add custom error type to handle results

src/error.rs

@@ -0,0 +1,16 @@
+use core::fmt::{self, Debug};
+use hal::digital::v2::OutputPin;
+
+pub enum Error<GPIO: OutputPin> {
+    /// A GPIO could not be set.
+    Gpio(GPIO::Error),
+}
+
+impl<GPIO: OutputPin> Debug for Error<GPIO>
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Error::Gpio(_) => write!(f, "GPIO error"),
+        }
+    }
+}

src/interface.rs

@@ -1,3 +1,4 @@
+use crate::Error;
 use hal;
 
 // Section 15.2 of the HINK-E0213A07 data sheet says to hold for 10ms
@@ -144,22 +145,22 @@ where
     type Error = SPI::Error;
 
     fn reset<D: hal::blocking::delay::DelayMs<u8>>(&mut self, delay: &mut D){
-        self.reset.set_low();
+        self.reset.set_low().map_err::<Error<RESET>, _>(Error::Gpio).unwrap();
         delay.delay_ms(RESET_DELAY_MS);
-        self.reset.set_high();
+        self.reset.set_high().map_err::<Error<RESET>, _>(Error::Gpio).unwrap();
         delay.delay_ms(RESET_DELAY_MS);
     }
 
     fn send_command(&mut self, command: u8) -> Result<(), Self::Error> {
-        self.dc.set_low();
+        self.dc.set_low().map_err::<Error<DC>, _>(Error::Gpio).unwrap();
         self.write(&[command])?;
-        self.dc.set_high();
+        self.dc.set_high().map_err::<Error<DC>, _>(Error::Gpio).unwrap();
 
         Ok(())
     }
 
     fn send_data(&mut self, data: &[u8]) -> Result<(), Self::Error> {
-        self.dc.set_high();
+        self.dc.set_high().map_err::<Error<DC>, _>(Error::Gpio).unwrap();
         self.write(data)
     }
 

src/lib.rs

@@ -47,12 +47,14 @@ mod color;
 pub mod command;
 pub mod config;
 pub mod display;
+pub mod error;
 pub mod graphics;
 pub mod interface;
 
 pub use color::Color;
 pub use config::Builder;
 pub use display::{Dimensions, Display, Rotation};
+pub use error::Error;
 pub use graphics::GraphicDisplay;
 pub use interface::DisplayInterface;
 pub use interface::Interface;