Implement low level communication with LCD+begining of the init process

TODO.md

@@ -0,0 +1,4 @@
+- Implement the actual mutex
+- Implement gpio PIN struct
+- Implement singleton to protect hardware wrappers against concurent access
+- Implement Error

src/bsp/generic_gpio_drivers/lcd.rs

@@ -4,10 +4,28 @@
 //! This driver inspired from the one from the arduino libriaries
 //! (https://github.com/arduino-libraries/LiquidCrystal) and the
 //! documentation from wikipedia (https://en.wikipedia.org/wiki/Hitachi_HD44780_LCD_controller)
+//! and the actual doc (https://www.sparkfun.com/datasheets/LCD/HD44780.pdf)
 
+use crate::bsp::aarch64::time::time_manager;
 use crate::gpio;
+use crate::traits::time::TimeManager;
+use core::time::Duration;
+
+/// The font size
+pub enum FontSize {
+    Font5x8Dots,
+    Font5x10Dots,
+}
+
+impl FontSize {
+    fn function_code(&self) -> u8 {
+        match self {
+            Self::Font5x8Dots => Lcd::FUNCTION_SET_5X8_DOTS,
+            Self::Font5x10Dots => Lcd::FUNCTION_SET_5X10_DOTS,
+        }
+    }
+}
 
-// TODO: change USIZE to a Pin struct (and implement the Pin struct :'( )
 /// The structure handling the LCD periferic
 pub struct Lcd {
     /// The Register Select pinout.
@@ -35,6 +53,23 @@ pub struct Lcd {
 }
 
 impl Lcd {
+
+    /// The instruction to turn off the display
+    const INSTRUCTION_DISPLAY_OFF: u8 = 0b0000_1000;
+    /// The instruction to clear the display
+    const INSTRUCTION_DISPLAY_CLEAR: u8 = 0b0000_0001;
+
+    /// The bit indicating a function set instruction
+    const FUNCTION_SET_INDICATOR: u8 = 0b0010_0000;
+    /// The bit indicating the use of only one line
+    const FUNCTION_SET_ONE_LINE_INDICATOR: u8 = 0b0000_0000;
+    /// The bit indicating the use of only two lines
+    const FUNCTION_SET_TWO_LINES_INDICATOR: u8 = 0b0000_1000;
+    /// The bit indicating the use of the 5x8 font
+    const FUNCTION_SET_5X8_DOTS: u8 = 0b0000_0000;
+    /// The bit indicating the use of the 5x10 font
+    const FUNCTION_SET_5X10_DOTS: u8 = 0b0000_0100;
+
     /// Instanciate a [`Lcd`] object in 4 bits mode.
     pub const fn new_4bits_mode(
         rs_pin: usize,
@@ -88,7 +123,7 @@ impl Lcd {
     }
 
     /// Initialize the LCD.
-    pub fn init(&mut self) -> Result::<(), &str> {
+    pub fn init(&mut self, font_size: FontSize) -> Result<(), &'static str> {
         gpio::set_pin_fonction(self.rs_pin, gpio::PinFunction::Output)?;
         gpio::set_pin_output_state(self.rs_pin, gpio::PinOutputState::Low)?;
         if let Some(rw_pin) = self.rw_pin {
@@ -100,42 +135,128 @@ impl Lcd {
         if let Some(first_data_bits_pins) = self.first_data_bits_pins {
             for pin in first_data_bits_pins.into_iter() {
                 gpio::set_pin_fonction(pin, gpio::PinFunction::Output)?;
+                gpio::set_pin_output_state(pin, gpio::PinOutputState::Low)?;
             }
         }
         for pin in self.last_data_bits_pins.into_iter() {
             gpio::set_pin_fonction(pin, gpio::PinFunction::Output)?;
+            gpio::set_pin_output_state(pin, gpio::PinOutputState::Low)?;
         }
 
-        // TODO: send 0b0011 3 times to make sure to be in 8bits mode 5x8 characters
-        // TODO: set the new mode with Function set (2 times if 4 bits modes, 1 to set DL=0,
-        //     then the actual one)
+        let db4 = self.last_data_bits_pins[0];
+        let db5 = self.last_data_bits_pins[1];
+
+        // The initialization process as described in figure 23/24 of the doc
+        // First, wait 15 ms after poweron. To be sure, wait 30 ms
+        time_manager().sleep(Duration::from_millis(30));
+
+        // Currently the state of the lcd is undefined. We must make sur
+        // to be in 8bits mode by sendy 0b0011_0000 3 times.
+        gpio::set_pin_output_state(db4, gpio::PinOutputState::High)?;
+        gpio::set_pin_output_state(db5, gpio::PinOutputState::High)?;
+        self.pulse()?;
+        time_manager().sleep(Duration::from_micros(4100));
+        self.pulse()?;
+        time_manager().sleep(Duration::from_micros(100));
+        self.pulse()?;
+        time_manager().sleep(Duration::from_micros(100));
+        gpio::set_pin_output_state(db4, gpio::PinOutputState::Low)?;
+        gpio::set_pin_output_state(db5, gpio::PinOutputState::Low)?;
+        
+        // Now we are in 8bits mode, if we only have 4 data pins, we
+        // needs to set the mode to 4 bits.
+        if self.first_data_bits_pins.is_none() {
+            gpio::set_pin_output_state(db5, gpio::PinOutputState::High)?;
+            self.pulse()?;
+        }
+
+        let mut function = Self::FUNCTION_SET_INDICATOR;
+        if self.first_data_bits_pins.is_some() {
+            function |= 0b0001_0000;
+        }
+
+        if self.nb_lines == 1 {
+            function |= Self::FUNCTION_SET_ONE_LINE_INDICATOR;
+        } else if self.nb_lines == 2 {
+            function |= Self::FUNCTION_SET_TWO_LINES_INDICATOR;
+        } else {
+            return Err("Only 1 and 2 lines modes are supported");
+        }
+
+        function |= font_size.function_code();
+        self.send_data(function)?;
+
         self.initialized = true;
+
+        self.display_off()?;
+        self.display_clear()?;
+        // TODO: self.set_entry_mode(stuff)?;
+
         todo!();
     }
 
