Trouble trying to write data to the NRF52840

[coolerkid]

I am programming firmware for the NRF52840-DONGLE. I have been able to get all the features I'm developing working, except I am now just trying to store a simple 10 digit number to the device flash but I am unable to get it working no matter what I try.

ChatGPT has been able to help write a good amount of the code, which has worked perfectly, but it is unable to figure out this piece after many days of trying. I tried the NVS sample code too, which compiled but it crashes as soon as nvs_mount is called. When I say "crash", I'm not sure if it's technically crashing or something else. Basically if I run screen to view the logs, I see them fine, but as soon as I add nvs_mount(&fs) in the code and boot it, screen just starts and terminates with no log info at all. 

Any idea what could be wrong? Thanks 

[Vidar Berg]

Hello,

The bootloader pre-programmed on the dongle occupies the flash region from address 0xE0000 to 0x100000 and has write protection enabled. If the application attempts to write to this region, a fault exception will be raised. To prevent this, please try to reserve the flash area by including the nrf52840dongle_nrf52840_pm_static.yml file in your build as I did in this post:

 RE: nRF52840 dongle, BLE peripheral_uart example, SDK migration from 2.6.0 to 2.9.0  

Relevant changes:

diff --git a/boards/nrf52840dongle_nrf52840_pm_static.yml b/boards/nrf52840dongle_nrf52840_pm_static.yml
new file mode 100644
index 0000000..ae8446e
--- /dev/null
+++ b/boards/nrf52840dongle_nrf52840_pm_static.yml
@@ -0,0 +1,10 @@
+nrf5_bootloader:
+  address: 0xE0000
+  end_address: 0x100000
+  placement:
+    align:
+      start: 0x1000
+    before:
+    - end
+  region: flash_primary
+  size: 0x20000
\ No newline at end of file
diff --git a/sample.yaml b/sample.yaml
index dbf218c..4469dba 100644
--- a/sample.yaml
+++ b/sample.yaml
@@ -10,6 +10,7 @@ tests:
       thingy53/nrf5340/cpuapp/ns nrf21540dk/nrf52840 nrf54l15dk/nrf54l05/cpuapp
       nrf54l15dk/nrf54l10/cpuapp nrf54l15dk/nrf54l15/cpuapp
       nrf54h20dk/nrf54h20/cpuapp nrf54h20dk/nrf54h20/cpurad
+      nrf52840dongle/nrf52840
     integration_platforms:
       - nrf52dk/nrf52832
       - nrf52833dk/nrf52833
diff --git a/sysbuild.cmake b/sysbuild.cmake
new file mode 100644
index 0000000..aa2619b
--- /dev/null
+++ b/sysbuild.cmake
@@ -0,0 +1,3 @@
+if(SB_CONFIG_BOARD_NRF52840DONGLE)
+  set(PM_STATIC_YML_FILE ${CMAKE_CURRENT_LIST_DIR}/boards/nrf52840dongle_nrf52840_pm_static.yml CACHE INTERNAL "")
+endif()

Best regards,

Vidar

[coolerkid]

Thank you so much, that worked! I had been going back and fourth with AI for days on this and it couldn't figure this out, despite being nearly perfect on everything else.