does not start, it is also after a DFU.

We have no special function related to UICR. We use FDS in our application, but that is it.

Do you mean from SES? If so then yes, our application works fine if flashed from Segger with just the application and softdevice. It does not work if just the softdevice and application are flashed using nrfjprog (and then the device reset).

However, what is odd, is that if we take all of the .hex files of the bootloader, bootloader settings, softdevice, and application and merge them using mergehex and then flash them onto the device using nrfjprog and reset, the application runs and works fine. Even if I flash the .hex files each individually everything runs fine.

But if I flash just the bootloader and softdevice and then successfully perform a DFU, the bootloader does not jump to my application code. Is there a reason why it would work when I flash all the components together and not when I perform a DFU?

[Adam Gordon]

Hung Bui said:

Strip down your application to a minimal function, for example blinking an LED. If it works after an DFU, you can start testing with more feature until it stop.

The error occurs when calling fds_init(). Specifically, pages_init() returns with a value of NO_PAGES.

This, however, only occurs after bootloader code was run. If I erase all and then run only the application, pages_init() returns FRESH_INSTALL and things work normally.

From this, I have come to understand that because the bootloader writes to flash storage, my application is no longer able to initialize fds properly. How can I get around this issue?

EDIT: To further isolate the issue, and to hopefully allow you to reproduce it on your end, I programmed and ran the secure ble bootloader example from the SDK (with softdevice loaded) on a PCA10040 DK and then ran the flash_fds example from the SDK and encountered the same issue. If I then erased all on the device and ran the flash_fds example on it's own, it functioned properly. If I loaded and ran the bootloader and then ran the flash_fds example, I would get the issue with CLI output of:

<info> app: FDS example started.
<info> app: Initializing fds...
<error> app: Fatal error
<warning> app: System reset

Debugging through the flash_fds code, I see the same issue where fds_init() returns FDS_ERR_NO_PAGES.

[Hung Bui]

Hi Adam, 

I think we are getting closer to the problem. 

I'm suspecting the change in the start address of the bootloader can cause the issue on the new SDK. The reason is that fds would detect where the bootloader is (or if the bootloader exist) and then allocate the data space accordingly. 

We need to check if it allocated the area correctly. Could you add a breakpoint inside flash_subsystem_init() and check what's the end_addr and the  start_addr inside flash_bounds_set() function  ? 

Also could you do a hex dump (nrfjprog --readcode) and check if there is any data stored in the pages right before the bootloader (0x78000 or 0x72000 if you use bootloader debug version)

Regarding reproducing the issue with flash_fds example, could you let me know how you tested it ? 

Did you flash softdevice and bootloader. And then you did DFU update using a .zip file of the flash_fds example ?

Or you flash the flash_fds using the programmer and change the bootloader setting to accept that image ? 

[Adam Gordon]

Hi Hung,

So I ran my application without loading the bootloader and the start and end addresses were 0x7D000 and 0x80000. I then ran the application with the bootloader loaded and the start and end addresses were the same. I'm assuming this is the issue since it overlaps with the bootloader's location in memory?

Also, I checked for data stored using Segger and there doesn't seem to be anything stored right before the bootloader (see image below).

As for reproducing the issue with the flash_fds example, I wish I could have tested it by performing a DFU, however a DFU package for the flash_fds example was not provided in the test images in the SDK, and since I do not have the private key of the SDK, I could not generate a DFU package on my own.

I actually tested it two ways with the same results. The first way I did it was load the bootloader project file into Segger and build and run. And then load the flash_fds project file into Segger and build and run. Also, I tried using nrfjprog to program the softdevice (with --chiperase) and then program the bootloader right after (with --reset). And then once that ran I used Segger to build and run the flash_fds example.

EDIT: I tried hardcoding the end_addr value in flash_bounds_set() to 0x78000 to see if that would resolve the issue and I got some interesting results. If I load and run the bootloader (with softdevice loaded) using nrfjprog and then use Segger to build and run my application, it now loads and runs properly! Also, if I use nrfjprog to load the softdevice, bootloader, and bootloader settings and then reset the chip, allow the bootloader to run, and then load my application and reset the chip, the application runs properly. HOWEVER, I tried only loading and running the bootloader+softdevice to then load the application using OTA DFU from the bootloader and the application did NOT start. It's also worth mentioning that in the instances where I got the application to start running properly (with the hardcoded value), the application did not restart after a power cycle.

[Hung Bui]

Hi Adam, 

I assume you have your own private key use with your bootloader ? You mentioned that you can do OTA DFU with your application ? 

If you want to test the flash_fds you should either generate a .zip file of the hex or generate at bootloader setting. I attached here the .zip file and the bootloader setting I used. Saw no issue with the example. 

Could you please double check what exactly return in flash_end_addr() ?  when you have the bootloader installed and the application installed. 

Especially check if you have this inside app_util.h

#define BOOTLOADER_ADDRESS      ((*(uint32_t *)MBR_BOOTLOADER_ADDR) == 0xFFFFFFFF ? *MBR_UICR_BOOTLOADER_ADDR : *(uint32_t *)MBR_BOOTLOADER_ADDR) 

The bootloader address should point to the start address of your bootloader. 

I suspect that since we don't write to MBR_UICR_BOOTLOADER_ADDR  any more it could cause an issue if you don't have correct  BOOTLOADER_ADDRESS       macro . 

flash_fds.hexbootloader_settings.hex

[Adam Gordon]

Hi Hung,

Good point, I have my own set of public/private keys that I will use with the examples to test the flash_fds app. 

As for the BOOTLOADER_ADDRESS macro, unfortunately I’m currently not in the office, but I looked into it a lot yesterday so will try to respond from memory to see if we can resolve this issue today. 

