1.39.10 Non-Volatile Memory Controller (NVMCTRL)

Using The Library

The main Flash memory can not be read while it is being erased or written, the CPU is stalled during the entire operation.

• All functions that modify the main Flash can be run from RAM memory to avoid CPU stall while main main Flash is being erased or written.

• Some devices has the Flash region that support read-while-write feature, it is called Data Flash. The user could execute code from main Flash while the the Data Flash is being erased or written.

The FLASH memory is divided into a number of physical rows, each containing four identically sized flash pages. Pages may be read or written to individually, however pages must be erased before being reprogrammed and the smallest granularity available for erasure is one single row.

NVM APIs are implemented to be non-blocking, the API will return immediately unless stalled by Flash operation. The user application can either use polling or callback method to indicate the transfer status.

• With polling, the application will need to continuously check if the flash operation is completed.

• With callback, the registered callback function will be called once the flash operation is completed. This means the application do not have to poll continuously.

Here is an example code to erase a row and program a page of memory using polling method

// Define a constant array in Flash.
// It must be aligned to row boundary and size has to be in multiple of rows
const uint8_t nvm_user_start_address[NVMCTRL_FLASH_ROWSIZE] __attribute__((aligned(NVMCTRL_FLASH_ROWSIZE),keep,externally_visible,space(prog)))= {0};

void populate_buffer(uint8_t* data)
{
    int i = 0;

    for (i = 0; i < (NVMCTRL_FLASH_PAGESIZE); i++)
    {
        *(data + i) = i;
    }
}

int main (void)
{
    uint8_t pageBuffer[NVMCTRL_FLASH_PAGESIZE] = {0};

    /*Populate pageBuffer to programmed*/
    populate_buffer(pageBuffer);

    while(NVMCTRL_IsBusy());

    /* Erase the row */
    NVMCTRL_RowErase((uint32_t)nvm_user_start_address);

    /* Wait for row erase  to complete */
    while(NVMCTRL_IsBusy());

    /* Program a page of data */
    NVMCTRL_PageWrite((uint32_t *)pageBuffer, (uint32_t)nvm_user_start_address);

    /* Wait for page program to compete */
    while(NVMCTRL_IsBusy());
}

Library Interface

Non-Volatile Memory Controller peripheral library provides the following interfaces:

Functions

Data types and constants