Teensy 4.1 SD card compatibiliy questions

[amundsen]

Hello,

Before I start a project, I would like to know what is the maximum storage capacity a Teensy 4.1 can use on a SD card.

Also, can the Teensy read cards formatted with usual Windows partition schemes?

 

[WMXZ]

I have frequently used 1TB SD cards formatted with a PC (exFAT)

 

[PaulStoffregen]

Before I start a project, I would like to know what is the maximum storage capacity a Teensy 4.1 can use on a SD card.

2TB.

Also, can the Teensy read cards formatted with usual Windows partition schemes?

MBR and GPT are supported. I'm pretty sure we only support primary partitions in MBR, and only 1 commonly used GUID in GPT.

For filesystems, FAT, yes. NTFS, not so much.

All SD cards come pre-formatted with FAT (it's actually part of the SD spec to come FAT formatted) and MBR partition table. If you reformat with NTFS, it will not work. Some unusual FAT settings also may not be supported.

If you have reformatted in an incompatible way, there's a special SD card formatting program published by the SD association which formats a SD card exactly as the SD specs say. Bill (author of the SdFat library) has mentioned it several times. Apparently it guarantees formatting where the FAT clusters align best with the NAND flash blocks in the underlying media, which you don't necessarily get if you just use Microsoft's formatting.

Best to leave the SD card with its original formatting.

 

[MichaelMeissner]

2TB.

MBR and GPT are supported. I'm pretty sure we only support primary partitions in MBR, and only 1 commonly used GUID in GPT.

For filesystems, FAT, yes. NTFS, not so much.

All SD cards come pre-formatted with FAT (it's actually part of the SD spec to come FAT formatted) and MBR partition table. If you reformat with NTFS, it will not work. Some unusual FAT settings also may not be supported.

Cards that are 32GB or smaller are formatted with FAT32 and typically have the VFAT support on top of FAT32 (VFAT adds support for names other than the 8+3 uppercase).

Cards that are 64GB or larger are formatted with ExFat.