first commit

.cargo/config

+[target.thumbv7m-none-eabi]
+# uncomment this to make `cargo run` execute programs on QEMU
+runner = "qemu-system-arm -cpu cortex-m3 -machine lm3s6965evb -nographic -semihosting-config enable=on,target=native -kernel"
+
+[target.'cfg(all(target_arch = "arm", target_os = "none"))']
+# uncomment ONE of these three option to make `cargo run` start a GDB session
+# which option to pick depends on your system
+# runner = "arm-none-eabi-gdb -q -x openocd.gdb"
+# runner = "gdb-multiarch -q -x openocd.gdb"
+# runner = "gdb -q -x openocd.gdb"
+
+rustflags = [
+  # LLD (shipped with the Rust toolchain) is used as the default linker
+  "-C", "link-arg=-Tlink.x",
+
+  # if you run into problems with LLD switch to the GNU linker by commenting out
+  # this line
+  # "-C", "linker=arm-none-eabi-ld",
+
+  # if you need to link to pre-compiled C libraries provided by a C toolchain
+  # use GCC as the linker by commenting out both lines above and then
+  # uncommenting the three lines below
+  # "-C", "linker=arm-none-eabi-gcc",
+  # "-C", "link-arg=-Wl,-Tlink.x",
+  # "-C", "link-arg=-nostartfiles",
+]
+
+[build]
+# Pick ONE of these compilation targets
+# target = "thumbv6m-none-eabi"    # Cortex-M0 and Cortex-M0+
+# target = "thumbv7m-none-eabi"    # Cortex-M3
+# target = "thumbv7em-none-eabi"   # Cortex-M4 and Cortex-M7 (no FPU)
+target = "thumbv7em-none-eabihf" # Cortex-M4F and Cortex-M7F (with FPU)

.gitignore

+**/*.rs.bk
+.#*
+.gdb_history
+Cargo.lock
+target/
+
+# editor files
+.vscode/*
+!.vscode/*.md
+!.vscode/*.svd
+!.vscode/launch.json
+!.vscode/tasks.json
+!.vscode/extensions.json
\ No newline at end of file

.vscode/README.md

+# VS Code Configuration
+
+Example configurations for debugging programs in-editor with VS Code.  
+This directory contains configurations for two platforms:
+
+ - `LM3S6965EVB` on QEMU
+ - `STM32F303x` via OpenOCD
+
+## Required Extensions
+
+If you have the `code` command in your path, you can run the following commands to install the necessary extensions.
+
+```sh
+code --install-extension rust-lang.rust
+code --install-extension marus25.cortex-debug
+```
+
+Otherwise, you can use the Extensions view to search for and install them, or go directly to their marketplace pages and click the "Install" button.
+
+- [Rust Language Server (RLS)](https://marketplace.visualstudio.com/items?itemName=rust-lang.rust)
+- [Cortex-Debug](https://marketplace.visualstudio.com/items?itemName=marus25.cortex-debug)
+
+## Use
+
+The quickstart comes with two debug configurations.
+Both are configured to build the project, using the default settings from `.cargo/config`, prior to starting a debug session.
+
+1. QEMU: Starts a debug session using an emulation of the `LM3S6965EVB` mcu.
+   - This works on a fresh `cargo generate` without modification of any of the settings described above.
+   - Semihosting output will be written to the Output view `Adapter Output`.
+   - `ITM` logging does not work with QEMU emulation.
+
+2. OpenOCD: Starts a debug session for a `STM32F3DISCOVERY` board (or any `STM32F303x` running at 8MHz).
+   - Follow the instructions above for configuring the build with `.cargo/config` and the `memory.x` linker script.
+   - `ITM` output will be written to the Output view `SWO: ITM [port: 0, type: console]` output.
+
+### Git
+
+Files in the `.vscode/` directory are `.gitignore`d by default because many files that may end up in the `.vscode/` directory should not be committed and shared.  
+If you would like to save this debug configuration to your repository and share it with your team, you'll need to explicitly `git add` the files to your repository.
+
+```sh
+git add -f .vscode/launch.json
+git add -f .vscode/tasks.json
+git add -f .vscode/*.svd
+```
+
+## Customizing for other targets
+
+For full documentation, see the [Cortex-Debug][cortex-debug] repository.
+
+### Device
+
+Some configurations use this to automatically find the SVD file.  
+Replace this with the part number for your device.
+
+```json
+"device": "STM32F303VCT6",
+```
+
+### OpenOCD Config Files
+
+The `configFiles` property specifies a list of files to pass to OpenOCD.
+
+```json
+"configFiles": [
+    "interface/stlink-v2-1.cfg",
+    "target/stm32f3x.cfg"
+],
+```
+
+See the [OpenOCD config docs][openocd-config] for more information and the [OpenOCD repository for available configuration files][openocd-repo].
+
+### SVD
+
+The SVD file is a standard way of describing all registers and peripherals of an ARM Cortex-M mCU.  
+Cortex-Debug needs this file to display the current register values for the peripherals on the device.  
+
+You can probably find the SVD for your device on the vendor's website.  
+
+
+For example, the STM32F3DISCOVERY board uses an mcu from the `STM32F303x` line of processors.  
+All the SVD files for the STM32F3 series are available on [ST's Website][stm32f3].  
+Download the [stm32f3 SVD pack][stm32f3-svd], and copy the `STM32F303.svd` file into `.vscode/`.  
+This line of the config tells the Cortex-Debug plug in where to find the file.
+
+```json
+"svdFile": "${workspaceRoot}/.vscode/STM32F303.svd",
+```
+
+For other processors, simply copy the correct `*.svd` file into the project and update the config accordingly.
+
+### CPU Frequency
+
+If your device is running at a frequency other than 8MHz, you'll need to modify this line of `launch.json` for the `ITM` output to work correctly.
+
+```json
+"cpuFrequency": 8000000,
+```
+
+### Other GDB Servers
+
+For information on setting up GDB servers other than OpenOCD, see the [Cortex-Debug repository][cortex-debug].
+
+[cortex-debug]: https://github.com/Marus/cortex-debug
+[stm32f3]: https://www.st.com/content/st_com/en/products/microcontrollers-microprocessors/stm32-32-bit-arm-cortex-mcus/stm32-mainstream-mcus/stm32f3-series.html#resource
+[stm32f3-svd]: https://www.st.com/resource/en/svd/stm32f3_svd.zip
+[openocd-config]: http://openocd.org/doc/html/Config-File-Guidelines.html
+[openocd-repo]: https://sourceforge.net/p/openocd/code/ci/master/tree/tcl/

