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Cargo.toml

@@ -4,8 +4,6 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
-arduino-hal = {  git = "https://github.com/rahix/avr-hal", features = ["arduino-uno"] }
-panic-halt = "0.2.0"
 
 [profile.release]
 lto = true

src/main.rs

@@ -1,19 +1,48 @@
+#![feature(asm_experimental_arch)]
 #![no_std]
 #![no_main]
 
-use arduino_hal::delay_ms;
-use panic_halt as _;
+use core::arch::asm;
+use core::ptr::{read_volatile, write_volatile};
 
-#[arduino_hal::entry]
-fn main() -> ! {
-    let peripherals = arduino_hal::Peripherals::take().unwrap();
-    let pins = arduino_hal::pins!(peripherals);
+/*
+PORTC{0..5} Analog
+PORTC6 Reset
 
-    let mut led = pins.d13.into_output();
-    led.set_high();
+PORTB{0..5} Digital {8..13}
+PORTD{0..7} Digital {0..7}
+
+PORTB5 LED_BUILTIN
+ */
+
+const DDRB: *mut u8 = 0x24 as *mut u8;
+const PORTB: *mut u8 = 0x25 as *mut u8;
+
+// ATmega328p cycle speed
+const CPU_SPEED: u32 = 16_000_000;
+
+#[no_mangle]
+pub extern "C" fn main() -> ! {
+    // Set all the B pins on OUTPUT mode
+    unsafe { write_volatile(DDRB, 0b11111111) };
 
     loop {
-        led.toggle();
-        delay_ms(1000);
+        // if pin[5] == 1: 1^1 = 0
+        // if pin[5] == 0: 0^1 = 1
+        let mut portb_value = unsafe { read_volatile(PORTB) };
+        portb_value = portb_value ^ (1 << 5);
+        unsafe { write_volatile(PORTB, portb_value) };
+        sleep(1);
     }
 }
+
+fn sleep(time: u32) {
+    for _ in 0..(CPU_SPEED / 10 * time) {
+        unsafe { asm!("nop") }
+    }
+}
+
+#[panic_handler]
+fn panic(_info: &::core::panic::PanicInfo) -> ! {
+    loop {}
+}