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//! The display driver and Frame trait. use crate::control::DisplayControl; use crate::timer::DisplayTimer; use crate::render::{Render, BRIGHTNESSES, MAX_BRIGHTNESS}; /// A set of matrix column indices. /// /// Supports maximum index 15. #[derive(Copy, Clone, Debug)] struct ColumnSet (u16); impl ColumnSet { /// Returns a new empty set. const fn empty() -> ColumnSet { ColumnSet(0) } /// Adds column index 'col' to the set. fn set(&mut self, col: usize) { self.0 |= 1<<col; } /// Returns the set as a bitmap in a u32 (LSB is index 0). fn as_u32(&self) -> u32 { self.0 as u32 } /// Says whether the set is empty. fn is_empty(&self) -> bool { self.0 == 0 } } /// A 'compiled' representation of the part of an image displayed on a single /// matrix row. /// /// RowPlans are created and contained by [`Frame`]s. // This is effectively a map brightness -> set of columns #[derive(Copy, Clone, Debug)] pub struct RowPlan ( [ColumnSet; BRIGHTNESSES], ); impl RowPlan { /// Returns a new RowPlan with all LEDs brightness 0. pub const fn default() -> RowPlan { RowPlan([ColumnSet::empty(); BRIGHTNESSES]) } /// Resets all LEDs to brightness 0. fn clear(&mut self) { self.0 = RowPlan::default().0; } /// Says which LEDs have the specified brightness. fn lit_cols(&self, brightness: u8) -> ColumnSet { self.0[brightness as usize] } /// Sets a single LED to the specified brightness. fn light_col(&mut self, brightness: u8, col: usize) { self.0[brightness as usize].set(col); } } /// Description of a device's LED layout. /// /// This describes the correspondence between the visible layout of LEDs and /// the pins controlling them. /// /// # Example implementation /// /// ``` /// # use tiny_led_matrix::Matrix; /// struct SimpleMatrix (); /// /// impl Matrix for SimpleMatrix { /// const MATRIX_COLS: usize = 2; /// const MATRIX_ROWS: usize = 3; /// const IMAGE_COLS: usize = 3; /// const IMAGE_ROWS: usize = 2; /// fn image_coordinates(col: usize, row: usize) -> Option<(usize, usize)> { /// Some((row, col)) /// } /// } /// ``` pub trait Matrix { /// The number of pins connected to LED columns. /// /// At present this can be at most 16. const MATRIX_COLS: usize; /// The number of pins connected to LED rows. /// /// This should normally be a small number (eg 3). const MATRIX_ROWS: usize; // Note that nothing uses IMAGE_COLS and IMAGE_ROWS directly; having these // constants allows us to document them. /// The number of visible LED columns. const IMAGE_COLS: usize; /// The number of visible LED rows. const IMAGE_ROWS: usize; /// Returns the image coordinates (x, y) to use for the LED at (col, row). /// /// Returns None if (col, row) doesn't control an LED. /// /// Otherwise the return value is in (0..IMAGE_COLS, 0..IMAGE_ROWS), with /// (0, 0) representing the top left. /// /// # Panics /// /// Panics if the provided col and row are out of range 0..MATRIX_COLS and /// 0..MATRIX_ROWS. fn image_coordinates(col: usize, row: usize) -> Option<(usize, usize)>; } /// A 'Compiled' representation of an image to be displayed. /// /// `Frame`s are populated from images implementing [`Render`], then passed on /// to [`Display::set_frame()`]. /// /// # Implementing `Frame` /// /// Implementations of `Frame` do two things: /// /// - specify the [`Matrix`] used to convert between image and matrix /// coordinates /// - act like an array of [`RowPlan`]s, one for each matrix row. /// /// Note that implementations of `Frame` must also implement `Copy` and /// `Default`. /// /// # Example implementation /// /// ``` /// # use tiny_led_matrix::{Matrix,Frame,RowPlan}; /// # struct SimpleMatrix (); /// # impl Matrix for SimpleMatrix { /// # const MATRIX_COLS: usize = 2; /// # const MATRIX_ROWS: usize = 3; /// # const IMAGE_COLS: usize = 3; /// # const IMAGE_ROWS: usize = 2; /// # fn image_coordinates(col: usize, row: usize) -> /// # Option<(usize, usize)> { /// # Some((row, col)) /// # } /// # } /// # /// #[derive(Copy, Clone)] /// struct SimpleFrame ( /// [RowPlan; 3] /// ); /// /// impl Default for SimpleFrame { /// fn default() -> SimpleFrame { /// SimpleFrame([RowPlan::default(); SimpleFrame::ROWS]) /// } /// } /// /// impl Frame for SimpleFrame { /// type Mtx = SimpleMatrix; /// /// fn row_plan(&self, row: usize) -> &RowPlan { /// &self.0[row] /// } /// /// fn row_plan_mut(&mut self, row: usize) -> &mut RowPlan { /// &mut self.0[row] /// } /// } /// ``` pub trait Frame: Copy + Default { /// The