add gpio crate

rasynth/src/board.rs

@@ -0,0 +1,18 @@
+use std::error::Error;
+use std::thread;
+use std::time::Duration;
+
+use rppal::gpio::Gpio;
+use rppal::system::DeviceInfo;
+
+const GPIO_LED: u8 = 23; // PIN16
+
+#[test]
+fn test_gpio() -> Result<(), Box<dyn Error>> {
+    println!("Blinking an LED on a {}.", DeviceInfo::new()?.model());
+    let mut pin = Gpio::new()?.get(GPIO_LED)?.into_output();
+    pin.set_high();
+    thread::sleep(Duration::from_millis(500));
+    pin.set_low();
+    Ok(())
+}

rasynth/src/main.rs

@@ -6,6 +6,7 @@ use std::fs;
 pub mod ast;
 pub mod graph;
 pub mod symbol_table;
+pub mod board;
 
 lalrpop_mod!(pub raslisp); // synthesized by LALRPOP