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Add an example for accessing an SD/MMC card via SPI (#258)

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4
boards/rp-pico/Cargo.toml
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@ -28,6 +28,10 @@ cortex-m-rtic = "0.6.0-rc.4"
nb = "1.0"
i2c-pio = { git = "https://github.com/ithinuel/i2c-pio-rs", rev = "df06e4ac94a5b2c985d6a9426dc4cc9be0d535c0" }
heapless = "0.7.9"
embedded-sdmmc = { git = "https://github.com/rust-embedded-community/embedded-sdmmc-rs.git" }
defmt = "0.2.0"
defmt-rtt = "0.2.0"
[features]
default = ["boot2", "rt"]

6
boards/rp-pico/README.md
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@ -94,6 +94,12 @@ interrupts when USB data arrives.
Demonstrates emulating a USB Human Input Device (HID) Mouse. The mouse
cursor will jiggle up and down.
### [pico_spi_sd_card](./examples/pico_spi_sd_card.rs)
Example that shows how to use the
[embedded_sdmmc crate](https://github.com/rust-embedded-community/embedded-sdmmc-rs)
with the Raspberry Pi Pico.
## Contributing
Contributions are what make the open source community such an amazing place to

381
boards/rp-pico/examples/pico_spi_sd_card.rs Normal file
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@ -0,0 +1,381 @@
//! # Pico SD Card Example
//!
//! Reads and writes a file from/to the SD Card that is formatted in FAT32.
//! This example uses the SPI0 device of the Raspberry Pi Pico on the
//! pins 4,5,6 and 7. If you don't use an external 3.3V power source,
//! you can connect the +3.3V output on pin 36 to the SD card.
//!
//! SD Cards up to 2TB are supported by the `embedded_sdmmc` crate.
//! I've tested this with a 64GB micro SD card.
//!
//! You need to format the card with an regular old FAT32 filesystem
//! and also make sure the first partition has the right type. This is how your
//! `fdisk` output should look like:
//!
//! ```text
//! fdisk /dev/sdj
//!
//! Welcome to fdisk (util-linux 2.34).
//! Changes will remain in memory only, until you decide to write them.
//! Be careful before using the write command.
//!
//! Command (m for help): Disk /dev/sdj:
//! 59,49 GiB, 63864569856 bytes, 124735488 sectors
//! Disk model: SD/MMC/MS/MSPRO
//! Units: sectors of 1 * 512 = 512 bytes
//! Sector size (logical/physical): 512 bytes / 512 bytes
//! I/O size (minimum/optimal): 512 bytes / 512 bytes
//! Disklabel type: dos
//! Disk identifier: 0x00000000
//!
//! Device Boot Start End Sectors Size Id Type
//! /dev/sdj1 2048 124735487 124733440 59,5G c W95 FAT32 (LBA)
//! ```
//!
//! The important bit here is the _Type_ with `W95 FAT32 (LBA)`, other types
//! are rejected by the `embedded_sdmmc` filesystem implementation.
//!
//! Formatting the partition can be done using `mkfs.fat`:
//!
//! $ mkfs.fat /dev/sdj1
//!
//! In the following ASCII art the SD card is also connected to 5 strong pull up
//! resistors. I've found varying values for these, from 50kOhm, 10kOhm
//! down to 5kOhm.
//! Stronger pull up resistors will eat more amperes, but also allow faster
//! data rates.
//!
//! ```text
//! +3.3V
//! Pull Ups ->||||
//! 4x[5kOhm]
//! ||| \
//! _______________ ||| \
//! | DAT2/NC 9\---o|| \ _|USB|_
//! | S DAT3/CS 1|---o+----+------SS--\ |1 R 40|
//! | D CMD/DI 2|----o----+-----MOSI-+-\ |2 P 39|
//! | VSS1 3|-- GND | | | GND-|3 38|- GND
//! | C VDD 4|-- +3.3V | /--SCK--+-+----SPI0 SCK-|4 P 37|
//! | A CLK/SCK 5|---------+-/ | \----SPI0 TX--|5 I 36|- +3.3V
//! | R VSS2 6|-- GND | /--MISO-+------SPI0 RX--|6 C |
//! | D DAT0/DO 7|---------o-/ \------SPI0 CSn-|7 O |
//! | DAT1/IRQ 8|-[5k]- +3.3V | |
//! """""""""""""""" | |
//! | |
//! .........
