A SD/MMC library with FAT16/FAT32 support, suitable for Embedded Rust systems
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examples Can read files > 1 cluster in size. Dec 15, 2018
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.gitignore Skeleton. Nov 10, 2018
.travis.yml Use stable Rust - no weirdness here. Dec 15, 2018
Cargo.toml Fix CRC16 calculation. Nov 23, 2018
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Embedded SD/MMC

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.

let mut cont = embedded_sdmmc::Controller::new(embedded_sdmmc::SdMmcSpi::new(sdmmc_spi, sdmmc_cs));
write!(uart, "Init SD card...").unwrap();
match cont.device().init() {
    Ok(_) => {
        write!(uart, "OK!\nCard size...").unwrap();
        match cont.device().card_size_bytes() {
            Ok(size) => writeln!(uart, "{}", size).unwrap(),
            Err(e) => writeln!(uart, "Err: {:?}", e).unwrap(),
        write!(uart, "Volume 0...").unwrap();
        match cont.get_volume(0) {
            Ok(v) => writeln!(uart, "{:?}", v).unwrap(),
            Err(e) => writeln!(uart, "Err: {:?}", e).unwrap(),
    Err(e) => writeln!(uart, "{:?}!", e).unwrap(),

Todo List (PRs welcome!)

  • Open files read-only
  • Read data from open files
  • Close files
  • Open non-root dirs
  • Iterate non-root dirs
  • Open files for append
  • Append to files
  • Create new dirs
  • Create new files
  • Delete files
  • Delete (empty) directories
  • Handle MS-DOS /path/foo/bar.txt style paths.

Unreleased changes (will be 0.1.0)

  • Can read blocks from an SD Card using an embedded_hal::SPI device and a embedded_hal::OutputPin for Chip Select.
  • Can read partition tables and open a FAT32 or FAT16 formatted partition.
  • Can open and iterate the root directory of a FAT16 formatted partition.


  • Nothing released yet!


Licensed under either of

at your option.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.