.vscode/extensions.json

+{
+	// See https://go.microsoft.com/fwlink/?LinkId=827846 to learn about workspace recommendations.
+	// Extension identifier format: ${publisher}.${name}. Example: vscode.csharp
+
+	// List of extensions which should be recommended for users of this workspace.
+	"recommendations": [
+		"rust-lang.rust",
+		"marus25.cortex-debug",
+	],
+	// List of extensions recommended by VS Code that should not be recommended for users of this workspace.
+	"unwantedRecommendations": [
+		
+	]
+}
\ No newline at end of file

.vscode/launch.json

+{
+    /* 
+     * Requires the Rust Language Server (RLS) and Cortex-Debug extensions
+     * https://marketplace.visualstudio.com/items?itemName=rust-lang.rust
+     * https://marketplace.visualstudio.com/items?itemName=marus25.cortex-debug
+     */
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "type": "cortex-debug",
+            "request": "launch",
+            "name": "Debug (QEMU)",
+            "servertype": "qemu",
+            "cwd": "${workspaceRoot}",
+            "preLaunchTask": "cargo build",
+            "runToMain": true,
+            "executable": "./target/thumbv7m-none-eabi/debug/app",
+            /* Run `cargo build --example hello` and uncomment this line to run semi-hosting example */
+            //"executable": "./target/thumbv7m-none-eabi/debug/examples/hello",
+            "cpu": "cortex-m3",
+            "machine": "lm3s6965evb",
+        },
+        {
+            /* Configuration for the STM32F303 Discovery board */
+            "type": "cortex-debug",
+            "request": "launch",
+            "name": "Debug (OpenOCD)",
+            "servertype": "openocd",
+            "cwd": "${workspaceRoot}",
+            "preLaunchTask": "cargo build",
+            "runToMain": true,
+            "executable": "./target/thumbv7em-none-eabihf/debug/app",
+            /* Run `cargo build --example itm` and uncomment this line to run itm example */
+            // "executable": "./target/thumbv7em-none-eabihf/debug/examples/itm",
+            "device": "STM32F303VCT6",
+            "configFiles": [
+                "interface/stlink-v2-1.cfg",
+                "target/stm32f3x.cfg"
+            ],
+            "svdFile": "${workspaceRoot}/.vscode/STM32F303.svd",
+            "swoConfig": {
+                "enabled": true,
+                "cpuFrequency": 8000000,
+                "swoFrequency": 2000000,
+                "source": "probe",
+                "decoders": [
+                    { "type": "console", "label": "ITM", "port": 0 }
+                ]
+            }
+        }
+    ]
+}
\ No newline at end of file

