Start implementing LCD driver
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//! Driver for LiquidCrystal Displays plugs to the GPIO of the board.
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//! The LCD need to be an Hitachi HD44780 chipset compatible.
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//!
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//! This driver inspired from the one from the arduino libriaries
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//! (https://github.com/arduino-libraries/LiquidCrystal) and the
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//! documentation from wikipedia (https://en.wikipedia.org/wiki/Hitachi_HD44780_LCD_controller)
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use crate::gpio;
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// TODO: change USIZE to a Pin struct (and implement the Pin struct :'( )
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/// The structure handling the LCD periferic
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pub struct Lcd {
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/// The Register Select pinout.
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rs_pin: usize,
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/// The Read/Write pinout.
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///
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/// If set to None, assumes the rw pin of the lcd is connected to the ground (write state)
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rw_pin: Option<usize>,
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/// The Enable pinout.
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///
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/// TODO: wiki says falling-edge triggered, arduino comment says activated by a HIGH pulse.
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e_pin: usize,
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/// First 4 data bits pins.
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///
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/// Set to None if the lcd is in 4-bit mode.
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first_data_bits_pins: Option<[usize; 4]>,
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/// Last 4 data bits pins.
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last_data_bits_pins: [usize; 4],
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/// The number of line of the LCD.
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nb_lines: usize,
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/// The number of row of the LCD.
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nb_rows: usize,
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/// Weither or not the LCD has been initialized in the rigth state.
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initialized: bool,
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}
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impl Lcd {
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/// Instanciate a [`Lcd`] object in 4 bits mode.
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pub const fn new_4bits_mode(
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rs_pin: usize,
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rw_pin: Option<usize>,
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e_pin: usize,
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db4: usize,
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db5: usize,
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db6: usize,
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db7: usize,
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nb_lines: usize,
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nb_rows: usize,
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) -> Self {
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Self {
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rs_pin,
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rw_pin,
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e_pin,
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first_data_bits_pins: None,
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last_data_bits_pins: [db4, db5, db6, db7],
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nb_lines,
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nb_rows,
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initialized: false,
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}
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}
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/// Instanciate a [`Lcd`] object in 8 bits mode.
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pub const fn new_8bits_mode(
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rs_pin: usize,
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rw_pin: Option<usize>,
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e_pin: usize,
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db0: usize,
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db1: usize,
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db2: usize,
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db3: usize,
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db4: usize,
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db5: usize,
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db6: usize,
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db7: usize,
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nb_lines: usize,
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nb_rows: usize,
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) -> Self {
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Self {
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rs_pin,
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rw_pin,
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e_pin,
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first_data_bits_pins: Some([db0, db1, db2, db3]),
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last_data_bits_pins: [db4, db5, db6, db7],
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nb_lines,
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nb_rows,
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initialized: false,
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}
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}
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/// Initialize the LCD.
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pub fn init(&mut self) -> Result::<(), &str> {
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gpio::set_pin_fonction(self.rs_pin, gpio::PinFunction::Output)?;
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gpio::set_pin_output_state(self.rs_pin, gpio::PinOutputState::Low)?;
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if let Some(rw_pin) = self.rw_pin {
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gpio::set_pin_fonction(rw_pin, gpio::PinFunction::Output)?;
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gpio::set_pin_output_state(rw_pin, gpio::PinOutputState::Low)?;
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}
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gpio::set_pin_fonction(self.e_pin, gpio::PinFunction::Output)?;
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gpio::set_pin_output_state(self.e_pin, gpio::PinOutputState::Low)?;
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if let Some(first_data_bits_pins) = self.first_data_bits_pins {
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for pin in first_data_bits_pins.into_iter() {
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gpio::set_pin_fonction(pin, gpio::PinFunction::Output)?;
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}
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}
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for pin in self.last_data_bits_pins.into_iter() {
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gpio::set_pin_fonction(pin, gpio::PinFunction::Output)?;
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}
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// TODO: send 0b0011 3 times to make sure to be in 8bits mode 5x8 characters
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// TODO: set the new mode with Function set (2 times if 4 bits modes, 1 to set DL=0,
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// then the actual one)
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self.initialized = true;
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todo!();
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}
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/// Send an 'enable' signal.
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fn enable(&self) {
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todo!()
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}
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/// Send a Function Set instruction.
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fn function_set(&self) {
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todo!()
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}
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/// Send data to the lcd.
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fn send_data(&self) {
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todo!()
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}
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/// Send 8 bits of data.
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fn send_8bit(&self) {
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todo!()
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}
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/// Send 4 bits of data.
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fn send_4bits(&self) {
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// TODO: type?
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todo!()
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}
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}
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@ -0,0 +1,3 @@
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//! Generic driver for perifierics to plug to the GPIO.
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pub mod lcd;
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