How to properly enable exFAT support in FAT filesystem with SDBlockdevice?

Hello all,

as mentioned in the title I would like to know how to enable exFAT instead of FAT32 within the FATFileSystem. I am using mbed CLI and mbedOS 6.7.0. The implementation of exFAT is available in ChanFS and within the mbed config file mbed_config.h I can find a corresponding


In mbed-os\storage\filesystem\fat\ChaN\mbed_lib.json I can enable the exFAT-functionality (“ff_fs_exfat” in line 116-118) but I was wondering if this is all and/or if I can enable/disable it somehow through custom_targets.json?

Anyway, the question is still: How to enable it properly? I could not find anything within the documentation.

Thank you for any hint on this.


You can add configs for the fat_chan library in your mbed_app.json as below:

    "target_overrides": {
        "*": {
            "platform.stdio-convert-newlines"   : true,
            "fat_chan.ff_fs_exfat"              : true,
            "fat_chan.ff_fs_reentrant"          : true

I have tried to test this with mbed-os-example-blockdevice, but got a lot of error. Probably, the exFAT on the Mbed OS is not tested.


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