Crate embedded_fat

embedded-sdmmc

An SD/MMC Library written in Embedded Rust

This crate is intended to allow you to read/write files on a FAT formatted SD card on your Rust Embedded device, as easily as using the SdFat Arduino library. It is written in pure-Rust, is #![no_std] and does not use alloc or collections to keep the memory footprint low. In the first instance it is designed for readability and simplicity over performance.

Using the crate

You will need something that implements the BlockDevice trait, which can read and write the 512-byte blocks (or sectors) from your card. If you were to implement this over USB Mass Storage, there’s no reason this crate couldn’t work with a USB Thumb Drive, but we only supply a BlockDevice suitable for reading SD and SDHC cards over SPI.

Features

• log: Enabled by default. Generates log messages using the log crate.
• defmt-log: By turning off the default features and enabling the defmt-log feature you can configure this crate to log messages over defmt instead.

You cannot enable both the log feature and the defmt-log feature.

Modules

blockdevice

Block Device support

fat

FAT16/FAT32 file system implementation

filesystem

Generic File System structures

Structs

Attributes

Indicates whether a directory entry is read-only, a directory, a volume label, etc.

Block

Represents a standard 512 byte block (also known as a sector). IBM PC formatted 5.25“ and 3.5“ floppy disks, SD/MMC cards up to 1 GiB in size and IDE/SATA Hard Drives up to about 2 TiB all have 512 byte blocks.

BlockCount

Represents the a number of blocks (or sectors). Add this to a BlockIdx to get an actual address on disk.

BlockIdx

Represents the linear numeric address of a block (or sector). The first block on a disk gets BlockIdx(0) (which usually contains the Master Boot Record).

ClusterId

Identifies a cluster on disk.

DirEntry

Represents a directory entry, which tells you about other files and directories.

Directory

Represents an open directory on disk.

FatVolume

Identifies a FAT16 or FAT32 Volume on the disk.

File

Represents an open file on disk.

ShortFileName

An MS-DOS 8.3 filename. 7-bit ASCII only. All lower-case is converted to upper-case by default.

Timestamp

Represents an instant in time, in the local time zone. TODO: Consider replacing this with POSIX time as a u32, which would save two bytes at the expense of some maths.

Volume

A VolumeManager wraps a block device and gives access to the FAT-formatted volumes within it.

Enums

Error

Represents all the ways the functions in this crate can fail.

FilenameError

Various filename related errors that can occur.

Mode

The different ways we can open a file.

VolumeType

This enum holds the data for the various different types of filesystems we support.

Constants

MAX_FILE_SIZE

Maximum file size supported by this library

Traits

BlockDevice

Represents a block device - a device which can read and write blocks (or sectors). Only supports devices which are <= 2 TiB in size.

TimeSource

Things that impl this can tell you the current time.