adding basic program

Cargo.lock

@@ -2,6 +2,24 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "libc"
+version = "0.2.144"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b00cc1c228a6782d0f076e7b232802e0c5689d41bb5df366f2a6b6621cfdfe1"
+
+[[package]]
+name = "rppal"
+version = "0.14.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "612e1a22e21f08a246657c6433fe52b773ae43d07c9ef88ccfc433cc8683caba"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "rust-simple-gpio"
 version = "0.1.0"
+dependencies = [
+ "rppal",
+]

Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+rppal = "0.14.1"

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(())
 }