Now the led blink

src/main.rs

@@ -1,8 +1,32 @@
+#![feature(asm_experimental_arch)]
 #![no_std]
 #![no_main]
 
+use core::arch::asm;
+use core::ptr::{read_volatile, write_volatile};
+
+const DDRB: *mut u8 = 0x24 as *mut u8;
+const PORTB: *mut u8 = 0x25 as *mut u8;
+
+const CPU_SPEED: u32 = 16_000_000;
+
 #[no_mangle]
-pub extern "C" fn main() {}
+pub extern "C" fn main() -> ! {
+    unsafe { write_volatile(DDRB, 0b11111111) };
+
+    loop {
+        unsafe { write_volatile(PORTB, 0b00000000) };
+        sleep(1);
+        unsafe { write_volatile(PORTB, 0b00100000) };
+        sleep(1);
+    }
+}
+
+fn sleep(time: u32) {
+    for _ in 0..(CPU_SPEED / 10 * time) {
+        unsafe { asm!("nop") }
+    }
+}
 
 #[panic_handler]
 fn panic(_info: &::core::panic::PanicInfo) -> ! {