//! |20 21|
//! """""""
//! Symbols:
//! - (+) crossing lines, not connected
//! - (o) connected lines
//! ```
//!
//! The example can either be used with a probe to receive debug output
//! and also the LED is used as status output. There are different blinking
//! patterns.
//!
//! For every successful stage in the example the LED will blink long once.
//! If everything is successful (9 long blink signals), the example will go
//! into a loop and either blink in a _"short long"_ or _"short short long"_ pattern.
//!
//! If there are 5 different error patterns, all with short blinking pulses:
//!
//! - **2 short blink (in a loop)**: Block device could not be aquired, either
//! no SD card is present or some electrical problem.
//! - **3 short blink (in a loop)**: Card size could not be retrieved.
//! - **4 short blink (in a loop)**: Error getting volume/partition 0.
//! - **5 short blink (in a loop)**: Error opening root directory.
//! - **6 short blink (in a loop)**: Could not open file 'O.TST'.
//!
//! See the `Cargo.toml` file for Copyright and licence details.
#![no_std]
#![no_main]
// The macro for our start-up function
use cortex_m_rt::entry;
// info!() and error!() macros for printing information to the debug output
use defmt::*;
use defmt_rtt as _;
// Ensure we halt the program on panic (if we don't mention this crate it won't
// be linked)
use panic_halt as _;
// Pull in any important traits
use rp_pico::hal::prelude::*;
// Embed the `Hz` function/trait:
use embedded_time::rate::*;
// A shorter alias for the Peripheral Access Crate, which provides low-level
// register access
use rp_pico::hal::pac;
// Import the SPI abstraction:
use rp_pico::hal::spi;
// Import the GPIO abstraction:
use rp_pico::hal::gpio;
// A shorter alias for the Hardware Abstraction Layer, which provides
// higher-level drivers.
use rp_pico::hal;
// Link in the embedded_sdmmc crate.
// The `SdMmcSpi` is used for block level access to the card.
// And the `Controller` gives access to the FAT filesystem functions.
use embedded_sdmmc::{Controller, SdMmcSpi, TimeSource, Timestamp, VolumeIdx};
// Get the file open mode enum:
use embedded_sdmmc::filesystem::Mode;
/// A dummy timesource, which is mostly important for creating files.
#[derive(Default)]
pub struct DummyTimesource();
impl TimeSource for DummyTimesource {
// In theory you could use the RTC of the rp2040 here, if you had
// any external time synchronizing device.
