NRF52832 doesn't enter sleep when using secure bootloader

[Rikard]

Our BLE app (based on ble_app_uart, example) on NRF52832 normally enters sleep by sd_power_system_off(). So this works as expected.

 

However, if we load the app by secure_bootloader_ble_s132_pca10040 the app will run but not enter sleep after call to
sd_power_system_off().  (Advertisement LED will be lit solid, no connection is present or done.)

 

We use flash page 0x7e to store some data at offset 0x200 can this interfere  with bootloader data in flash?

 

Any thoughts?

 

SDK version: nRF5_SDK_14.2.0_17b948a

[Vidar Berg]

Hi,

I suspect the unexpected wake-up might be caused by the BOOTLOADER_BUTTON which is initialized in the bootloader code. The button is configured with sense on transitions from high to low by default. Do you see the same if remove the button configuration in bootloader main.c->buttons_init() and change nrf_dfu_button_enter_check() to always return false?

[Rikard]

Hi Vidar,

Thanks for your reply. We have already disabled the BOOTLOADER_BUTTON so in our case this shouldn't be an issue. However we have good news:

We have tested to write to another flash page i.e: 0x5e instead of 0x7e. Then the device works as expected meaning it enters sleep after call to sd_power_system_off(). So writing to 0x5e was only a "qualified" guess that did the trick.

As this merely was a  guess we really need to know where it is ok to write when using the secure bootloader? Is there any docs describing this, because we haven't been able to find it

Thanks for your support

[Vidar Berg]

Hi,

I see, I first assumed that the program entered system OFF, but woke up immediately because of bootloader pin. Page 0x7e is reserved to the MBR params page inside the bootloader and should not be accessed by the application. I would suggest storing application data right below the bootloader as our flash modules do (fds and fstorage). Typical memory layout with the bootloader is shown here: Memory layout