Copying vector table to RAM unknown function at 0x00000000

[[email protected]]

I am using the nRF52840 DK with the s140 softdevice and am trying to copy the interrupt vector table to RAM to modify interrupts during run time.

I run the following function at the beginning of main()

static uint32_t vector_table_ram[VECTOR_TABLE_SIZE];

void vector_table_init()
{
    memcpy(vector_table_ram, (uint32_t *) (SCB->VTOR), VECTOR_TABLE_SIZE);

    __disable_irq();
    SCB->VTOR = (uint32_t)&vector_table_ram;    // Set VTOR to point to new vector table
    __enable_irq();
}

But I run into problems when running ble_stack_init(), specifically sd_softdevice_enable(). The Segger debugger jumps to disassembly and says unknown function at 0x00000000, the output also displays "T-bit of XPSR is 0 but should be 1. Changed to 1." 

After running my program with and without the above function it seems that values at flash start (0x00000000) are the same (0x0400, 0x200).

I know that modifying the vector table/MBR with the softdevice present can lead to deeper problems. I have tried using both __disable_irq() and CRITICAL_REGION_ENTER() before/after setting VTOR but still getting the same problem.

Any help would be great, and let me know if I can provide any more details.

[Turbo J]

Your vector_table_ram most likely has wrong alignment. VTOR requires unusual 128 byte alignment instead of the usual 4 bytes.

Try (if using gcc):

static uint32_t vector_table_ram[VECTOR_TABLE_SIZE] __attribute__ ((aligned (128)));

[[email protected]]

Worked like a charm! Thanks