examples: Add DMA examples for SPI, I2C, and UART to Tier 1 BSPs

Author: jbeaurivage

boards/atsame54_xpro/Cargo.toml

@@ -39,10 +39,17 @@ rtt-target = { version = "0.3", features = ["cortex-m"] }
 
 [features]
 default = ["rt", "atsamd-hal/same54p"]
+dma = ["atsamd-hal/dma"]
 rt = ["cortex-m-rt", "atsamd-hal/same54p-rt"]
 usb = ["atsamd-hal/usb", "usb-device"]
 can = ["atsamd-hal/can"]
 
+[[example]]
+name = "blinky_basic"
+
+[[example]]
+name = "blinky_rtic"
+
 [[example]]
 name = "mcan"
 required-features = ["can"]

boards/feather_m0/Cargo.toml

@@ -127,8 +127,19 @@ required-features = ["rtic"]
 
 [[example]]
 name = "uart"
+
+[[example]]
+name = "uart_dma_nonblocking"
+required-features = ["dma"]
+
+[[example]]
+name = "uart_dma_blocking"
 required-features = ["dma"]
 
 [[example]]
 name = "i2c"
 required-features = ["dma"]
+
+[[example]]
+name = "spi"
+required-features = ["dma"]

boards/feather_m0/examples/i2c.rs

@@ -1,4 +1,5 @@
-//! This example showcases the i2c module.
+//! This example showcases the i2c module, and uses DMA to perform I2C
+//! transactions.
 
 #![no_std]
 #![no_main]
@@ -23,8 +24,9 @@ use hal::ehal::i2c::I2c;
 use hal::fugit::RateExtU32;
 use hal::sercom::i2c;
 
-const LENGTH: usize = 1;
-const ADDRESS: u8 = 0x77;
+// This example is based on the BMP388 pressure sensor. Adjust the device and
+// register addresses to your liking
+const ADDRESS: u8 = 0x76;
 
 #[entry]
 fn main() -> ! {
@@ -48,31 +50,18 @@ fn main() -> ! {
     let channels = dmac.split();
     let chan0 = channels.0.init(PriorityLevel::Lvl0);
 
-    let buf_src: &'static mut [u8; LENGTH] =
-        cortex_m::singleton!(: [u8; LENGTH] = [0x00; LENGTH]).unwrap();
-    let buf_dest: &'static mut [u8; LENGTH] =
-        cortex_m::singleton!(: [u8; LENGTH] = [0x00; LENGTH]).unwrap();
-
     let gclk0 = clocks.gclk0();
     let sercom3_clock = &clocks.sercom3_core(&gclk0).unwrap();
     let pads = i2c::Pads::new(sda, scl);
     let mut i2c = i2c::Config::new(&pm, peripherals.sercom3, pads, sercom3_clock.freq())
         .baud(100.kHz())
-        .enable();
+        .enable()
+        .with_dma_channel(chan0);
 
-    let mut buffer = [0x00; 1];
+    let mut received = [0x00; 1];
 
     // Test writing then reading from an I2C chip
-    i2c.write_read(ADDRESS, &[0x00], &mut buffer).unwrap();
-
-    // Test writing then reading using DMA
-    let init_token = i2c.init_dma_transfer().unwrap();
-    let xfer = i2c.send_with_dma(ADDRESS, init_token, buf_src, chan0, |_| {});
-    let (chan0, _buf_src, mut i2c) = xfer.wait();
-
-    let init_token = i2c.init_dma_transfer().unwrap();
-    let xfer = i2c.receive_with_dma(ADDRESS, init_token, buf_dest, chan0, |_| {});
-    let (_chan0, _i2c, _buf_dest) = xfer.wait();
+    i2c.write_read(ADDRESS, &[0x00; 8], &mut received).unwrap();
 