.vscode/tasks.json

+{
+    // See https://go.microsoft.com/fwlink/?LinkId=733558 
+    // for the documentation about the tasks.json format
+    "version": "2.0.0",
+    "tasks": [
+        {
+            /*
+             * This is the default cargo build task,
+             * but we need to provide a label for it,
+             * so we can invoke it from the debug launcher.
+             */
+            "label": "cargo build",
+            "type": "process",
+            "command": "cargo",
+            "args": ["build"],
+            "problemMatcher": [
+                "$rustc"
+            ],
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            }
+        },
+        {
+            "label": "cargo build --release",
+            "type": "process",
+            "command": "cargo",
+            "args": ["build", "--release"],
+            "problemMatcher": [
+                "$rustc"
+            ],
+            "group": "build"
+        },
+        {
+            "label": "cargo build --examples",
+            "type": "process",
+            "command": "cargo",
+            "args": ["build","--examples"],
+            "problemMatcher": [
+                "$rustc"
+            ],
+            "group": "build"
+        },
+        {
+            "label": "cargo build --examples --release",
+            "type": "process",
+            "command": "cargo",
+            "args": ["build","--examples", "--release"],
+            "problemMatcher": [
+                "$rustc"
+            ],
+            "group": "build"
+        },
+        {
+            "label": "cargo clean",
+            "type": "process",
+            "command": "cargo",
+            "args": ["clean"],
+            "problemMatcher": [],
+            "group": "build"
+        },
+    ]
+}

Cargo.toml

+[package]
+authors = ["Per Lindgren <per.lindgren@ltu.se>"]
+edition = "2018"
+readme = "README.md"
+name = "app"
+version = "0.1.0"
+
+[dependencies]
+cortex-m = "0.6.0"
+cortex-m-rt = "0.6.10"
+cortex-m-semihosting = "0.3.3"
+panic-halt = "0.2.0"
+
+# Uncomment for the panic example.
+# panic-itm = "0.4.1"
+
+# Uncomment for the allocator example.
+# alloc-cortex-m = "0.3.5"
+
+# Uncomment for the device example.
+# Update `memory.x`, set target to `thumbv7em-none-eabihf` in `.cargo/config`,
+# and then use `cargo build --examples device` to build it.
+# [dependencies.stm32f3]
+# features = ["stm32f303", "rt"]
+# version = "0.7.1"
+
+# this lets you use `cargo fix`!
+[[bin]]
+name = "app"
+test = false
+bench = false
+
+[profile.release]
+codegen-units = 1 # better optimizations
+debug = true # symbols are nice and they don't increase the size on Flash
+lto = true # better optimizations