Matrix used to convert between image and matrix coordinates. type Mtx: Matrix; /// The number of pins connected to LED columns. const COLS: usize = Self::Mtx::MATRIX_COLS; /// The number of pins connected to LED rows. const ROWS: usize = Self::Mtx::MATRIX_ROWS; /// Returns a reference to the RowPlan for a row of LEDs. /// /// # Panics /// /// Panics if `row` is not in the range 0..ROWS fn row_plan(&self, row: usize) -> &RowPlan; /// Returns a mutable reference to the RowPlan for a row of LEDs. /// /// # Panics /// /// Panics if `row` is not in the range 0..ROWS fn row_plan_mut(&mut self, row: usize) -> &mut RowPlan; /// Stores a new image into the frame. /// /// Example: /// /// ```ignore /// frame.set(GreyscaleImage::blank()); /// ``` fn set<T>(&mut self, image: &T) where T: Render + ?Sized { for row in 0..Self::ROWS { let plan = self.row_plan_mut(row); plan.clear(); for col in 0..Self::COLS { if let Some((x, y)) = Self::Mtx::image_coordinates(col, row) { let brightness = image.brightness_at(x, y); plan.light_col(brightness, col); } } } } } // With a 16µs period, 375 ticks is 6ms const CYCLE_TICKS: u16 = 375; const GREYSCALE_TIMINGS: [u16; BRIGHTNESSES-2] = [ // Delay, Bright, Ticks, Duration, Relative power // 375, // 0, 0, 0µs, --- 373, // 1, 2, 32µs, inf 371, // 2, 4, 64µs, 200% 367, // 3, 8, 128µs, 200% 360, // 4, 15, 240µs, 187% 347, // 5, 28, 448µs, 187% 322, // 6, 53, 848µs, 189% 273, // 7, 102, 1632µs, 192% 176, // 8, 199, 3184µs, 195% // 0, // 9, 375, 6000µs, 188% ]; /// The reason for a display-timer interrupt. /// /// This is the return value from [`handle_event()`]. /// /// [`handle_event()`]: Display::handle_event #[derive(PartialEq, Eq, Debug)] pub enum Event { /// The display has switched to lighting a new row. SwitchedRow, /// The display has changed the LEDs in the current row. UpdatedRow, /// Neither a new primary cycle nor a secondary alarm has occurred. Unknown, } impl Event { /// Checks whether this event is `SwitchedRow`. /// /// This is provided for convenience in the common case where you want to /// perform some action based on the display timer's primary cycle. pub fn is_new_row(self) -> bool { self == Event::SwitchedRow } } /// Starts the timer you plan to use with a [`Display`]. /// /// Call this once before using a [`Display`]. /// /// This calls the timer's /// [`initialise_cycle()`][DisplayTimer::initialise_cycle] implementation. pub fn initialise_timer(timer: &mut impl DisplayTimer) { timer.initialise_cycle(CYCLE_TICKS); } /// Initialises the display hardware you plan to use with a [`Display`]. /// /// Call this once before using a [`Display`]. /// /// This calls the [`DisplayControl`]'s /// [`initialise_for_display()`][DisplayControl::initialise_for_display] /// implementation. pub fn initialise_control(control: &mut impl DisplayControl) { control.initialise_for_display(); } /// Manages a small LED display. /// /// There should normally be a single `Display` instance for a single piece of /// display hardware. /// /// Display is generic over a [`Frame`] type, which holds image data suitable /// for display on a particular piece of hardware. /// /// Call [`initialise_control()`] and [`initialise_timer()`] before using a /// `Display`. /// /// # Example /// /// Using `cortex-m-rtfm` v0.4.1: /// ```ignore /// #[app(device = nrf51)] /// const APP: () = { /// static mut GPIO: nrf51::GPIO = (); /// static mut TIMER1: nrf51::TIMER1 = (); /// static mut DISPLAY: Display<MyFrame> = (); /// /// #[init] /// fn init() -> init::LateResources { /// let mut p: nrf51::Peripherals = device; /// display::initialise_control(&mut MyDisplayControl(&mut p.GPIO)); /// display::initialise_timer(&mut MyDisplayTimer(&mut p.TIMER1)); /// init::LateResources { /// GPIO : p.GPIO, /// TIMER1 : p.TIMER1, /// DISPLAY : Display::new(), /// } /// } /// } /// ``` pub struct Display<F: Frame> { // index (0..F::ROWS) of the row being displayed row_strobe : usize, // brightness level (0..