nrf_nvmc_write_words seems to crash on me.

[danatbws]

Hey, there.

I'm trying to use the NVMC to give me some persistent memory. I call init first, reads seem to work fine, but writes just don't seem to work.

So to the best of my knowledge, I have 512k of flash, so it goes from 0 to 0x80000. My image stops far below, so I thought I'd use the last 8k as my own playground.

Inside the project file, I found this setting:

linker_section_placement_macros="  ... FLASH_START=0x26000;FLASH_SIZE=0x5A000

so I reduced it to

linker_section_placement_macros=" ... FLASH_START=0x26000;FLASH_SIZE=0x58000

hoping that this would mean the image wouldn't interfere with my memory.

I use SDK15.0.0. The subroutine I'm going into is

void nrf_nvmc_write_words(uint32_t address, const uint32_t * src, uint32_t num_words)
{
    uint32_t i;

    // Enable write.
    NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen;
    __ISB();
    __DSB();

    for (i = 0; i < num_words; i++)
    {
        ((uint32_t*)address)[i] = src[i];
        wait_for_flash_ready();
    }

    NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren;
    __ISB();
    __DSB();
}


in nrf_nvmc.c.

address here is 0x7E000, src is 0x20007ff7c which looks right, and num_words is 1.
 
From single stepping it looks as if it crashes on the __ISB() call.

What am I missing here?

Regards,

Dan

[Jørgen Holmefjord]

Hi,

Are you using a softdevice in your application? From your FLASH_START address I guess you do. Note that access to the NVMC peripheral is restricted when the softdevice is enabled. You need to use the softdevice API sd_flash_write when writing flash when the softdevice is enabled.

Best regards,
Jørgen

[Jørgen Holmefjord]

That depends on the application. In many cases it is not acceptable to disable softdevice (connection will be lost, advertising stopped, etc.). In these cases, sd_flash API or fstorage/FDS will be the best alternative. NVMC is used when the softdevice is not active (there is no requirement for using BLE on our chips), and the softdevice writes direcly to the NVMC peripheral internally.

[danatbws]

OK, that makes.

Tak skal du have.

Dan