     loop {
         // Go to sleep

boards/feather_m0/examples/spi.rs

@@ -0,0 +1,84 @@
+//! This example showcases the spi module, and uses DMA to perform SPI
+//! transactions.
+
+#![no_std]
+#![no_main]
+
+#[cfg(not(feature = "use_semihosting"))]
+use panic_halt as _;
+#[cfg(feature = "use_semihosting")]
+use panic_semihosting as _;
+
+use feather_m0 as bsp;
+
+use bsp::entry;
+use bsp::hal;
+use bsp::pac;
+
+use pac::Peripherals;
+
+use hal::clock::GenericClockController;
+use hal::dmac::{DmaController, PriorityLevel};
+use hal::ehal::spi::SpiBus;
+use hal::fugit::RateExtU32;
+
+#[entry]
+fn main() -> ! {
+    let mut peripherals = Peripherals::take().unwrap();
+    let mut clocks = GenericClockController::with_internal_32kosc(
+        peripherals.gclk,
+        &mut peripherals.pm,
+        &mut peripherals.sysctrl,
+        &mut peripherals.nvmctrl,
+    );
+
+    let mut pm = peripherals.pm;
+    let dmac = peripherals.dmac;
+    let pins = bsp::Pins::new(peripherals.port);
+
+    // Take SPI pins
+    let (miso, mosi, sclk) = (pins.miso, pins.mosi, pins.sclk);
+
+    // Setup DMA channels for later use
+    let mut dmac = DmaController::init(dmac, &mut pm);
+    let channels = dmac.split();
+    let chan0 = channels.0.init(PriorityLevel::Lvl0);
+    let chan1 = channels.1.init(PriorityLevel::Lvl0);
+
+    // Create a Spi with DMA enabled
+    let mut spi = bsp::spi_master(
+        &mut clocks,
+        100.kHz(),
+        peripherals.sercom4,
+        &mut pm,
+        sclk,
+        mosi,
+        miso,
+    )
+    .with_dma_channels(chan0, chan1);
+
+    loop {
+        let mut source = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15];
+        let mut dest = [0xff; 16];
+
+        // Read words into a buffer. The words sent will be be NOP word
+        // (by default, 0x00).
+        spi.read(&mut dest).unwrap();
+
+        // Send words from a buffer
+        spi.write(&source).unwrap();
+
+        // Simultaneously read and write from different buffers.
+        //
+        // If the source is longer than the destination, the words read
+        // in excess will be discarded.
+        //
+        // If the destination is longer than the source, the excess words
+        // sent will be the NOP word (by default, 0x00).
+        spi.transfer(&mut dest, &source).unwrap();
+
+        // Simultaneously read and write from the same buffer
+        // Cannot use DMA for this method, so it reverts to word by word transfers.
+        spi.transfer_in_place(&mut source).unwrap();
+    }
+}

boards/feather_m0/examples/uart.rs

@@ -1,9 +1,9 @@
-//! This example showcases the uart module.
+//! This example shows how to use the UART to perform transfers using the
+//! embedded-hal-nb traits.
 
 #![no_std]
 #![no_main]
 
-use cortex_m::asm;
 #[cfg(not(feature = "use_semihosting"))]
 use panic_halt as _;
 #[cfg(feature = "use_semihosting")]
@@ -16,7 +16,6 @@ use hal::nb;
 
 use bsp::{entry, periph_alias, pin_alias};
 use hal::clock::GenericClockController;
-use hal::dmac::{DmaController, PriorityLevel};
 use hal::ehal_nb::serial::{Read, Write};
 use hal::fugit::RateExtU32;
 
@@ -33,16 +32,8 @@ fn main() -> ! {
     );
 
     let mut pm = peripherals.pm;
-    let dmac = peripherals.dmac;
     let pins = bsp::Pins::new(peripherals.port);
 
-    // Setup DMA channels for later use
-    let mut dmac = DmaController::init(dmac, &mut pm);
-    let channels = dmac.split();
-
-    let chan0 = channels.0.init(PriorityLevel::Lvl0);
-    let chan1 = channels.1.init(PriorityLevel::Lvl0);
-
     // Take peripheral and pins
     let uart_sercom = periph_alias!(peripherals.uart_sercom);
     let uart_rx = pin_alias!(pins.uart_rx);
@@ -61,47 +52,27 @@ fn main() -> ! {
     // Split uart in rx + tx halves
     let (mut rx, mut tx) = uart.split();
 
-    // Get a 50 byte buffer to store data to send/receive
-    const LENGTH: usize = 50;
-    let rx_buffer: &'static mut [u8; LENGTH] =
-        cortex_m::singleton!(: [u8; LENGTH] = [0x00; LENGTH]).unwrap();
-    let tx_buffer: &'static mut [u8; LENGTH] =
-        cortex_m::singleton!(: [u8; LENGTH] = [0x00; LENGTH]).unwrap();
+    // Make buffers to store data to send/receive
+    let mut rx_buffer = [0x00; 50];
+    let mut tx_buffer = [0x00; 50];
 
     // For fun, store numbers from 0 to 49 in buffer
     for (i, c) in tx_buffer.iter_mut().enumerate() {
         *c = i as u8;
     }
 
