Non-volatile Data Management (NV DATA)

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1. Overview

The NV (non-volatile) data management module stores data in Flash with the following features:

• Supports independent storage of data items, each with a customizable size, identified by a 32‑bit ID.
• Easy to port: RTOS and Flash operations are stored in separate files.
• HotID mechanism for frequently used IDs to reduce Flash operations while saving RAM.
• Robust write with verification and error codes; application should retry on error.
• Power‑loss recovery to reuse last saved data.
• Interfaces include initialization, read, write, delete, and HotID registration.
• NVdata Flash erase block header uses 4 bytes; the lowest byte can serve as a version number. If version differs, the NVdata region will be erased.
• Data integrity is verified to ensure correctness as much as possible.

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2. Usage

This component exposes the following user APIs:

Function	Description
cinv_init	Initialize module
cinv_item_init	Initialize item
cinv_item_read	Read item data
cinv_item_write	Write item data
cinv_item_delete	Delete item data
cinv_register_hotid	Register as HotID

Example:

#include "ci_nvdata_manage.h"

/* Define the ID for the data to be stored */
#define NVDATA_ID_VOLUME                0x50000001 /* 'VOLU' */

void nvdata_test(void *p_arg)
{   
    uint16_t real_len;   
    uint8_t volume = 0x5;

    /* Register NVDATA_ID_VOLUME as HotID to speed up access at the cost of RAM.
       Omit if speed is not critical. */

    cinv_register_hotid(NVDATA_ID_VOLUME);

    /* Create a numeric item with initial value 0x5.
       The return value indicates whether this is the first write. */

    if(CINV_ITEM_UNINIT == cinv_item_init(NVDATA_ID_VOLUME, sizeof(volume), &volume))
    {
        mprintf("first write\n");
    }

    /* Read the item value */

    if(CINV_OPER_SUCCESS != cinv_item_read(NVDATA_ID_VOLUME, sizeof(volume), &volume, &real_len))
    {
        mprintf("read error\n");
        while(1);
    }
    else
    {
        mprintf("volume = 0x%x, real_len is %d\n", volume, real_len);
        volume ++;
    }

    /* Update (write) the item value */

    if(CINV_OPER_SUCCESS != cinv_item_write(NVDATA_ID_VOLUME,real_len, &volume))
    {
        mprintf("write error\n");
        while(1);
    }
}

Tip

NVDATA_ID_VOLUME is a user‑defined macro and uniquely identifies the item. Registering it as a HotID consumes extra memory but speeds up read/write from Flash. Use based on actual needs.

3. API Reference