rtic_blinky, add instructions to terminal based debugging

CHANGELOG.md

 # Changelog
 
+## 2021-02-23
+
+- examples/rtic_blinky.rs, added instructions to terminal based debugging
+  
 ## 2021-02-22
 
 - memory.x, reduced flash size to 128k to match light-weight target

Cargo.toml

@@ -23,7 +23,7 @@ panic-halt = "0.2.0"
 panic-rtt-target = { version = "0.1.1", features = ["cortex-m"] }
 
 # Uncomment for the semihosting examples.
-#panic-semihosting = "0.5.6"
+panic-semihosting = "0.5.6"
 
 # Tracing
 rtt-target = { version = "0.3.0", features = ["cortex-m"] }

examples/rtic_blinky.rs

+// run with gdb, either from terminal or in vscode
+//
+// from terminal:
+// start openocd in separate terminal
+// > openocd -f openocd.cfg
+//
+// start gdb
+// > arm-none-eabi-gdb target/thumbv7em-none-eabihf/debug/examples/rtic_blinky -x openocd.gdb
+
 #![deny(unsafe_code)]
 #![deny(warnings)]
 #![no_main]
@@ -5,7 +14,7 @@
 
 use cortex_m::peripheral::DWT;
 use cortex_m_semihosting::hprintln;
-use panic_rtt_target as _;
+use panic_semihosting as _;
 use rtic::cyccnt::{Instant, U32Ext as _};
 use stm32f4xx_hal::stm32;