-    /// Send an 'enable' signal.
-    fn enable(&self) {
-        todo!()
+    /// Turn the display off.
+    pub fn display_off(&self) -> Result<(), &'static str> {
+        if self.initialized {
+            self.send_data(Self::INSTRUCTION_DISPLAY_OFF)
+        } else {
+            Err("Cannot control the LCD without initializing it first")
+        }
     }
 
-    /// Send a Function Set instruction.
-    fn function_set(&self) {
-        todo!()
+    /// Clear the display
+    pub fn display_clear(&self) -> Result<(), &'static str> {
+        if self.initialized {
+            self.send_data(Self::INSTRUCTION_DISPLAY_CLEAR)
+        } else {
+            Err("Cannot control the LCD without initializing it first")
+        }
+    }
+
+    /// Tell the LCD that the data is ready to be read.
+    fn pulse(&self) -> Result<(), &'static str> {
+        gpio::set_pin_output_state(self.e_pin, gpio::PinOutputState::Low)?;
+        time_manager().sleep(Duration::from_nanos(500));
+        gpio::set_pin_output_state(self.e_pin, gpio::PinOutputState::High)?;
+        time_manager().sleep(Duration::from_nanos(500));
+        gpio::set_pin_output_state(self.e_pin, gpio::PinOutputState::Low)?;
+        time_manager().sleep(Duration::from_micros(50));
+        Ok(())
     }
 
     /// Send data to the lcd.
-    fn send_data(&self) {
-        todo!()
+    fn send_data(&self, data: u8) -> Result<(), &'static str> {
+        if let Some(first_data_bits_pins) = self.first_data_bits_pins {
+            for (i, pin) in first_data_bits_pins.iter().enumerate() {
+                let value = Self::get_bit_value(data, i);
+                gpio::set_pin_output_state(*pin, value)?;
+            }
+            for (i, pin) in self.last_data_bits_pins.iter().enumerate() {
+                let value = Self::get_bit_value(data, i+4);
+                gpio::set_pin_output_state(*pin, value)?;
+            }
+            self.pulse()
+        } else {
+            for (i, pin) in self.last_data_bits_pins.iter().enumerate() {
+                let value = Self::get_bit_value(data, i+4);
+                gpio::set_pin_output_state(*pin, value)?;
+            }
+            self.pulse()?;
+            for (i, pin) in self.last_data_bits_pins.iter().enumerate() {
+                let value = Self::get_bit_value(data, i+4);
+                gpio::set_pin_output_state(*pin, value)?;
+            }
+            self.pulse()
+        }
     }
 
-    /// Send 8 bits of data.
-    fn send_8bit(&self) {
-        todo!()
-    }
-
-    /// Send 4 bits of data.
-    fn send_4bits(&self) {
-        // TODO: type?
-        todo!()
+    /// Return the value of the pin correponding to the bit `i` of `data`.
+    #[inline]
+    fn get_bit_value(data: u8, i: usize) -> gpio::PinOutputState {
+        if (data & (1 << i)) != 0 {
+            gpio::PinOutputState::High
+        } else {
+            gpio::PinOutputState::Low
+        }
     }
 }

src/main.rs

@@ -38,6 +38,7 @@ use crate::bsp::rpi3::gpio;
 use crate::bsp::rpi3::uart::console;
 
 use crate::bsp::generic_gpio_drivers::lcd::Lcd;
+use crate::bsp::generic_gpio_drivers::lcd;
 use crate::traits::time::TimeManager;
 
 // TODO: move this to BSP
@@ -84,7 +85,7 @@ pub unsafe fn _start_rust() -> ! {
     fatal!("fatal");
 
     let mut lcd = Lcd::new_8bits_mode(1, Some(2), 3, 4, 5, 6, 7, 8, 9, 10, 11, 1, 80);
-    let _ = lcd.init();
+    let _ = lcd.init(lcd::FontSize::Font5x8Dots);
 
     let mut buffer = ['X'; 200];
     let mut i = 0;