README.md

+# `cortex-m-quickstart`
+
+> A template for building applications for ARM Cortex-M microcontrollers
+
+This project is developed and maintained by the [Cortex-M team][team].
+
+## Dependencies
+
+To build embedded programs using this template you'll need:
+
+- Rust 1.31, 1.30-beta, nightly-2018-09-13 or a newer toolchain. e.g. `rustup
+  default beta`
+
+- The `cargo generate` subcommand. [Installation
+  instructions](https://github.com/ashleygwilliams/cargo-generate#installation).
+
+- `rust-std` components (pre-compiled `core` crate) for the ARM Cortex-M
+  targets. Run:
+
+``` console
+$ rustup target add thumbv6m-none-eabi thumbv7m-none-eabi thumbv7em-none-eabi thumbv7em-none-eabihf
+```
+
+## Using this template
+
+**NOTE**: This is the very short version that only covers building programs. For
+the long version, which additionally covers flashing, running and debugging
+programs, check [the embedded Rust book][book].
+
+[book]: https://rust-embedded.github.io/book
+
+0. Before we begin you need to identify some characteristics of the target
+  device as these will be used to configure the project:
+
+- The ARM core. e.g. Cortex-M3.
+
+- Does the ARM core include an FPU? Cortex-M4**F** and Cortex-M7**F** cores do.
+
+- How much Flash memory and RAM does the target device has? e.g. 256 KiB of
+  Flash and 32 KiB of RAM.
+
+- Where are Flash memory and RAM mapped in the address space? e.g. RAM is
+  commonly located at address `0x2000_0000`.
+
+You can find this information in the data sheet or the reference manual of your
+device.
+
+In this example we'll be using the STM32F3DISCOVERY. This board contains an
+STM32F303VCT6 microcontroller. This microcontroller has:
+
+- A Cortex-M4F core that includes a single precision FPU
+
+- 256 KiB of Flash located at address 0x0800_0000.
+
+- 40 KiB of RAM located at address 0x2000_0000. (There's another RAM region but
+  for simplicity we'll ignore it).
+
+1. Instantiate the template.
+
+``` console
+$ cargo generate --git https://github.com/rust-embedded/cortex-m-quickstart
+ Project Name: app
+ Creating project called `app`...
+ Done! New project created /tmp/app
+
+$ cd app
+```
+
+2. Set a default compilation target. There are four options as mentioned at the
+   bottom of `.cargo/config`. For the STM32F303VCT6, which has a Cortex-M4F
+   core, we'll pick the `thumbv7em-none-eabihf` target.
+
+``` console
+$ tail -n6 .cargo/config
+```
+
+``` toml
+[build]
+# Pick ONE of these compilation targets
+# target = "thumbv6m-none-eabi"    # Cortex-M0 and Cortex-M0+
+# target = "thumbv7m-none-eabi"    # Cortex-M3
+# target = "thumbv7em-none-eabi"   # Cortex-M4 and Cortex-M7 (no FPU)
+target = "thumbv7em-none-eabihf" # Cortex-M4F and Cortex-M7F (with FPU)
+```
+
+3. Enter the memory region information into the `memory.x` file.
+
+``` console
+$ cat memory.x
+/* Linker script for the STM32F303VCT6 */
+MEMORY
+{
+  /* NOTE 1 K = 1 KiBi = 1024 bytes */
+  FLASH : ORIGIN = 0x08000000, LENGTH = 256K
+  RAM : ORIGIN = 0x20000000, LENGTH = 40K
+}
+```
+
+4. Build the template application or one of the examples.
+
+``` console
+$ cargo build
+```
+
+## VS Code
+
+This template includes launch configurations for debugging CortexM programs with Visual Studio Code located in the `.vscode/` directory.  
+See [.vscode/README.md](./.vscode/README.md) for more information.  
+If you're not using VS Code, you can safely delete the directory from the generated project.
+
+# License
+
+This template is licensed under either of
+
+- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
+  http://www.apache.org/licenses/LICENSE-2.0)
+
+- MIT license ([LICENSE-MIT](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.
+
+## Code of Conduct
+
+Contribution to this crate is organized under the terms of the [Rust Code of
+Conduct][CoC], the maintainer of this crate, the [Cortex-M team][team], promises
+to intervene to uphold that code of conduct.
+
+[CoC]: https://www.rust-lang.org/policies/code-of-conduct
+[team]: https://github.com/rust-embedded/wg#the-cortex-m-team

examples/allocator.rs

+//! How to use the heap and a dynamic memory allocator
+//!
+//! This example depends on the alloc-cortex-m crate so you'll have to add it to your Cargo.toml:
+//!
+//! ``` text
+//! # or edit the Cargo.toml file manually
+//! $ cargo add alloc-cortex-m
+//! ```
+//!
+//! ---
+
+#![feature(alloc)]
+#![feature(alloc_error_handler)]
+#![no_main]
+#![no_std]
+
+extern crate alloc;
+extern crate panic_halt;
+
+use self::alloc::vec;
+use core::alloc::Layout;
+
+use alloc_cortex_m::CortexMHeap;
+use cortex_m::asm;
+use cortex_m_rt::entry;
+use cortex_m_semihosting::hprintln;
+
+// this is the allocator the application will use
+#[global_allocator]
+static ALLOCATOR: CortexMHeap = CortexMHeap::empty();
+
+const HEAP_SIZE: usize = 1024; // in bytes
+
+#[entry]
+fn main() -> ! {
+    // Initialize the allocator BEFORE you use it
+    unsafe { ALLOCATOR.init(cortex_m_rt::heap_start() as usize, HEAP_SIZE) }
+
+    // Growable array allocated on the heap
+    let xs = vec![0, 1, 2];
+
+    hprintln!("{:?}", xs).unwrap();
+
+    // exit QEMU
+    // NOTE do not run this on hardware; it can corrupt OpenOCD state
+    debug::exit(debug::EXIT_SUCCESS);
+
+    loop {}
+}
+
+// define what happens in an Out Of Memory (OOM) condition
+#[alloc_error_handler]
+fn alloc_error(_layout: Layout) -> ! {
+    asm::bkpt();
+
+    loop {}
+}