fn get_timestamp(&self) -> Timestamp {
Timestamp {
year_since_1970: 0,
zero_indexed_month: 0,
zero_indexed_day: 0,
hours: 0,
minutes: 0,
seconds: 0,
}
}
}
// Setup some blinking codes:
const BLINK_OK_LONG: [u8; 1] = [8u8];
const BLINK_OK_SHORT_LONG: [u8; 4] = [1u8, 0u8, 6u8, 0u8];
const BLINK_OK_SHORT_SHORT_LONG: [u8; 6] = [1u8, 0u8, 1u8, 0u8, 6u8, 0u8];
const BLINK_ERR_2_SHORT: [u8; 4] = [1u8, 0u8, 1u8, 0u8];
const BLINK_ERR_3_SHORT: [u8; 6] = [1u8, 0u8, 1u8, 0u8, 1u8, 0u8];
const BLINK_ERR_4_SHORT: [u8; 8] = [1u8, 0u8, 1u8, 0u8, 1u8, 0u8, 1u8, 0u8];
const BLINK_ERR_5_SHORT: [u8; 10] = [1u8, 0u8, 1u8, 0u8, 1u8, 0u8, 1u8, 0u8, 1u8, 0u8];
const BLINK_ERR_6_SHORT: [u8; 12] = [1u8, 0u8, 1u8, 0u8, 1u8, 0u8, 1u8, 0u8, 1u8, 0u8, 1u8, 0u8];
fn blink_signals(
pin: &mut dyn embedded_hal::digital::v2::OutputPin<Error = core::convert::Infallible>,
delay: &mut cortex_m::delay::Delay,
sig: &[u8],
) {
for bit in sig {
if *bit != 0 {
pin.set_high().unwrap();
} else {
pin.set_low().unwrap();
}
let length = if *bit > 0 { *bit } else { 1 };
for _ in 0..length {
delay.delay_ms(100);
}
}
pin.set_low().unwrap();
delay.delay_ms(500);
}
fn blink_signals_loop(
pin: &mut dyn embedded_hal::digital::v2::OutputPin<Error = core::convert::Infallible>,
delay: &mut cortex_m::delay::Delay,
sig: &[u8],
) -> ! {
loop {
blink_signals(pin, delay, sig);
delay.delay_ms(1000);
}
}
#[entry]
fn main() -> ! {
info!("Program start");
// Grab our singleton objects
let mut pac = pac::Peripherals::take().unwrap();
let core = pac::CorePeripherals::take().unwrap();
// Set up the watchdog driver - needed by the clock setup code
let mut watchdog = hal::Watchdog::new(pac.WATCHDOG);
// Configure the clocks
//
// The default is to generate a 125 MHz system clock
let clocks = hal::clocks::init_clocks_and_plls(
rp_pico::XOSC_CRYSTAL_FREQ,
pac.XOSC,
pac.CLOCKS,
pac.PLL_SYS,
pac.PLL_USB,
&mut pac.RESETS,
&mut watchdog,
)
.ok()
.unwrap();
// The single-cycle I/O block controls our GPIO pins
let sio = hal::Sio::new(pac.SIO);
// Set the pins up according to their function on this particular board
let pins = rp_pico::Pins::new(
pac.IO_BANK0,
pac.PADS_BANK0,
sio.gpio_bank0,
&mut pac.RESETS,
);
// Set the LED to be an output
let mut led_pin = pins.led.into_push_pull_output();
// Setup a delay for the LED blink signals:
let mut delay = cortex_m::delay::Delay::new(core.SYST, clocks.system_clock.freq().integer());
// These are implicitly used by the spi driver if they are in the correct mode
let _spi_sclk = pins.gpio2.into_mode::<gpio::FunctionSpi>();
let _spi_mosi = pins.gpio3.into_mode::<gpio::FunctionSpi>();
let _spi_miso = pins.gpio4.into_mode::<gpio::FunctionSpi>();
let spi_cs = pins.gpio5.into_push_pull_output();
// Create an SPI driver instance for the SPI0 device
let spi = spi::Spi::<_, _, 8>::new(pac.SPI0);
// Exchange the uninitialised SPI driver for an initialised one
let spi = spi.init(
&mut pac.RESETS,
clocks.peripheral_clock.freq(),
16_000_000u32.Hz(),
&embedded_hal::spi::MODE_0,
);
info!("Aquire SPI SD/MMC BlockDevice...");
let mut sdspi = SdMmcSpi::new(spi, spi_cs);
blink_signals(&mut led_pin, &mut delay, &BLINK_OK_LONG);
// Next we need to aquire the block device and initialize the
// communication with the SD card.