=MAX_BRIGHTNESS) to process next next_brightness : u8, frame : F, current_plan : RowPlan } impl<F: Frame> Display<F> { /// Creates a Display instance, initially holding a blank image. pub fn new() -> Display<F> { Display { row_strobe: 0, next_brightness: 0, frame: F::default(), current_plan: RowPlan::default(), } } /// Accepts a new image to be displayed. /// /// The code that calls this method must not be interrupting, or /// interruptable by, [`handle_event()`][Display::handle_event]. /// /// After calling this, it's safe to modify the frame again (its data is /// copied into the `Display`). /// /// # Example /// /// In the style of `cortex-m-rtfm` v0.4: /// /// ```ignore /// #[interrupt(priority = 1, resources = [RTC0, DISPLAY])] /// fn RTC0() { /// static mut FRAME: MyFrame = MyFrame::const_default(); /// let event_reg = &resources.RTC0.events_tick; /// event_reg.write(|w| unsafe {w.bits(0)} ); /// FRAME.set(GreyscaleImage::blank()); /// resources.DISPLAY.lock(|display| { /// display.set_frame(FRAME); /// }); /// } /// ``` pub fn set_frame(&mut self, frame: &F) { self.frame = *frame; } /// Updates the display for the start of a new primary cycle. /// /// Leaves the timer's secondary alarm enabled iff there are any /// intermediate brightnesses in the current image. fn render_row(&mut self, control: &mut impl DisplayControl, timer: &mut impl DisplayTimer) { assert! (self.row_strobe < F::ROWS); self.row_strobe += 1; if self.row_strobe == F::ROWS {self.row_strobe = 0}; let plan = self.frame.row_plan(self.row_strobe); let lit_cols = plan.lit_cols(MAX_BRIGHTNESS); control.display_row_leds(self.row_strobe, lit_cols.as_u32()); // We copy this so that we'll continue using it for the rest of this // 'tick' even if set_frame() is called part way through self.current_plan = *plan; self.next_brightness = MAX_BRIGHTNESS; self.program_next_brightness(timer); if self.next_brightness != 0 { timer.enable_secondary(); } } /// Updates the display to represent an intermediate brightness. /// /// This is called after an interrupt from the secondary alarm. fn render_subrow(&mut self, control: &mut impl DisplayControl, timer: &mut impl DisplayTimer) { // When this method is called, next_brightness is an intermediate // brightness in the range 1..8 (the one that it's time to display). let additional_cols = self.current_plan.lit_cols(self.next_brightness); control.light_current_row_leds(additional_cols.as_u32()); self.program_next_brightness(timer); } /// Updates next_brightness to the next (dimmer) brightness that needs /// displaying, and program the timer's secondary alarm correspondingly. /// /// If no further brightness needs displaying for this row, this means /// disabling the secondary alarm. fn program_next_brightness(&mut self, timer: &mut impl DisplayTimer) { loop { self.next_brightness -= 1; if self.next_brightness == 0 { timer.disable_secondary(); break; } if !self.current_plan.lit_cols(self.next_brightness).is_empty() { timer.program_secondary( GREYSCALE_TIMINGS[(self.next_brightness-1) as usize] ); break; } } } /// Updates the LEDs and timer state during a timer interrupt. /// /// You should call this each time the timer's interrupt is signalled. /// /// The `timer` parameter must represent the same device each time you /// call this method, and the same as originally passed to /// [`initialise_timer()`]. /// /// The `control` parameter must represent the same device each time you /// call this method, and the same as originally passed to /// [`initialise_control()`]. /// /// This method always calls the timer's /// [`check_primary()`][DisplayTimer::check_primary] and /// [`check_secondary()`][DisplayTimer::check_secondary] methods. /// /// As well as updating the LED state by calling [`DisplayControl`] /// methods, it may update the timer state by calling the timer's /// [`program_secondary()`][DisplayTimer::program_secondary], /// [`enable_secondary()`][DisplayTimer::enable_secondary], and/or /// [`disable_secondary()`][DisplayTimer::disable_secondary] methods. /// /// Returns a value indicating the reason for the interrupt. You can check /// this if you wish to perform some other action once per primary cycle. /// /// # Example /// /// In the style of `cortex-m-rtfm` v0.4: /// /// ```ignore /// #[interrupt(priority = 2, resources = [TIMER1, GPIO, DISPLAY])] /// fn TIMER1() { /// let display_event = resources.DISPLAY.handle_event( /// &mut MyDisplayControl(&mut resources.TIMER1), /// &mut MyDisplayControl(&mut resources.GPIO), /// ); /// if display_event.is_new_row() { /// ... /// } /// } /// ``` pub fn handle_event(&mut self, timer: &mut impl DisplayTimer, control: &mut impl DisplayControl) -> Event { let row_timer_fired = timer.check_primary(); let brightness_timer_fired = timer.check_secondary(); if row_timer_fired { self.render_row(control, timer); Event::SwitchedRow } else if brightness_timer_fired { self.render_subrow(control, timer); Event::UpdatedRow } else { Event::Unknown } } }