NICLA SENSE ME (nRF52832) Undefined Behavior in Bootloader

[ijf1]

HI,

Following is the procedure to flash application we have tried:

1. Mass Erase
2. Write bootloader start address
3. Flash soft device
4. Flash bootloader 
5. Flash application 

The application loads perfectly when we follow the above procedure. I can re-flash application / bootloader when the board is on with application running.

We have implemented push button press to switch to boot mode. Once the board switches to boot mode, that is with ble_dfu_bootloader and if I try to flash application or re-flash the bootloader itself the bootloader crashes with signal interrupt.  The signal interrupt is randomly getting generated in bootloader. 

A reference screenshot is given below.

Also observed that, an led is kept ON to indicate boot mode. That led keeps glowing even if i flash application or re-flash bootloader. Button press is configured as interrupt, that also does not work in this scenario. The only way to get out is power cycle the board.

But if I power cycle the board, the recently flashed application get loaded successfully. 

Any suggestion would be really appreciated. Thanks.

Regards,

Ijaz  

[ijf1]

If I comment sd_softdevice_disable() function, its working fine.

please find below app_switch() implementation (in bootloader code):

{

sd_mbr_command_t com = { SD_MBR_COMMAND_INIT_SD, };

(void) sd_mbr_command(&com);

(void) sd_softdevice_disable();

void (*App_ResetJumpAddr)(void);

#Logic to check magic location for a specific key word. Depending on the key word found, it decides whether to stay in bootloader or load application

} 

[Vidar Berg]

The (void) sd_softdevice_disable(); function is redundant here as the Softdevice is being initialized right before by the MBR command.

I'm not sure why it is crashing though. Maybe the openocd script is changing the PC register when it programs the bootloader?

[ijf1]

Can you please explain how sd_softdevice_disable(); function is redundant. This code is being ported to nicla. I have not seen any enable api in bootloader. 

Is this disable api really required logically ?

As I understand after flashing the program, the openocd does attempt modify CPU state and PC.

[Vidar Berg]

I have not seen this code before nor do I know the reason for why sd_softdevice_disable(); was added in the first place. But I know that you can't issue the SD_MBR_COMMAND_INIT_SD command if the SD is already enabled.

ijf1 said:

As I understand after flashing the program, the openocd does attempt modify CPU state and PC.

The debugger should be configured so it does not alter the boot sequence described here: Master boot record and SoftDevice reset procedure. That is, it must let the execution start from address 0x4 and not directly from the bootloader.