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.

// Build an SD Card interface out of an SPI device
let mut spi_dev = embedded_sdmmc::SdMmcSpi::new(sdmmc_spi, sdmmc_cs);
// Try and initialise the SD card
let block_dev = spi_dev.acquire()?;
// The SD Card was initialised, and we have a `BlockSpi` object
// representing the initialised card.
write!(uart, "Card size is {} bytes", block_dev.card_size_bytes()?)?;
// Now let's look for volumes (also known as partitions) on our block device.
let mut cont = embedded_sdmmc::VolumeManager::new(block_dev, time_source);
// Try and access Volume 0 (i.e. the first partition)
let mut volume = cont.get_volume(embedded_sdmmc::VolumeIdx(0))?;
writeln!(uart, "Volume 0: {:?}", v)?;
// Open the root directory
let root_dir = volume_mgr.open_root_dir(&volume0)?;
// Open a file called "MY_FILE.TXT" in the root directory
let mut my_file = volume_mgr.open_file_in_dir(
    &mut volume0, &root_dir, "MY_FILE.TXT", embedded_sdmmc::Mode::ReadOnly)?;
// Print the contents of the file
while !my_file.eof() {
    let mut buffer = [0u8; 32];
    let num_read = volume_mgr.read(&volume0, &mut my_file, &mut buffer)?;
    for b in &buffer[0..num_read] {
        print!("{}", *b as char);
    }
}
volume_mgr.close_file(&volume0, my_file)?;
volume_mgr.close_dir(&volume0, root_dir)?;

Open directories and files

By default the VolumeManager will initialize with a maximum number of 4 open directories and files. This can be customized by specifying the MAX_DIR and MAX_FILES generic consts of the VolumeManager:

// Create a volume manager with a maximum of 6 open directories and 12 open files
let mut cont: VolumeManager<_, _, 6, 12> = VolumeManager::new_with_limits(block, time_source);

Supported features

• Open files in all supported methods from an open directory
• Open an arbitrary number of directories and files
• Read data from open files
• Write data to open files
• Close files
• Delete files
• Iterate root directory
• Iterate sub-directories
• Log over defmt or the common log interface (feature flags).

Todo List (PRs welcome!)

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

Changelog

The changelog has moved to CHANGELOG.md

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)

• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

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.