adding basic program

src/main.rs

@@ -1,6 +1,47 @@
-fn main() {
-    println!("Hello, world!");
+use std::thread;
 
-    let x = 5;
-    println!("The value of x is: {}", x);
+use rppal::gpio::{Gpio, Level, Pin};
+
+const BUTTON_PIN: u8 = 17;
+
+// with internal pull up resistor, we get a low reading as
+// the electrons flow to ground due to the voltage difference and less resistance path.
+// so the mcu reads low when the button is pressed.
+fn is_button_pressed(pin: &rppal::gpio::InputPin) -> bool {
+    pin.is_low()
+}
+
+fn is_button_pressed2(pin: &rppal::gpio::InputPin) -> bool {
+    match pin.read() {
+        Ok(Level::Low) => true,
+        Ok(Level::High) => false,
+        Err(_) => {
+            println!("Error reading pin");
+            false
+        },
+    }
+}
+
+fn read_loop(pin: &rppal::gpio::InputPin) {
+    loop {
+        if is_button_pressed(pin) {
+            println!("Button is pressed mate!");
+        }
+
+        thread::sleep(Duration::from_secs(1));
+    }
+}
+
+fn main() -> Result<(), rppal::gpio::Error> {
+    println!("Hello world");
+
+    let gpio = Gpio::new()?;
+    let pin = gpio.get(BUTTON_PIN)?.into_input_pullup();
+
+    // spawn a thread to read the pin
+    thread::spawn(|| {
+        read_loop(&pin);
+    });
+
+    Ok(())
 }