FreeRTOS+FAT for NOR SPI Flash

Kernel
1

hssathya wrote on Wednesday, June 20, 2018:

Hi All,

Would you recmmond FreeRTOS+FAT for SPI based NOR FLASH?
Is there a port already available for this?

Thanks,
Sathya

2

heinbali01 wrote on Wednesday, June 20, 2018:

Hi Sathya, you have probably heard that FAT is not an optimal file system to be implemented in NOR flash. But yes, at leat one person has implemented a driver that works well with FreeRTOS+FAT. I will ask if that person is willing to share his code.

If you do not need compatibility with FAT, you could also look around and find a file system especially designed for NOR flash.

3

loszi wrote on Thursday, June 21, 2018:

Hi Sathya,
Please find an FreeRTOS+FAT driver for Spansion s25fl164k attached.

As Hein mentioned - using NOR Flash + FAT fs (without some form of wear leveling) is not the best idea, because the intensive usage could kill the FAT area of the device. I recommend using it only for write rarely / read many application like storing configuration.

If you still want to use the driver, you need to customize / implement the following low level functions in the portable directory:

static uint8_t ucSpiTransferByte(uint8_t ucTX_Data)
static uint8_t ucSpiQuadReadByte(void)

and don’t forget to call:
BaseTypet xSpansionSPISyncCache(FFDiskt pxDisk, cachestampt xOlderThan);
before umount / power down for write back the changes.*

As you might see the code is quite experimental so no warranty at all, please use your own risk, and consider that each cache entry consumes 4KiB of RAM.

Regards, Szilárd

4

Dear Szilárd,

I came across this post but could not find the attached driver. I’d like to take a look to see if I might be able to use it.
Would it be ok, if you attach it again?

Best regards,

Rainer

5

Here is the file that was originally attached by Szilárd.
Spansion_S25FL1xxK.zip (14.5 KB)

6

Thanks for your immediate response!

Best regards,

Rainer