Yes we do have that macro inside app_util.h. I believe MBR_BOOTLOADER_ADDR was 0xFF8, pointing to a value of 0xFFFFFFFF. flash_end_addr() ended up returning 0x80000 because one of the lines of code has something that resembled two _sz being multiplied together. 

I’m sorry if that’s not 100% detailed or clear, I’m going off memory, but I wanted to be able to respond before you left for the day. I’m not in tomorrow and would like to get this resolved before the weekend, if possible. 

Thanks. 

[Adam Gordon]

Hi Hung,

I was able to be in touch with one of your colleagues in Anaheim today, and they helped me work through some of the details of this issue. Essentially the MBR_BOOTLOADER_ADDR loaded into memory location 0xFF8 was correctly set at 0x78000 when the softdevice and bootloader were loaded, but for some reason, when using Segger to load the application, the value in 0xFF8 was being overwritten to 0xFFFFFFFF.

However, that did not happen when the app was loaded via nrfjprog or via DFU (the value remained 0x78000). So that was significantly throwing off our troubleshooting. I am now working through the issue with that knowledge in mind to better isolate the main problem.

[Hung Bui]

Hi Adam, 

It's really strange that the application would touch the MBR area. Do you have any code that may set the attribute to the MBR address (0-0x1000) ? 

If you can provide the hex file that reproduce the problem I can have a look. 

[Daniel Veilleux]

Hello Hung, it wasn't that the application was modifying the MBR -- SES was erasing the MBR page and reflashing the SoftDevice when Adam started the debugger. Using Target -> Attach prevents SES from modifying the flash.

[Adam Gordon]

Hi Hung,

I'm sorry I wasn't more specific in my last reply. When I used Target -> Attach debugger, I no longer ran into the fds_init() issue that we were previously discussing (the BOOTLOADER_ADDRESS macro was returning the correct value). Unfortunately the issue of our application not starting after a successful DFU or after a power cycle persisted.

But now that the FDS issue was no longer clouding our troubleshooting, I continued trying to isolate the underlying issue further. I discovered some odd behaviour that I was hoping you might be able to help with.

I was trying to figure out why our application can load and run without issue when programmed using nrfjprog, but runs into issues when loaded via DFU. I will write out the steps I took and their results:

Build and Generate:

1. Build full application (nothing commented out) in debug build.

2. Generate DFU package using the following command (names changed for clarity):

nrfutil pkg generate --hw-version 52 --sd-req 0xB7 --application-version 1 --application application.hex --key-file private.key dfu_package.zip

3. Generate bootloader settings using the following command:

nrfutil settings generate --no-backup --family NRF52 --application application.hex --application-version 1 --bootloader-version 1 --bl-settings-version 1 bootloader_settings.hex

Load and Run Using NRFJPROG

1. Load and run the application using nrfjprog with the following commands:

nrfjprog --recover
nrfjprog --program s132_nrf52_6.1.1_softdevice.hex
nrfjprog --program ble_bootloader.hex
nrfjprog --program bootloader_settings.hex
nrfjprog --program application.hex
nrfjprog --reset

2. The application then starts and runs without issue. ️

 

Load and Run Using DFU

1. Load and run the bootloader using nrfjprog with the following commands:

nrfjprog --recover
nrfjprog --program s132_nrf52_6.1.1_softdevice.hex
nrfjprog --program ble_bootloader.hex

nrfjprog --reset

2. Open dfu_package.zip in nRF Toolbox iOS app and perform DFU on "DfuTarg".

3. The DFU progresses and completes without issue, but application's LED pattern never shows. 

4. Attach debugger in Segger and restart application from Main. Fails right away at NRF_LOG_INIT()

 

Test Again Using NRFJPROG

1. Repeat step 1 from "Load and Run Using NRFJPROG"

2. The application then starts and runs without issue. ️

3. Attach debugger in Segger and restart application from Main. Application runs without issue. ️

4. Unplug device from power.

5. Plug device back into power.

6. The application's LED pattern never shows

7. Attach debugger in Segger and restart application from Main. Fails right away at NRF_LOG_INIT()

 

Check to See if it is a Reset Issue

1. Repeat step 1 from "Load and Run Using NRFJPROG"

2. The application then starts and runs without issue. ️

3. Reset the device using nrfjprog with the following command

nrfjprog --reset

4. The application then starts and runs without issue. ️

 

It's worth mentioning that the issue isn't specific to NRF_LOG_INIT() since I've tried removing it and it just fails at the next init() function I call anyway. It's also worth mentioning that I tried resetting the device using nrfjprog --pinreset and it showed the same behaviour as a power cycle.

So I guess my question would be, is there a reason why the same application that loads and runs without issue using nrfjprog is not able to run properly when loaded and started via DFU? And is it the same reason why a properly loaded and running program no longer runs without issue after being power cycled?

 

The issue seems to present in a very similar fashion, but what would cause it?

 

Once again I really appreciate the help.

[Hung Bui]

Hi Adam, 

I assume when you do debugging you have followed the suggestion from Daniel so that Segger wouldn't erase MBR, Softdevice ? 

I am not sure what could be wrong here.

In the step "Test Again Using NRFJPROG" do you mean that if you connect and use SEGGER to debug, you have trouble after that ? What you can do is to make a hex dump (nrfjprog --readcode) before and after connecting Segger and then compare to see what changed. You would also need to read UICR (nrfjprog --readuicr)

For further debugging I would suggest: 

- Adding some more LED pattern inside the bootloader, so we know if the bootloader is executed, and if it forward to the application

- Strip down the application until it would work with DFU update. (for example only do LED blinking). To do that you can just add an infinite loop in your code. Then you can gradually more this loop down until you can reproduce the issue. 

If you can provide an minimal code that we can test here with the NRF52 DK it would be easier to find the root cause.