Example Summary

This example shows how to use the Non-Volatile Storage (NVS) driver to read and write data to off-chip external flash memory. The external SPI flash is accessed by the NVS SPI driver.

Peripherals & Pin Assignments

When this project is built, the SysConfig tool will generate the TI-Driver configurations into the ti_drivers_config.c and ti_drivers_config.h files. Information on pins and resources used is present in both generated files. Additionally, the System Configuration file (*.syscfg) present in the project may be opened with SysConfig’s graphical user interface to determine pins and resources used.

• CONFIG_NVSEXTERNAL - Non-volatile storage used by a NVS driver instance.

BoosterPacks, Board Resources & Jumper Settings

For board specific jumper settings, resources and BoosterPack modifications, refer to the Board.html file.

If you’re using an IDE such as Code Composer Studio (CCS) or IAR, please refer to Board.html in your project directory for resources used and board-specific jumper settings.

The Board.html can also be found in your SDK installation:

<SDK_INSTALL_DIR>/source/ti/boards/<BOARD>

Example Usage

• Example output is generated through use of Display driver APIs. Refer to the Display driver documentation.

• Open a serial session (e.g. PuTTY, etc.) to the appropriate COM port.
  • The COM port can be determined via Device Manager in Windows or via ls /dev/tty* in Linux.

The connection will have the following settings:

    Baud-rate:     115200
    Data bits:          8
    Stop bits:          1
    Parity:          None
    Flow Control:    None

• Run the example.

• The example will output the region attributes as defined by CONFIG_NVSEXTERNAL.

• The example checks if the string, “SimpleLink SDK Non-Volatile Storage (NVS) SPI Example.” is present in non-volatile storage.
  • If present, the string is displayed to the UART console. The entire flash sector is then erased.
  • If not present, the string is written to the non-volatile storage.

• Disconnect the device from the debug session.

• When prompted, reset the device. This will cause the application to start over.

• The sector size and region size will vary depending on the device.

The following is example output assuming the string was not present in non-volatile storage:

    Sector Size: 0x1000
    Region Size: 0x4000

    Writing signature to SPI flash...
    Reset the device.
    ==================================================

The following is example output assuming the string is present in non-volatile storage:

    Sector Size: 0x1000
    Region Size: 0x4000

    SimpleLink SDK Non-Volatile Storage (NVS) SPI Example.
    Erasing SPI flash sector...
    Reset the device.
    ==================================================

Application Design Details

• The application utilizes a single thread to demonstrate using the non-volatile storage region defined by CONFIG_NVSEXTERNAL.

• CONFIG_NVSEXTERNAL defines non-volatile storage located on an off-chip external flash memory location. The memory definitions may be found in the board file. After NVS_open(), the nvsHandle is associated with the memory region defined by CONFIG_NVSEXTERNAL.

• A block of memory equal to the size of signature bytes is read from external flash and copied into RAM (buffer). This is performed through SPI transactions with the external flash device all contained inside the NVS SPI driver. The contents copied into buffer are compared to signature.
  • If equal, the application displays the signature to the UART console. It is important to note that the string was copied into RAM (buffer) during NVS_read(). This example displays the copied string stored in buffer. After the string is output to the UART console, the first sector in the NVS region is erased.
  • If not equal, the application writes the string, signature to the NVS region. This is performed through SPI transactions with the external flash device all contained inside the NVS SPI driver.

• At the end of execution, the application prompts the user to reset the device. Upon a reset, the contents of volatile memory (RAM) are lost. The example application restarts.

• The NVS_WRITE_ERASE flag is used with the NVS_write() API to ensure the flash sector is erased prior to performing a write. This flag will erase NVS_Attrs.sectorSize bytes of memory starting at the offset specified with NVS_write().

• The NVS_WRITE_POST_VERIFY flag is also used with the NVS_write() API to ensure the flash memory was successfully written.

FreeRTOS:

• Please view the FreeRTOSConfig.h header file for example configuration information.