examples/crash.rs

+//! Debugging a crash (exception)
+//!
+//! Most crash conditions trigger a hard fault exception, whose handler is defined via
+//! `exception!(HardFault, ..)`. The `HardFault` handler has access to the exception frame, a
+//! snapshot of the CPU registers at the moment of the exception.
+//!
+//! This program crashes and the `HardFault` handler prints to the console the contents of the
+//! `ExceptionFrame` and then triggers a breakpoint. From that breakpoint one can see the backtrace
+//! that led to the exception.
+//!
+//! ``` text
+//! (gdb) continue
+//! Program received signal SIGTRAP, Trace/breakpoint trap.
+//! __bkpt () at asm/bkpt.s:3
+//! 3         bkpt
+//!
+//! (gdb) backtrace
+//! #0  __bkpt () at asm/bkpt.s:3
+//! #1  0x080030b4 in cortex_m::asm::bkpt () at $$/cortex-m-0.5.0/src/asm.rs:19
+//! #2  rust_begin_unwind (args=..., file=..., line=99, col=5) at $$/panic-semihosting-0.2.0/src/lib.rs:87
+//! #3  0x08001d06 in core::panicking::panic_fmt () at libcore/panicking.rs:71
+//! #4  0x080004a6 in crash::hard_fault (ef=0x20004fa0) at examples/crash.rs:99
+//! #5  0x08000548 in UserHardFault (ef=0x20004fa0) at <exception macros>:10
+//! #6  0x0800093a in HardFault () at asm.s:5
+//! Backtrace stopped: previous frame identical to this frame (corrupt stack?)
+//! ```
+//!
+//! In the console output one will find the state of the Program Counter (PC) register at the time
+//! of the exception.
+//!
+//! ``` text
+//! panicked at 'HardFault at ExceptionFrame {
+//!     r0: 0x2fffffff,
+//!     r1: 0x2fffffff,
+//!     r2: 0x080051d4,
+//!     r3: 0x080051d4,
+//!     r12: 0x20000000,
+//!     lr: 0x08000435,
+//!     pc: 0x08000ab6,
+//!     xpsr: 0x61000000
+//! }', examples/crash.rs:106:5
+//! ```
+//!
+//! This register contains the address of the instruction that caused the exception. In GDB one can
+//! disassemble the program around this address to observe the instruction that caused the
+//! exception.
+//!
+//! ``` text
+//! (gdb) disassemble/m 0x08000ab6
+//! Dump of assembler code for function core::ptr::read_volatile:
+//! 451     pub unsafe fn read_volatile<T>(src: *const T) -> T {
+//!    0x08000aae <+0>:     sub     sp, #16
+//!    0x08000ab0 <+2>:     mov     r1, r0
+//!    0x08000ab2 <+4>:     str     r0, [sp, #8]
+//!
+//! 452         intrinsics::volatile_load(src)
+//!    0x08000ab4 <+6>:     ldr     r0, [sp, #8]
+//! -> 0x08000ab6 <+8>:     ldr     r0, [r0, #0]
+//!    0x08000ab8 <+10>:    str     r0, [sp, #12]
+//!    0x08000aba <+12>:    ldr     r0, [sp, #12]
+//!    0x08000abc <+14>:    str     r1, [sp, #4]
+//!    0x08000abe <+16>:    str     r0, [sp, #0]
+//!    0x08000ac0 <+18>:    b.n     0x8000ac2 <core::ptr::read_volatile+20>
+//!
+//! 453     }
+//!    0x08000ac2 <+20>:    ldr     r0, [sp, #0]
+//!    0x08000ac4 <+22>:    add     sp, #16
+//!    0x08000ac6 <+24>:    bx      lr
+//!
+//! End of assembler dump.
+//! ```
+//!
+//! `ldr r0, [r0, #0]` caused the exception. This instruction tried to load (read) a 32-bit word
+//! from the address stored in the register `r0`. Looking again at the contents of `ExceptionFrame`
+//! we see that the `r0` contained the address `0x2FFF_FFFF` when this instruction was executed.
+//!
+//! ---
+
+#![no_main]
+#![no_std]
+
+extern crate panic_halt;
+
+use core::ptr;
+
+use cortex_m_rt::entry;
+
+#[entry]
+fn main() -> ! {
+    unsafe {
+        // read an address outside of the RAM region; this causes a HardFault exception
+        ptr::read_volatile(0x2FFF_FFFF as *const u32);
+    }
+
+    loop {}
+}

