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.
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.
rust
// Build an SD Card interface out of an SPI device, a chip-select pin and a delay object
let sdcard = embedded_sdmmc::SdCard::new(sdmmc_spi, sdmmc_cs, delay);
// Get the card size (this also triggers card initialisation because it's not been done yet)
println!("Card size is {} bytes", sdcard.num_bytes()?);
// Now let's look for volumes (also known as partitions) on our block device.
// To do this we need a Volume Manager. It will take ownership of the block device.
let mut volume_mgr = embedded_sdmmc::VolumeManager::new(sdcard, time_source);
// Try and access Volume 0 (i.e. the first partition).
// The volume object holds information about the filesystem on that volume.
// It doesn't hold a reference to the Volume Manager and so must be passed back
// to every Volume Manager API call. This makes it easier to handle multiple
// volumes in parallel.
let mut volume0 = volume_mgr.get_volume(embedded_sdmmc::VolumeIdx(0))?;
println!("Volume 0: {:?}", volume0);
// Open the root directory (passing in the volume we're using).
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);
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:
rust
// 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);
/path/foo/bar.txt style paths.The changelog has moved to CHANGELOG.md
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.
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.