Save Parameters/Variables

[xaerox]

Hello everybody :)
I'm not sure, that this question is already posted here. Is it possible to save variables in flash? Let's assume, we have a simple 12-bit A/D-converter and the values will be stored in a variable. We want to save this value in flash-device, to use this value again next startup (power off-->on).

I also think, using the flash device will not be the optimal solution. Should we use the SDRAM instead?

Kind regards,
Thomas.

[mon2]

Consider to use the new Microchip serial I2C EERAM (combination of SRAM and NVRAM with auto-save feature):

http://www.microchip.com/design-centers ... if-banners

[colin]

Hi Xaerox,

Using xflash you can limit the boot partition size by using the option --boot-partition-size. The rest of flash memory can then be used as a data partition. Using libflash you can then write and read to that data partition. There is also the xflash option --data which will enable you to pre-load the data partition with data useful to your application if you wish.

The AppNote https://www.xmos.com/download/private/A ... rc1%29.pdf details how to use these features with QSPI however SPI is near enough the same, except for port usage and using libflash as opposed to libquadflash.

Colin.

[xaerox]

hi everybody,
thank you for your helpful answers.
I think the libflash which colin has shown is my way to save some parameters. I think the main question is answered.
Thank you!

[ffomich]

Hi xearox,

be careful with fl_connectToDevice() - be sure you have enough time for this.

Code: Select all

timer tmr;
    unsigned start, end, connect_end, getSize_start, getSize_end, disconnect_start;
    int result = 0;

    tmr :> start;

    result = fl_connectToDevice(p_qflash, flash_devices, 1); // Connect to QSPI flash
    tmr :> connect_end;

    if (result == 0) // Connection OK
    {
        tmr :> getSize_start;
        result = ( (fl_getDataPartitionSize() > 0) ? 0 : 1); // Get DATA partition size
        tmr :> getSize_end;

        tmr :> disconnect_start;
        fl_disconnect(); // Disconnect from flash
    }
    tmr :> end;

Connect time (ticks) = connect_end - start = 247357
Read size time (ticks) = getSize_end - getSize_start = 18
Disconnect time (ticks) = end - disconnect_start = 24

1 tick @ 100 MHz = 10 ns
247357 ticks @ 100 MHz = ~2,5 ms !!!