FDS Implementation

[Somesh Burkule]

Hello Everyone,

I am trying to implement fds in nrf52832 with sdk 15.2. getting some issues. I am using 5 record key's and 1 file id.

Before coming to that, Can anyone explain what is file id, record id and record key? I have read documentations but not clear about it.

[Jared]

Hi.

I actually do not agree, I think the specification explains is pretty well:

Record key	16 bits	Key that can be used to find the record. The value FDS_RECORD_KEY_DIRTY (0x0000) is reserved by the system to flag records that have been invalidated. See Restrictions on keys and IDs for further restrictions.

File ID

16 bits

ID of the file that the record is associated with. The value FDS_FILE_ID_INVALID (0xFFFF) is used by the system to identify records that have not been written correctly. See Restrictions on keys and IDs for further restrictions.

Record ID

32 bits

Unique identifier of the record.

So a specific Record will be stored in a file with a file ID. A file can have several records with the same record KEY but different record ID. Record ID is therefore unique, record KEY and file ID however is not. Which means that you can have several records stored with the same file ID and record KEY but with a unique record ID. You use record KEY and file ID when you want to access a Record. 

Documentation.

regards

Jared 

[Somesh Burkule]

Jared said:

You use record KEY and file ID when you want to access a Record. 

Thanks Jared.

So we can use fds without using Record Id?

[Jared]

You don't need to pass the Record id when you want to access a record since this is something that will be handled by the module. Only Record Key and File Id is necessary.

[Somesh Burkule]

What if I use file I'd and same record key?

[Jared]

From documentation: 

fds_record_find (): This function finds the first record in a file that has the given record key. To search for the next record with the same key in the file, call the function again and supply the same fds_find_token_t structure to resume searching from the last record that was found.