examples/device.rs

+//! Using a device crate
+//!
+//! Crates generated using [`svd2rust`] are referred to as device crates. These crates provide an
+//! API to access the peripherals of a device.
+//!
+//! [`svd2rust`]: https://crates.io/crates/svd2rust
+//!
+//! This example depends on the [`stm32f3`] crate so you'll have to
+//! uncomment it in your Cargo.toml.
+//!
+//! [`stm32f3`]: https://crates.io/crates/stm32f3
+//!
+//! ```
+//! $ edit Cargo.toml && tail $_
+//! [dependencies.stm32f3]
+//! features = ["stm32f303", "rt"]
+//! version = "0.7.1"
+//! ```
+//!
+//! You also need to set the build target to thumbv7em-none-eabihf,
+//! typically by editing `.cargo/config` and uncommenting the relevant target line.
+//!
+//! ---
+
+#![no_main]
+#![no_std]
+
+#[allow(unused_extern_crates)]
+extern crate panic_halt;
+
+use cortex_m::peripheral::syst::SystClkSource;
+use cortex_m_rt::entry;
+use cortex_m_semihosting::hprint;
+use stm32f3::stm32f303::{interrupt, Interrupt, NVIC};
+
+#[entry]
+fn main() -> ! {
+    let p = cortex_m::Peripherals::take().unwrap();
+
+    let mut syst = p.SYST;
+    let mut nvic = p.NVIC;
+
+    nvic.enable(Interrupt::EXTI0);
+
+    // configure the system timer to wrap around every second
+    syst.set_clock_source(SystClkSource::Core);
+    syst.set_reload(8_000_000); // 1s
+    syst.enable_counter();
+
+    loop {
+        // busy wait until the timer wraps around
+        while !syst.has_wrapped() {}
+
+        // trigger the `EXTI0` interrupt
+        NVIC::pend(Interrupt::EXTI0);
+    }
+}
+
+#[interrupt]
+fn EXTI0() {
+    hprint!(".").unwrap();
+}

examples/exception.rs

+//! Overriding an exception handler
+//!
+//! You can override an exception handler using the [`#[exception]`][1] attribute.
+//!
+//! [1]: https://rust-embedded.github.io/cortex-m-rt/0.6.1/cortex_m_rt_macros/fn.exception.html
+//!
+//! ---
+
+#![deny(unsafe_code)]
+#![no_main]
+#![no_std]
+
+extern crate panic_halt;
+
+use cortex_m::peripheral::syst::SystClkSource;
+use cortex_m::Peripherals;
+use cortex_m_rt::{entry, exception};
+use cortex_m_semihosting::hprint;
+
+#[entry]
+fn main() -> ! {
+    let p = Peripherals::take().unwrap();
+    let mut syst = p.SYST;
+
+    // configures the system timer to trigger a SysTick exception every second
+    syst.set_clock_source(SystClkSource::Core);
+    syst.set_reload(8_000_000); // period = 1s
+    syst.enable_counter();
+    syst.enable_interrupt();
+
+    loop {}
+}
+
+#[exception]
+fn SysTick() {
+    hprint!(".").unwrap();
+}

examples/hello.rs

+//! Prints "Hello, world!" on the host console using semihosting
+
+#![no_main]
+#![no_std]
+
+extern crate panic_halt;
+
+use cortex_m_rt::entry;
+use cortex_m_semihosting::{debug, hprintln};
+
+#[entry]
+fn main() -> ! {
+    hprintln!("Hello, world!").unwrap();
+
+    // exit QEMU
+    // NOTE do not run this on hardware; it can corrupt OpenOCD state
+   // debug::exit(debug::EXIT_SUCCESS);
+
+    loop {
+        
+    }
+}

examples/itm.rs

+//! Sends "Hello, world!" through the ITM port 0
+//!
+//! ITM is much faster than semihosting. Like 4 orders of magnitude or so.
+//!
+//! **NOTE** Cortex-M0 chips don't support ITM.
+//!
+//! You'll have to connect the microcontroller's SWO pin to the SWD interface. Note that some
+//! development boards don't provide this option.
+//!
+//! You'll need [`itmdump`] to receive the message on the host plus you'll need to uncomment two
+//! `monitor` commands in the `.gdbinit` file.
+//!
+//! [`itmdump`]: https://docs.rs/itm/0.2.1/itm/
+//!
+//! ---
+
+#![no_main]
+#![no_std]
+
+extern crate panic_halt;
+
+use cortex_m::{iprintln, Peripherals};
+use cortex_m_rt::entry;
+
+#[entry]
+fn main() -> ! {
+    let mut p = Peripherals::take().unwrap();
+    let stim = &mut p.ITM.stim[0];
+
+    iprintln!(stim, "Hello, world!");
+
+    loop {}
+}

examples/panic.rs

+//! Changing the panicking behavior
+//!
+//! The easiest way to change the panicking behavior is to use a different [panic handler crate][0].
+//!
+//! [0]: https://crates.io/keywords/panic-impl
+
+#![no_main]
+#![no_std]
+
+// Pick one of these panic handlers:
+
+// `panic!` halts execution; the panic message is ignored
+extern crate panic_halt;
+
+// Reports panic messages to the host stderr using semihosting
+// NOTE to use this you need to uncomment the `panic-semihosting` dependency in Cargo.toml
+// extern crate panic_semihosting;
+
+// Logs panic messages using the ITM (Instrumentation Trace Macrocell)
+// NOTE to use this you need to uncomment the `panic-itm` dependency in Cargo.toml
+// extern crate panic_itm;
+
+use cortex_m_rt::entry;
+
+#[entry]
+fn main() -> ! {
+    panic!("Oops")
+}

