Improve M2 Bootloader LED Handling

 Added busy-wait delay for visible LED blinking
- Turn on LED at bootloader start for debugging
- Used cortex_m::asm::nop() for safer delay loops
- Improved comments and code readability
- Prepared code for future enhancements like timers and UART debug

Author: m-a-h-b-u-b

app/src/main.rs

@@ -1,24 +1,40 @@
-//! M2 Bootloader RUST 
-//! ------------------
+//! M2 Bootloader RUST APP Module
+//! ------------------------------
 //! License : Dual License
 //!           - Apache 2.0 for open-source / personal use
 //!           - Commercial license required for closed-source use
 //! Author  : Md Mahbubur Rahman
 //! URL     : <https://m-a-h-b-u-b.github.io>
-//! GitHub  : <https://github.com/m-a-h-b-u-b/M2-Bootloader-RUST>
-
+//! GitHub  : <https://github.com/m-a-h-b-u-b/M2-Bootloader-Rust>
 
 #![no_std]
 #![no_main]
 
+use cortex_m::asm;
 use cortex_m_rt::entry;
 mod peripherals;
 
+/// Entry point for the bootloader
 #[entry]
 fn main() -> ! {
+    // Initialize system peripherals (LED, timers, etc.)
     peripherals::init_led();
 
+    // Optional: indicate bootloader start
+    peripherals::led_on();
+
     loop {
+        // Toggle LED with a delay for visible blinking
         peripherals::toggle_led();
+        delay();
+    }
+}
+
+/// Simple busy-wait delay
+#[inline(always)]
+fn delay() {
+    // Adjust the count depending on the target MCU clock speed
+    for _ in 0..5_000_000 {
+        asm::nop();
     }
-}
+}