let block = match sdspi.acquire() {
Ok(block) => block,
Err(e) => {
error!("Error retrieving card size: {}", defmt::Debug2Format(&e));
blink_signals_loop(&mut led_pin, &mut delay, &BLINK_ERR_2_SHORT);
}
};
blink_signals(&mut led_pin, &mut delay, &BLINK_OK_LONG);
info!("Init SD card controller...");
let mut cont = Controller::new(block, DummyTimesource::default());
blink_signals(&mut led_pin, &mut delay, &BLINK_OK_LONG);
info!("OK!\nCard size...");
match cont.device().card_size_bytes() {
Ok(size) => info!("card size is {} bytes", size),
Err(e) => {
error!("Error retrieving card size: {}", defmt::Debug2Format(&e));
blink_signals_loop(&mut led_pin, &mut delay, &BLINK_ERR_3_SHORT);
}
}
blink_signals(&mut led_pin, &mut delay, &BLINK_OK_LONG);
info!("Getting Volume 0...");
let mut volume = match cont.get_volume(VolumeIdx(0)) {
Ok(v) => v,
Err(e) => {
error!("Error getting volume 0: {}", defmt::Debug2Format(&e));
blink_signals_loop(&mut led_pin, &mut delay, &BLINK_ERR_4_SHORT);
}
};
blink_signals(&mut led_pin, &mut delay, &BLINK_OK_LONG);
// After we have the volume (partition) of the drive we got to open the
// root directory:
let dir = match cont.open_root_dir(&volume) {
Ok(dir) => dir,
Err(e) => {
error!("Error opening root dir: {}", defmt::Debug2Format(&e));
blink_signals_loop(&mut led_pin, &mut delay, &BLINK_ERR_5_SHORT);
}
};
info!("Root directory opened!");
blink_signals(&mut led_pin, &mut delay, &BLINK_OK_LONG);
// This shows how to iterate through the directory and how
// to get the file names (and print them in hope they are UTF-8 compatible):
cont.iterate_dir(&volume, &dir, |ent| {
info!(
"/{}.{}",
core::str::from_utf8(ent.name.base_name()).unwrap(),
core::str::from_utf8(ent.name.extension()).unwrap()
);
})
.unwrap();
blink_signals(&mut led_pin, &mut delay, &BLINK_OK_LONG);
let mut successful_read = false;
// Next we going to read a file from the SD card:
if let Ok(mut file) = cont.open_file_in_dir(&mut volume, &dir, "O.TST", Mode::ReadOnly) {
let mut buf = [0u8; 32];
let read_count = cont.read(&volume, &mut file, &mut buf).unwrap();
cont.close_file(&volume, file).unwrap();
if read_count >= 2 {
info!("READ {} bytes: {}", read_count, buf);
// If we read what we wrote before the last reset,
// we set a flag so that the success blinking at the end
// changes it's pattern.
if buf[0] == 0x42 && buf[1] == 0x1E {
successful_read = true;
}
}
}
blink_signals(&mut led_pin, &mut delay, &BLINK_OK_LONG);
match cont.open_file_in_dir(&mut volume, &dir, "O.TST", Mode::ReadWriteCreateOrTruncate) {
Ok(mut file) => {
cont.write(&mut volume, &mut file, b"\x42\x1E").unwrap();
cont.close_file(&volume, file).unwrap();
}
Err(e) => {
error!("Error opening file 'O.TST': {}", defmt::Debug2Format(&e));
blink_signals_loop(&mut led_pin, &mut delay, &BLINK_ERR_6_SHORT);
}
}
cont.free();
blink_signals(&mut led_pin, &mut delay, &BLINK_OK_LONG);
if successful_read {
info!("Successfully read previously written file 'O.TST'");
} else {
info!("Could not read file, which is ok for the first run.");
info!("Reboot the pico!");
}
loop {
if successful_read {
blink_signals(&mut led_pin, &mut delay, &BLINK_OK_SHORT_SHORT_LONG);
} else {
blink_signals(&mut led_pin, &mut delay, &BLINK_OK_SHORT_LONG);
}
delay.delay_ms(1000);
}
}