-    // Send data in a blocking way
-    for c in tx_buffer.iter() {
-        nb::block!(tx.write(*c)).unwrap();
-    }
-
-    // We'll now receive data in a blocking way
-    rx.flush_rx_buffer();
-    for c in rx_buffer.iter_mut() {
-        *c = nb::block!(rx.read()).unwrap();
-    }
-
-    // Finally, we'll receive AND send data at the same time with DMA
-
-    // Setup a DMA transfer to send our data asynchronously.
-    // We'll set the waker to be a no-op
-    let tx_dma = tx.send_with_dma(tx_buffer, chan0, |_| {});
-
-    // Setup a DMA transfer to receive our data asynchronously.
-    // Again, we'll set the waker to be a no-op
-    let rx_dma = rx.receive_with_dma(rx_buffer, chan1, |_| {});
-
-    // Wait for transmit DMA transfer to complete
-    let (_chan0, _tx_buffer, _tx) = tx_dma.wait();
-
-    // Wait for receive DMA transfer to complete
-    let (_chan1, _rx_buffer, _rx) = rx_dma.wait();
-
     loop {
-        // Go to sleep
-        asm::wfi();
+        // Send data. We block on each byte, but we could also perform some tasks while
+        // waiting for the byte to finish sending.
+        for c in tx_buffer.iter() {
+            nb::block!(tx.write(*c)).unwrap();
+        }
+
+        // Receive data. We block on each byte, but we could also perform some tasks
+        // while waiting for the byte to finish sending.
+        rx.flush_rx_buffer();
+        for c in rx_buffer.iter_mut() {
+            *c = nb::block!(rx.read()).unwrap();
+        }
     }
 }

boards/feather_m0/examples/uart_dma_blocking.rs

@@ -0,0 +1,82 @@
+//! This example shows how to use the UART to perform blocking transfers using
+//! DMA and the embedded-io traits.
+
+#![no_std]
+#![no_main]
+
+#[cfg(not(feature = "use_semihosting"))]
+use panic_halt as _;
+#[cfg(feature = "use_semihosting")]
+use panic_semihosting as _;
+
+use bsp::hal;
+use bsp::pac;
+use feather_m0 as bsp;
+
+use bsp::{entry, periph_alias, pin_alias};
+use hal::clock::GenericClockController;
+use hal::dmac::{DmaController, PriorityLevel};
+use hal::embedded_io::{Read, Write};
+use hal::fugit::RateExtU32;
+
+use pac::Peripherals;
+
+#[entry]
+fn main() -> ! {
+    let mut peripherals = Peripherals::take().unwrap();
+    let mut clocks = GenericClockController::with_internal_32kosc(
+        peripherals.gclk,
+        &mut peripherals.pm,
+        &mut peripherals.sysctrl,
+        &mut peripherals.nvmctrl,
+    );
+
+    let mut pm = peripherals.pm;
+    let dmac = peripherals.dmac;
+    let pins = bsp::Pins::new(peripherals.port);
+
+    // Setup DMA channels for later use
+    let mut dmac = DmaController::init(dmac, &mut pm);
+    let channels = dmac.split();
+
+    let chan0 = channels.0.init(PriorityLevel::Lvl0);
+    let chan1 = channels.1.init(PriorityLevel::Lvl0);
+
+    // Take peripheral and pins
+    let uart_sercom = periph_alias!(peripherals.uart_sercom);
+    let uart_rx = pin_alias!(pins.uart_rx);
+    let uart_tx = pin_alias!(pins.uart_tx);
+
+    // Setup UART peripheral and attach DMA channels
+    let uart = bsp::uart(
+        &mut clocks,
+        9600.Hz(),
+        uart_sercom,
+        &mut pm,
+        uart_rx,
+        uart_tx,
+    )
+    .with_rx_channel(chan0)
+    .with_tx_channel(chan1);
+
+    // Split uart in rx + tx halves
+    let (mut rx, mut tx) = uart.split();
+
+    loop {
+        // Make buffers to store data to send/receive
+        let mut rx_buffer = [0x00; 50];
+        let mut tx_buffer = [0x00; 50];
+
+        // For fun, store numbers from 0 to 49 in buffer
+        for (i, c) in tx_buffer.iter_mut().enumerate() {
+            *c = i as u8;
+        }
+
+        // Send data using DMA...
+        tx.write(&tx_buffer).unwrap();
+
+        //...and receive using DMA
+        rx.flush_rx_buffer();
+        rx.read(&mut rx_buffer).unwrap();
+    }
+}