Wrong initialization value in static variables

[Loosli]

Hi,

I'm developing a node based on the nRF52840-QIAA rev. B.

I'm using Eclipse Neon and GCC-toolchain for coding. Softdevice is S140 5.0.0.2 alpha and SDK is V14.2.

For Debugging I'm using an PCA10056 (nRF52840 PDK).

I'm always running into Error as soon as i try to interact with the softdevice. For example when calling nrf_sdh_enable_request().

While Debugging I've noticed that static variables like m_nrf_sdh_enabled (which is of type bool) don't seem to get initialized correctly.

Instead of "false", the value is an integer value. Depending on the configurations in sdk_config.h or the settings in the linker script for RAM start adress, this value changes.

Is this a Problem with the settings in linker script or what could it be?

Note: I'm using the default linkerscript provided in the examples library from ble_peripheral/ble_app_template 

Thanks for your help and advises!

Dominic

[ekrashtan]

All static variables are located in .bss segment. By default in startup code you should erase .bss section of RAM before code start.

FALSE value equal to 0, so I suppose your startup code has wrong init sequence. Please set the breakpoint at Reset_Handler address and check if _bss_start__ and __bss_end__ have the correct value. Also in .map file address of m_nrf_sdh_enabled shoul be between these values.

[Loosli]

Hi ekrashtan,

I tried to check your hints but when I set a breakpoint in the startup-file at the very beginning of the Reset_Handler, then this Breakpoint is never hit.

Some lines below the Reset_Handler I saw this comment in the startup code:

/* Call _start function provided by libraries.
 * If those libraries are not accessible, define __START as your entry point.
 */

Could this be a Problem, if i don't set this correctly?

__bss_start__ is at 0x200021fc

__bss_end__ is at 0x200035dc

m_nrf_sdh_enabled is at 0x20003368

So this variable is located between bss_start and bss_end.

RAM ORIGIN is set to 0x20002088 in linkerscript, as the correct address could only be known after the first enable of the softdevice as far as i know. This setting is made according to the ble_app_template from the sdk.

Best regards 

Dominic

[Loosli]

If desired, I can provide full linkerscript, .map-file, startup-code and makefile...

[ekrashtan]

Ok, just try to add symbol __STARTUP_CLEAR_BSS to your build and check again. Probably you use some library which already has .bss initialization on startup, but with different bss address, and this symbol will enable additional clean-up of your bss.
Also, check if your gcc_startup_nrf52.S compiled and linked.

[Loosli]

Thank you for your fast answer!

I tried Splitting the linker script in two parts, like in an old one that already worked and the initalisation works now fine.

The bss-sections are getting erased and the Reset_Handler is called as it should. 

Values of the static variables are now as they should be.

Problem with enabling the Softdevice stil exists, but I think this should be questioned in an other thread, as it has nothing to do with static variables...

Thank you for your Support! 

I'll mark your answer as solution.

Best regards, 

Dominic