examples/test_on_host.rs

+//! Conditionally compiling tests with std and our executable with no_std.
+//!
+//! Rust's built in unit testing framework requires the standard library,
+//! but we need to build our final executable with no_std.
+//! The testing framework also generates a `main` method, so we need to only use the `#[entry]`
+//! annotation when building our final image.
+//! For more information on why this example works, see this excellent blog post.
+//! https://os.phil-opp.com/unit-testing/
+//!
+//! Running this example:
+//!
+//! Ensure there are no targets specified under `[build]` in `.cargo/config`
+//! In order to make this work, we lose the convenience of having a default target that isn't the
+//! host.
+//!
+//! cargo build --example test_on_host --target thumbv7m-none-eabi
+//! cargo test --example test_on_host
+
+#![cfg_attr(test, allow(unused_imports))]
+
+#![cfg_attr(not(test), no_std)]
+#![cfg_attr(not(test), no_main)]
+
+// pick a panicking behavior
+#[cfg(not(test))]
+extern crate panic_halt; // you can put a breakpoint on `rust_begin_unwind` to catch panics
+// extern crate panic_abort; // requires nightly
+// extern crate panic_itm; // logs messages over ITM; requires ITM support
+// extern crate panic_semihosting; // logs messages to the host stderr; requires a debugger
+
+use cortex_m::asm;
+use cortex_m_rt::entry;
+
+#[cfg(not(test))]
+#[entry]
+fn main() -> ! {
+    asm::nop(); // To not have main optimize to abort in release mode, remove when you add code
+
+    loop {
+        // your code goes here
+    }
+}
+
+fn add(a: i32, b: i32) -> i32 {
+    a + b
+}
+
+#[cfg(test)]
+mod test {
+  use super::*;
+
+  #[test]
+  fn foo() {
+    println!("tests work!");
+    assert!(2 == add(1,1));
+  }
+}

memory.x

+MEMORY
+{
+  /* NOTE 1 K = 1 KiBi = 1024 bytes */
+  /* TODO Adjust these memory regions to match your device memory layout */
+  /* These values correspond to the LM3S6965, one of the few devices QEMU can emulate */
+  FLASH : ORIGIN = 0x00000000, LENGTH = 256K
+  RAM : ORIGIN = 0x20000000, LENGTH = 64K
+}
+
+/* This is where the call stack will be allocated. */
+/* The stack is of the full descending type. */
+/* You may want to use this variable to locate the call stack and static
+   variables in different memory regions. Below is shown the default value */
+/* _stack_start = ORIGIN(RAM) + LENGTH(RAM); */
+
+/* You can use this symbol to customize the location of the .text section */
+/* If omitted the .text section will be placed right after the .vector_table
+   section */
+/* This is required only on microcontrollers that store some configuration right
+   after the vector table */
+/* _stext = ORIGIN(FLASH) + 0x400; */
+
+/* Example of putting non-initialized variables into custom RAM locations. */
+/* This assumes you have defined a region RAM2 above, and in the Rust
+   sources added the attribute `#[link_section = ".ram2bss"]` to the data
+   you want to place there. */
+/* Note that the section will not be zero-initialized by the runtime! */
+/* SECTIONS {
+     .ram2bss (NOLOAD) : ALIGN(4) {
+       *(.ram2bss);
+       . = ALIGN(4);
+     } > RAM2
+   } INSERT AFTER .bss;
+*/

openocd.cfg

+# Sample OpenOCD configuration for the STM32F3DISCOVERY development board
+
+# Depending on the hardware revision you got you'll have to pick ONE of these
+# interfaces. At any time only one interface should be commented out.
+
+# Revision C (newer revision)
+source [find interface/stlink-v2-1.cfg]
+
+# Revision A and B (older revisions)
+# source [find interface/stlink-v2.cfg]
+
+source [find target/stm32f3x.cfg]

openocd.gdb

+target extended-remote :3333
+
+# print demangled symbols
+set print asm-demangle on
+
+# set backtrace limit to not have infinite backtrace loops
+set backtrace limit 32
+
+# detect unhandled exceptions, hard faults and panics
+break DefaultHandler
+break HardFault
+break rust_begin_unwind
+# # run the next few lines so the panic message is printed immediately
+# # the number needs to be adjusted for your panic handler
+# commands $bpnum
+# next 4
+# end
+
+# *try* to stop at the user entry point (it might be gone due to inlining)
+break main
+
+monitor arm semihosting enable
+
+# # send captured ITM to the file itm.fifo
+# # (the microcontroller SWO pin must be connected to the programmer SWO pin)
+# # 8000000 must match the core clock frequency
+# monitor tpiu config internal itm.txt uart off 8000000
+
+# # OR: make the microcontroller SWO pin output compatible with UART (8N1)
+# # 8000000 must match the core clock frequency
+# # 2000000 is the frequency of the SWO pin
+# monitor tpiu config external uart off 8000000 2000000
+
+# # enable ITM port 0
+# monitor itm port 0 on
+
+load
+
+# start the process but immediately halt the processor
+stepi

