I've debugged this issue and found out that in such moments fs_buffer is
not filled fully - if I read the same cluster from pc - fat chain is ok.
Moreover I found that after a few steps in debug fs_buffer gets fully
filled as it is on an sd card. So it looks like the issue is related to
hardware read using dma (CONFIG_STM32F7_DMACAPABLE=y,
CONFIG_STM32F7_SDMMC_DMA=y).
MCU is stm32f767
It doesn't happen every time, but quite rare. Any thoughts where should I
look further?
пн, 7 сент. 2020 г. в 10:49, Oleg Evseev <ev.m...@gmail.com>:
> Hi all,
>
> I'm working with stm32f7 custom board and px4 firmware, but my concerns
> are with the NuttX FAT32 driver. I have an issue. PX4 logger module writes
> high rate data to SD card successfully awhile, until at some point write
> func return error 28 (“No space left on device”) while there is a lot of
> free space on a card (29GB out of 30GB).
>
> I had this error several times on two different SD-cards. I don't do a lot
> of tests, but it seems that SanDisk Extreme Pro is less prone - it can
> write 100+ Mbytes files without errors, while SanDisk Extreme usually
> breaks a little earlier.
> The board is on the table, no vibrations (at least any significant).
>
> I dig a little and can see that 'fat_write' try to extend the current
> cluster by one calling 'fat_extendchain' func that on existing chain
> extending verifies that this is a valid cluster by examining its start
> sector, but 'startsector = fat_getcluster(fs, cluster);' returns 0:
>
> else if (startsector < 2)
> {
> /* Oops.. this cluster does not exist. */
> return 0;
> }
>
> In 'fs_buffer' there is indeed 0 for this fatindex (see picture).
> [image: изображение.png]
>
>
> I didn't dig much in the driver and fat32 itself. What should I check,
> where it is useful to set breakpoints, etc.?
>
> Can any hardware issues be the reason for such error theoretically?
> Can any previous power shutdown and unfinished writings (in fact shutdowns
> can be on every launch and I already have several corrupted files), breaks
> FAT system itself in that way it can lead to this exact error for new
> sessions?
>
> Thanks in advance for any help!
>
> ---
> With regards, Oleg.
>
