Started writing documentation

src/lib.rs

@@ -1,5 +1,10 @@
 #![no_std]
 
+//! This library is an embedded-hal based driver implementation for the GDEQ031T10 e-paper display.
+//! 
+//! **Note**: 9-bit SPI mode (where the data/command is designated with an extra bit for each byte)
+//! is not supported by this driver. Only the mode with a dedicated data/command line is supported.
+
 use embedded_hal::{
     delay::DelayNs,
     digital::{InputPin, OutputPin},
@@ -10,6 +15,7 @@ const EPD_WIDTH: usize = 240;
 const EPD_HEIGHT: usize = 320;
 const EPD_ARRAY: usize = EPD_WIDTH * EPD_HEIGHT / 8;
 
+/// The display driver for the GDEQ031T10 e-paper display.
 pub struct EPaperDisplay<BusyPin, ResetPin, DcPin, SpiDevice, Delay> {
     busy: BusyPin,
     reset: ResetPin,
@@ -18,13 +24,25 @@ pub struct EPaperDisplay<BusyPin, ResetPin, DcPin, SpiDevice, Delay> {
     delay: Delay,
 }
 
+/// An error that may occur during display initialisation.
 pub enum InitError<ResetError, DcError, SpiError> {
+    /// This variant is for any error with setting the level of the reset pin.
+    /// 
+    /// This variant may be uninhabited if the `ResetPin` type parameter for [EPaperDisplay] is one that
+    /// doesn't produce errors.
     ResetError(ResetError),
+    /// This variant is for errors when attempting to communicate with the display controller after reset.
     WriteError(WriteError<DcError, SpiError>),
 }
 
+/// An error when trying to communicate with the display controller.
 pub enum WriteError<DcError, SpiError> {
+    /// This variant is for any error with setting the level of the DC (Data/Command) pin.
+    /// 
+    /// This variant may be uninhabited if the `DcPin` type parameter for [EPaperDisplay] is one that
+    /// doesn't produce errors.
     DcError(DcError),
+    /// This variant is for errors produced by the SPI driver.
     SpiError(SpiError),
 }