Implement defining custom characters

src/character.rs

@@ -0,0 +1,40 @@
+use core::iter::once;
+
+use embedded_hal::delay::DelayNs;
+
+use crate::{bus::DataBus, charset::CharsetWithFallback, error::Result, memory_map::DisplayMemoryMap, HD44780};
+
+pub struct CharacterDefinition {
+	pub pattern: [u8; 10],
+	pub cursor: u8,
+
+	// /// Since lines 12 to 16 are not used for display,
+	// /// they can be used for general data RAM.
+	// pub data: Option<[u8; 5]>,
+}
+
+impl<B, M, C> HD44780<B, M, C>
+where
+	B: DataBus,
+	M: DisplayMemoryMap,
+	C: CharsetWithFallback,
+{
+	pub fn define_custom_character<D: DelayNs>(
+		&mut self,
+		code: u8,
+		def: &CharacterDefinition,
+		delay: &mut D,
+	) -> Result<(), B::Error> {
+        self.write_command(0b01000000 | (code & 0b11) << 4, delay)?;
+        delay.delay_us(100);
+
+        let lines = def.pattern.iter().cloned().chain(once(def.cursor));
+        for line in lines {
+            self.write_byte(line, delay)?;
+        }
+
+        // Change back to DDRAM
+		self.set_cursor_pos(0, delay)?;
+		Ok(())
+	}
+}

src/lib.rs

@@ -18,6 +18,7 @@ use entry_mode::{CursorMode, EntryMode};
 
 pub mod setup;
 
+pub mod character;
 pub mod charset;
 
 pub mod memory_map;