From 50fdc339083a34d91ada1c462c67978e58f87f11 Mon Sep 17 00:00:00 2001
From: Lotte Steenbrink <lotte.steenbrink@ferrous-systems.com>
Date: Mon, 19 Apr 2021 11:21:21 +0200
Subject: [PATCH 1/4] point out parts of a embedded program in helo.rs,
 Cargo.toml

---
 beginner/apps/.cargo/config.toml |  1 +
 beginner/apps/src/bin/hello.rs   | 10 +++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/beginner/apps/.cargo/config.toml b/beginner/apps/.cargo/config.toml
index be9aeec..7a1c918 100644
--- a/beginner/apps/.cargo/config.toml
+++ b/beginner/apps/.cargo/config.toml
@@ -12,4 +12,5 @@ rustflags = [
 ]
 
 [build]
+# cross-compile to this target
 target = "thumbv7em-none-eabihf" # = ARM Cortex-M4
\ No newline at end of file
diff --git a/beginner/apps/src/bin/hello.rs b/beginner/apps/src/bin/hello.rs
index 62a8ad0..9d20aa2 100644
--- a/beginner/apps/src/bin/hello.rs
+++ b/beginner/apps/src/bin/hello.rs
@@ -1,12 +1,20 @@
-#![no_main]
+// this program does not use the standard library to avoid heap allocations.
+// only the `core` library functions are available.
 #![no_std]
+// this program uses a custom entry point instead of `fn main()`
+#![no_main]
 
 use cortex_m::asm;
 use cortex_m_rt::entry;
 use panic_log as _; // the panicking behavior
 
+
 #[entry]
+// ˆˆˆˆ the custom entry point
 fn main() -> ! {
+    //      ˆˆˆ
+    //      ! is the 'never' type: this function never returns
+
     // initializes the peripherals
     dk::init().unwrap();
 

From adaca12a61adb5d4e334b70b2096ef903af790d4 Mon Sep 17 00:00:00 2001
From: Lotte Steenbrink <lotte.steenbrink@ferrous-systems.com>
Date: Mon, 19 Apr 2021 11:55:11 +0200
Subject: [PATCH 2/4] appeal to the rustfmt gods

---
 beginner/apps/src/bin/hello.rs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/beginner/apps/src/bin/hello.rs b/beginner/apps/src/bin/hello.rs
index 9d20aa2..f7734b8 100644
--- a/beginner/apps/src/bin/hello.rs
+++ b/beginner/apps/src/bin/hello.rs
@@ -9,11 +9,12 @@ use cortex_m_rt::entry;
 use panic_log as _; // the panicking behavior
 
 
+// the custom entry point
+// vvvvv
 #[entry]
-// ˆˆˆˆ the custom entry point
 fn main() -> ! {
     //      ˆˆˆ
-    //      ! is the 'never' type: this function never returns
+    //       ! is the 'never' type: this function never returns
 
     // initializes the peripherals
     dk::init().unwrap();

From 3e54af411b1fec4e49afd07c8e55ed6140eb4ee0 Mon Sep 17 00:00:00 2001
From: Lotte Steenbrink <lotte.steenbrink@ferrous-systems.com>
Date: Mon, 19 Apr 2021 11:56:28 +0200
Subject: [PATCH 3/4] add probe-run explanation

---
 beginner/apps/.cargo/config.toml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/beginner/apps/.cargo/config.toml b/beginner/apps/.cargo/config.toml
index 7a1c918..4b518a8 100644
--- a/beginner/apps/.cargo/config.toml
+++ b/beginner/apps/.cargo/config.toml
@@ -6,6 +6,8 @@ rustflags = [
 ]
 
 [target.thumbv7em-none-eabihf]
+# set custom cargo runner to flash & run on embedded target when we call `cargo run`
+# for more information, check out https://github.com/knurling-rs/probe-run
 runner = "probe-run --chip nRF52840_xxAA"
 rustflags = [
   "-C", "link-arg=-Tlink.x",

From 49a5d9e898c367602782c663b873a5bb4b7bf431 Mon Sep 17 00:00:00 2001
From: Lotte Steenbrink <lotte.steenbrink@ferrous-systems.com>
Date: Fri, 23 Apr 2021 19:13:11 +0200
Subject: [PATCH 4/4] cargo fmt

---
 beginner/apps/src/bin/hello.rs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/beginner/apps/src/bin/hello.rs b/beginner/apps/src/bin/hello.rs
index f7734b8..8a5605d 100644
--- a/beginner/apps/src/bin/hello.rs
+++ b/beginner/apps/src/bin/hello.rs
@@ -8,7 +8,6 @@ use cortex_m::asm;
 use cortex_m_rt::entry;
 use panic_log as _; // the panicking behavior
 
-
 // the custom entry point
 // vvvvv
 #[entry]