Using Flash Data Storage library with nrf52840+external memory (connected through the QSPI) as backend

Hello,

If you want to use the FDS library with qspi you need to write a new backend for the FDS.

There already is a softdevice backend and a non-softdevice backend. You can see how they are implemented if you compare the examples:

SDK\examples\peripheral\flash_fds\pca10056\s140

vs

SDK\examples\peripheral\flash_fds\pca10056\blank

The discussion in the thread that you linked to doesn't really conclude by using the FDS library at all, so that is probably also an option.

Best regards,

Edvin

But is work only in backend? Inside FDS library for reading from Flash, pointers to neccesary addresses in Flash are used, instead FStorage library's functions. For example in this function from fds.c:

// Reads a page tag, and determines if the page is used to store data or as swap.
static fds_page_type_t page_identify(uint32_t const * const p_page_addr)
{
    if (   (p_page_addr == NULL)    // Should never happen.
        || (p_page_addr[FDS_PAGE_TAG_WORD_0] != FDS_PAGE_TAG_MAGIC))    // here
    {
        return FDS_PAGE_UNDEFINED;
    }

    switch (p_page_addr[FDS_PAGE_TAG_WORD_1])
    {
        case FDS_PAGE_TAG_SWAP:
            return FDS_PAGE_SWAP;

        case FDS_PAGE_TAG_DATA:
            return FDS_PAGE_DATA;

        default:
            return FDS_PAGE_UNDEFINED;
    }
}

But is work only in backend? Inside FDS library for reading from Flash, pointers to neccesary addresses in Flash are used, instead FStorage library's functions. For example in this function from fds.c:

// Reads a page tag, and determines if the page is used to store data or as swap.
static fds_page_type_t page_identify(uint32_t const * const p_page_addr)
{
    if (   (p_page_addr == NULL)    // Should never happen.
        || (p_page_addr[FDS_PAGE_TAG_WORD_0] != FDS_PAGE_TAG_MAGIC))    // here
    {
        return FDS_PAGE_UNDEFINED;
    }

    switch (p_page_addr[FDS_PAGE_TAG_WORD_1])
    {
        case FDS_PAGE_TAG_SWAP:
            return FDS_PAGE_SWAP;

        case FDS_PAGE_TAG_DATA:
            return FDS_PAGE_DATA;

        default:
            return FDS_PAGE_UNDEFINED;
    }
}