Using FDS to save a Struct (Structure) and also reading it

[Ameer Usman]

I am trying to save and read a structure using FDS, how do I go about it?

I have the structure:

typedef struct
{
    uint8_t led_blink; //was bool
    uint8_t initial_adv_disable; //was bool
    uint8_t enable_ibeacon_Packet; //was bool
    uint8_t enable_cbeacon1_Health_Packet; //was bool
    uint8_t enable_cbeacon2_Proximity_Packet;  //was bool
    uint8_t enable_ibeacon_SOS_Packet; //was bool
    uint8_t enable_Mems; //was bool
}beacon_packet_struct;

My custom function for saving is:

int fds_write_struct(uint16_t file_id, uint16_t flash_key)
{
    ret_code_t ret;

    fds_record_t        record;
    fds_record_desc_t   record_desc;

    fds_record_desc_t desc = {0};
    fds_find_token_t  tok  = {0};

	if (flash_key == BEACON_STATE_KEY)
    {

        record.file_id              = FILE_ID;
        record.key                  = BEACON_STATE_KEY;
        record.data.p_data          = &beacon_flags;  //&beacon_flags;
        record.data.length_words    = ( sizeof(beacon_packet_struct) + 3 ) / sizeof(uint32_t);
      
        ret_code_t rc = fds_record_find(FILE_ID, BEACON_STATE_KEY , &desc, &tok);  //Search for record. Update if found else write a new one

        if (rc == FDS_SUCCESS)
        {   
            NRF_LOG_INFO("Similar BEACON STATE Variables Record was found thus it is being updated");
            rc = fds_record_update(&desc, &record);
            APP_ERROR_CHECK(rc);
        }
        else
        {
            ret_code_t ret = fds_record_write(&record_desc, &record);
            APP_ERROR_CHECK(ret);
            NRF_LOG_INFO("First time writing BEACON STATE record");
        }

        return 1;
    }
	
}

I call the function using below:

fds_write_struct(FILE_ID,BEACON_STATE_KEY);

But I get error 0x03 at:

ret_code_t ret = fds_record_write(&record_desc, &record);
APP_ERROR_CHECK(ret);

Suggestions would be greatly appreciated 

[Vidar Berg]

Hi,

The error code indicates that your .p_data pointer is not aligned to a 4-byte boundary as is required when flash writes. Try to define your 'beacon_flags' variable as shown below and see if you get the same error:

__ALIGN(4) beacon_packet_struct   beacon_flags;

[Ameer Usman]

Thanks Vidar but it worked once but upon performing erase and then again running it, it is giving error 0x02 on write function.

Thanks for sticking 

[Vidar Berg]

Ameer Usman said:

Also is my flash saving procedure (especially the length_words variable) ok?

 Yes, the length calculation looks ok. the +3 should ensure that the length is always rounded up.

Ameer Usman said:

As for reading I have done the following, can you verify if this is the right way to do it?

 It looks correct to me, but you need to test it.

[Ameer Usman]

This worked perfectly:

__ALIGN(4) beacon_packet_struct   beacon_flags;

Also the error of 0x02 I had was solved by putting a nrf_delay_ms(300); right after fds_init(); and thus it did not crash on the subsequent write.

Kudos Vidar! :)