Added an example with ITM logging

.gitignore

 target
 .gdb_history
+itm.fifo

blinky-itm/.cargo/config

+[target.thumbv7em-none-eabi]
+runner = 'arm-none-eabi-gdb'
+rustflags = [
+#  "-C", "linker=arm-none-eabi-gcc",
+#  "-C", "link-arg=-Wl,-Tlink.x",
+#  "-C", "link-arg=-nostartfiles"
+  "-C", "link-arg=-Tlink.x"
+]
+[build]
+target = "thumbv7em-none-eabi"

blinky-itm/.gdbinit

+target remote :3333
+
+# print demangled symbols by default
+set print asm-demangle on
+
+#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.fifo uart off 168000000
+
+# # OR: make the microcontroller SWO pin output compatible with UART (8N1)
+# # 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
+step

blinky-itm/Cargo.lock

+[[package]]
+name = "aligned"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "bare-metal"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "blinky-itm"
+version = "0.0.1"
+dependencies = [
+ "cast 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cortex-m 0.5.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cortex-m-rt 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "embedded-hal 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "panic-abort 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "stm32f407g-disc 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
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+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
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+version = "0.5.7"
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+ "volatile-register 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
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+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cortex-m-rt-macros 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "r0 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
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+ "syn 0.15.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
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+name = "embedded-hal"
+version = "0.2.1"
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+dependencies = [
+ "nb 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "nb"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
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+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
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+ "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
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+
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+ "proc-macro2 0.4.19 (registry+https://github.com/rust-lang/crates.io-index)",
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+
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+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
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+name = "rand"
+version = "0.5.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "rand_core 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
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+name = "rand_core"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "stm32f4"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
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+ "bare-metal 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
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+ "stm32f4xx-hal 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
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+ "embedded-hal 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "nb 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "stm32f4 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
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+
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+
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+
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "volatile-register"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "vcell 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
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+
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blinky-itm/Cargo.toml

+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g. crates.io) dependencies
+#
+# If you believe there's an error in this file please file an
+# issue against the rust-lang/cargo repository. If you're
+# editing this file be aware that the upstream Cargo.toml
+# will likely look very different (and much more reasonable)
+
+[package]
+name = "blinky-itm"
+version = "0.0.1"
+authors = ["Tim Docker<tim@dockerz.net>"]
+description = "A flashing light"
+keywords = ["arm", "cortex-m"]
+categories = ["embedded", "no-std"]
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/timbod7/..."
+
+[dependencies.cast]
+version = "0.2.2"
+default-features = false
+
+[dependencies.stm32f407g-disc]
+version = "0.1.0"
+
+[dependencies.embedded-hal]
+version = "0.2.1"
+
+[dependencies.cortex-m]
+version = "0.5.7"
+
+[dependencies.cortex-m-rt]
+version = "0.6.4"
+
+[dependencies.panic-abort]
+version = "0.3.1"

blinky-itm/README.md

+Run the binary on the stm32f407 discovery board as per normal. With
+the gdb configuration as in this directory, an itm.fifo file will be
+written.
+
+Run this command:
+
+```
+itmdump -F -f itm.fifo
+```
+
+to follow it.

blinky-itm/build.rs

+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+fn main() {
+    // Put the linker script somewhere the linker can find it
+    let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    File::create(out.join("memory.x"))
+        .unwrap()
+        .write_all(include_bytes!("memory.x"))
+        .unwrap();
+    println!("cargo:rustc-link-search={}", out.display());
+
+    // Only re-run the build script when memory.x is changed,
+    // instead of when any part of the source code changes.
+    println!("cargo:rerun-if-changed=memory.x");
+}

blinky-itm/memory.x

+MEMORY
+{
+  /* NOTE K = KiBi = 1024 bytes */
+  FLASH : ORIGIN = 0x08000000, LENGTH = 256K
+  RAM : ORIGIN = 0x20000000, LENGTH = 40K
+}
+
+/* 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; */
+
+/* Size of the heap (in bytes) */
+/* _heap_size = 1024; */

blinky-itm/src/main.rs

+#![no_main]
+#![no_std]
+
+extern crate cortex_m;
+extern crate cortex_m_rt;
+extern crate panic_abort;
+
+extern crate stm32f407g_disc as board;
+extern crate embedded_hal as hal;
+
+use cortex_m_rt::entry;
+
+use board::hal::delay::Delay;
+use board::hal::prelude::*;
+use board::hal::stm32;
+use board::gpio;
+use board::gpio::gpiod::{PD12, PD13, PD14, PD15};
+
+use hal::digital::OutputPin;
+
+use cortex_m::iprintln;
+use cortex_m::peripheral::Peripherals;
+
+struct Leds {
+   green:  PD12<gpio::Output<gpio::PushPull>>,
+   orange: PD13<gpio::Output<gpio::PushPull>>,
+   red:    PD14<gpio::Output<gpio::PushPull>>,
+   blue:   PD15<gpio::Output<gpio::PushPull>>,
+}
+
+#[entry]
+fn main() -> ! {
+    if let (Some(p), Some(cp)) = (stm32::Peripherals::take(), Peripherals::take()) {
+        let gpiod = p.GPIOD.split();
+        let mut itm = cp.ITM;
+
+        // Configure LED outputs  
+        let mut leds = Leds {
+          green: gpiod.pd12.into_push_pull_output(),
+          orange: gpiod.pd13.into_push_pull_output(),
+          red: gpiod.pd14.into_push_pull_output(),
+          blue: gpiod.pd15.into_push_pull_output(),
+        };
+
+        // Constrain clock registers
+        let mut rcc = p.RCC.constrain();
+
+        // Configure clock to 168 MHz (i.e. the maximum) and freeze it
+        let clocks = rcc.cfgr.sysclk(168.mhz()).freeze();
+
+        // Get delay provider
+        let mut delay = Delay::new(cp.SYST, clocks);
+
+        iprintln!(&mut itm.stim[0], "start" );
+
+        loop {
+            // Turn LED on
+            leds.red.set_high();
+            iprintln!(&mut itm.stim[0], "on" );
+
+            // Delay twice for half a second due to limited timer resolution
+            delay.delay_ms(500_u16);
+            delay.delay_ms(500_u16);
+
+            // Turn LED off
+            leds.red.set_low();
+            iprintln!(&mut itm.stim[0], "off" );
+
+            // Delay twice for half a second due to limited timer resolution
+            delay.delay_ms(500_u16);
+            delay.delay_ms(500_u16);
+        }
+    }
+
+    loop {}
+}
\ No newline at end of file