5 unstable releases

0.3.0 Dec 16, 2019
0.2.1 Feb 19, 2019
0.2.0 Jan 24, 2019
0.1.1 Dec 23, 2018
0.1.0 Dec 23, 2018

#100 in Embedded development

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Used in less than 7 crates



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(),

Supported features

  • Open files in all supported methods from an open directory
  • Read data from open files
  • Write data to open files
  • Close files
  • Iterate root directory
  • Iterate sub-directories

Todo List (PRs welcome!)

  • Create new dirs
  • Delete files
  • Delete (empty) directories
  • Handle MS-DOS /path/foo/bar.txt style paths.


Unreleased changes (will be 0.3.1)

  • None

Version 0.3.0

  • Updated to v2 embedded-hal traits.
  • Added open support for all modes.
  • Added write support for files.
  • Added Info_Sector tracking for FAT32.
  • Change directory iteration to look in all the directory's clusters.
  • Added write_test and create_test.
  • De-duplicated FAT16 and FAT32 code (https://github.com/thejpster/embedded-sdmmc-rs/issues/10)

Version 0.2.1

  • Added readme=README.md to Cargo.toml

Version 0.2.0

  • Reduce delay waiting for response. Big speed improvements.

Version 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.


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.