Hard fault during interrupt request

[jeg223]

I am trying to port a project to an NRF52810.  The project uses a bootloader with a modified transport to work with a proprietary RF protocol.  The bootloader/app works on the nRF52833 and nRF52840 with different build configurations.  

The hard fault occurs when the app tries to jump to an interrupt.  It seems that the interrupt vectors are not being redirected correctly in the app. 

Is there something else that I'm missing?

Here are the section placements:

App:

FLASH_PH_START=0x0
FLASH_PH_SIZE=0x30000
RAM_PH_START=0x20000000
RAM_PH_SIZE=0x6000
FLASH_START=0x1000
FLASH_SIZE=0x30000
RAM_START=0x20000000
RAM_SIZE=0x6000
BL_FLASH_START=0x21000
BL_FLASH_SIZE=0xd000

Bootloader:

FLASH_PH_START=0x0
FLASH_PH_SIZE=0x30000
RAM_PH_START=0x20000000
RAM_PH_SIZE=0x6000
FLASH_START=0x1A000
FLASH_SIZE=0x14000
MBR_PARAMS_PAGE_START=0x2E000
MBR_PARAMS_PAGE_SIZE=0x1000
BOOT_SETTING_PAGE_START=0x2F000
BOOT_SETTING_PAGE_SIZE=0x1000
RAM_START=0x20000008
RAM_SIZE=0x5ff8

[jeg223]

It looks like it is an IBUSERR.  The fault happens when the interrupt fires.  If I step past the NVIC_SetPendingIRQ(SWI_IRQn); in app_timer.c, there is no fault until I run again.  Also, if I try to trigger other interrupts, I get the fault.

[Susheel Nuguru]

seems like you are in an interrupt context already when you are trying to trigger another interrupt. Can you check the interrupt number and priority from the SCB->ICSR register?

What other changes have you made apart from the memory linker file changes?

[jeg223]

Here is the SCB->ICSR register after the NVIC_SetPendingIRQ call, but before the interrupt fires:

Here it is after the hard fault:

Other things that changed in the bootloader are the startup files to use the 52810 versions.  I also modified nrf_bootloader_dfu_timers.c to use RTC0.  RTC1 is being used by app_timer and there is no RTC2 on the 810.

The app works when the flash start is 0x0000 instead of 0x1000.  If I set flash start to 0x1000 and load the mbr hex without the bootloader, it faults.  

[Susheel Nuguru]

Have you called this in your bootloader? Something like below

uint32_t nrf_dfu_mbr_init_sd(void)
{
    uint32_t ret_val;

    sd_mbr_command_t command =
    {
        .command = SD_MBR_COMMAND_INIT_SD
    };

    ret_val = sd_mbr_command(&command);

    return ret_val;
}

For more details, please look at this older thread.

[jeg223]

The bootloader is not calling that, but I am not using a SoftDevice.  When I add it to the nrf_bootloader_app_start function, the device seems hang for a bit then reset.