debug example

examples/hello_debug.rs

+//! Using cortex-m-debug, for simple tracing
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_std]
+
+extern crate stm32f4x_hal;
+
+// Convenient tracing over semihosting and ITM
+#[macro_use]
+extern crate cortex_m_debug;
+
+fn main() {
+    ip!("ITM: Hello ");
+    ipln!("World! for the {} time", 50);
+
+    sp!("Semihosting: Hello ");
+    spln!("World! for the {} time", 50);
+}