RE: pstorage page size

Petter Myhre — Wed, 14 Jan 2015 11:35:08 GMT

Please add this as a new question and link to this one if it is relevant.

RE: pstorage page size

Dibin — Wed, 14 Jan 2015 11:25:14 GMT

Hi , Can I register for more than 1 page size ??, say i have block size of 16 and I need to reserver 2K memory. So I used count = 128. its returning a 07 error Thanks & Regards, DIbin

RE: pstorage page size

Petter Myhre — Fri, 10 Oct 2014 14:16:19 GMT

PSTORAGE_FLASH_PAGE_SIZE is the actual size of one page in flash, so you shouldn't change that.

You should be able to use a single flash page for this.

It is recommended that the block size is a multiple of the flash word size (4B), so if your largest variable is 20B(5*4B), you can use that as block size. It is also recommended that the block size is a divisor of the flash page size (1024B), that flash page size % block size = 0. This doesn't matter if you use less than 1 page of flash.

I'm assuming you are developing on one of our S110 BLE projects. Have you increased PSTORAGE_MAX_APPLICATIONS to 2? Your application + the device manager. This also increases the number of flash pages available to pstorage to 2 (actually 3, if you include the swap page). One for your application, one for the device manager.

Some variables:

static pstorage_handle_t        m_store_variables_base_handle;
static pstorage_handle_t        m_store_variables_curr_handle;
static int block_number = 0;
static uint8_t block0[4]  __attribute__((aligned(4)));

You must register your application in the pstorage module with something like this:

static void store_variables_init(void)
{
    uint32_t err_code;
    
    pstorage_module_param_t param;

    param.block_size  = 20;
    param.block_count = 7;
    param.cb          = store_variables_cb_handler;

    err_code = pstorage_register(&param, &m_store_variables_base_handle);
    APP_ERROR_CHECK(err_code);
}

You must define the pstorage event handler for your application:

static void store_variables_cb_handler(
                                pstorage_handle_t  * handle,
                                uint8_t              op_code,
                                uint32_t             result,
                                uint8_t            * p_data,
                                uint32_t             data_len)
{
    switch(op_code)
    {
        case PSTORAGE_STORE_OP_CODE:
           if (result == NRF_SUCCESS)
           {
              rdy_for_next = true; // Ready for next store operation
           }
           else
           {
               // Store operation failed. This must be handled
           }
           break;       
    }
}

rdy_for_next is a flag that is checked in the main loop:

// Enter main loop.
for (;;)
{
    if(rdy_for_next)
    {
        store_next_block();
    }
    err_code = sd_app_evt_wait();
    APP_ERROR_CHECK(err_code);
}

The store_next_block() can look like this:

static void store_next_block(void)
{
    rdy_for_next = false;
    uint32_t err_code;

    err_code = pstorage_block_identifier_get(&m_store_variables_base_handle, block_number, &m_store_variables_curr_handle);
    APP_ERROR_CHECK(err_code);
    err_code = pstorage_store(&m_store_variables_curr_handle, block0, 4,0);
    APP_ERROR_CHECK(err_code);
    block_number++;            
}

This should get you started, please add a comment if anything is unclear or if anything requires a better explanation.

RE: pstorage page size

ben38 — Fri, 10 Oct 2014 14:00:20 GMT

Thanks, some of my variables were in differents services. But I could probably refactor my code to use a single page.

A quick look at pstorage.c (where PSTORAGE_FLASH_PAGE_SIZE is used) doesn't indicate to me that it's a bad idea to change it... So there is probably something that I don't understand ? Can you explain me what is the problem ?

RE: pstorage page size

John — Fri, 10 Oct 2014 13:09:38 GMT

I am not a pstorage expert, but a quick look at how PSTORAGE_FLASH_PAGE_SIZE is used indicates changing it to something other than PSTORAGE_FLASH_PAGE_SIZE would result in some odd behaviors.

Why not just call pstorage_register once with the block count set to 7 and the block size set to 20? This should give you a single flash page with 7 blocks of 20 bytes to store your data.