same54.yaml

+name: SAME54
+manufacturer: ~
+variants:
+  - name: ATSAME54N19A
+    part: ~
+    memory_map:
+      - Ram:
+          range:
+            start: 536870912
+            end: 537067520
+          is_boot_memory: false
+      - Flash:
+          range:
+            start: 0
+            end: 524288
+          is_boot_memory: true
+    flash_algorithms:
+      - atsame54_512
+  - name: ATSAME54N20A
+    part: ~
+    memory_map:
+      - Ram:
+          range:
+            start: 536870912
+            end: 537133056
+          is_boot_memory: false
+      - Flash:
+          range:
+            start: 0
+            end: 1048576
+          is_boot_memory: true
+    flash_algorithms:
+      - atsame54_1024
+  - name: ATSAME54P19A
+    part: ~
+    memory_map:
+      - Ram:
+          range:
+            start: 536870912
+            end: 537067520
+          is_boot_memory: false
+      - Flash:
+          range:
+            start: 0
+            end: 524288
+          is_boot_memory: true
+    flash_algorithms:
+      - atsame54_512
+  - name: ATSAME54P20A
+    part: ~
+    memory_map:
+      - Ram:
+          range:
+            start: 536870912
+            end: 537133056
+          is_boot_memory: false
+      - Flash:
+          range:
+            start: 0
+            end: 1048576
+          is_boot_memory: true
+    flash_algorithms:
+      - ATSAME54_1024
+flash_algorithms:
+  ATSAME54_512:
+    name: ATSAME54_512
+    description: ATSAME54 512kB Flash
+    default: true
+    instructions: QVNHSkI0cHJVZ2NCMVNGS0NtRFBJaUJKRWdJS2dFNGlDb0lmU1VsRUNHQUFJSEJIQUNCd1J4cEpTR0ViU29xQVNvclNCL3pRU0dFWVNCRTRpSUJJaXNBSC9OQUlpazRoQ0VBQTBBRWdjRWN3dFJKTEQwemJIS09BWTRyYkIvelF5UnlKQ0FOR2lRQUM0Q0RLQ1I4Z3d3QXArdEZnWVFsSUR6aWdnR0NLd0FmODBDQ0tUaUVJUUFEUUFTQXd2UUFBSWdBQkFBQkFBRUVFQUFBQUVxVUFBQUFBQUFBQUFBQUE=
+    pc_init: 1
+    pc_uninit: 37
+    pc_program_page: 81
+    pc_erase_sector: 41
+    pc_erase_all: ~
+    data_section_offset: 160
+    flash_properties:
+      address_range:
+        start: 0
+        end: 524288
+      page_size: 512
+      erased_byte_value: 255
+      program_page_timeout: 100
+      erase_sector_timeout: 1000
+      sectors:
+        - size: 8192
+          address: 0
+  ATSAME54_1024:
+    name: ATSAME54_1024
+    description: ATSAME54 1024kB Flash
+    default: true
+    instructions: QVNHSkI0cHJVZ2NCMVNGS0NtRFBJaUJKRWdJS2dFNGlDb0lmU1VsRUNHQUFJSEJIQUNCd1J4cEpTR0ViU29xQVNvclNCL3pRU0dFWVNCRTRpSUJJaXNBSC9OQUlpazRoQ0VBQTBBRWdjRWN3dFJKTEQwemJIS09BWTRyYkIvelF5UnlKQ0FOR2lRQUM0Q0RLQ1I4Z3d3QXArdEZnWVFsSUR6aWdnR0NLd0FmODBDQ0tUaUVJUUFEUUFTQXd2UUFBSWdBQkFBQkFBRUVFQUFBQUVxVUFBQUFBQUFBQUFBQUE=
+    pc_init: 1
+    pc_uninit: 37
+    pc_program_page: 81
+    pc_erase_sector: 41
+    pc_erase_all: ~
+    data_section_offset: 160
+    flash_properties:
+      address_range:
+        start: 0
+        end: 1048576
+      page_size: 512
+      erased_byte_value: 255
+      program_page_timeout: 100
+      erase_sector_timeout: 1000
+      sectors:
+        - size: 8192
+          address: 0
+core: M4
\ No newline at end of file