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#![doc = include_str!("../README.md")]
#![warn(missing_docs)]
use i2c_linux::I2c;
use log::*;
use std::fs::File;
use std::io::{Error, ErrorKind, Result};
use std::path::Path;
mod font;
use crate::font::BasicFont;
/// The width of the display, in pixels
pub const OLED_WIDTH: u16 = 128;
/// The height of the display, in pixels
pub const OLED_HEIGHT: u16 = 64;
/// The I2C slave address of the display
pub const OLED_ADDRESS: u16 = 0x3c;
/// The height of a single memory page
const OLED_PAGE_HEIGHT: u16 = 8;
/// Prefix for sending a command
const COMMAND_MODE: u8 = 0x00;
/// Prefix for sending bitmap data
const DATA_MODE: u8 = 0x40;
/// Empty array for clearing screen
const EMPTY_SCREEN: [u8; (OLED_WIDTH * OLED_HEIGHT) as usize] =
[0u8; (OLED_WIDTH * OLED_HEIGHT) as usize];
/// Returned for commands and data sent to the OLED display.
pub type OledResult = Result<()>;
/// For now, images are represented as byte arrays representing 8-bit grayscale bitmaps.
/// Note that images must be exactly the size of the display
pub type Image = [u8];
/// Different addressing modes available for the display.
/// They affect how pointers are advanced after data is written.
pub enum AddressingMode {
/// Each byte (column) written advances the column pointer by one.
/// When it reaches the end of the page, the page pointer is advanced
/// by one, and the column pointer is reset to zero.
Horizontal,
/// Each byte (column) written advances the page pointer by one.
/// When it reaches the last page, the column pointer is advanced
/// by one, and the page pointer is reset to zero.
Vertical,
/// This is the default mode. Each byte (column) written advances the column
/// pointer by one. When it reaches the end of the page, the column pointer
/// is reset to zero. The page pointer does not change.
Page,
}
impl From<AddressingMode> for u8 {
fn from(mode: AddressingMode) -> u8 {
match mode {
AddressingMode::Horizontal => 0x00,
AddressingMode::Vertical => 0x01,
AddressingMode::Page => 0x02,
}
}
}
/// A command that can be sent to the OLED display
pub enum Command {
/// Sets contrast level of display, with higher number meaning higher contrast. Default is 0x7f.
SetContrast,
/// Display is based on contents of graphics RAM. (default)
ContentFollowsRam,
/// Display is all on, regardless of RAM contents.
EntireDisplayOn,
/// Sets the addressing mode to one of the [`AddressingMode`](enum.AddressingMode.html)
/// values.
SetAddressingMode,
/// Turns off the display, aka sleep mode. (default)
DisplayOff,
/// Turns on the display
DisplayOn,
/// Display is white on black, ie a 1 denotes white, 0 denotes black. (default)
NormalDisplay,
/// Display is black on white, ie a 1 denotes black, 0 denotes white.
InverseDisplay,
}
impl From<Command> for u8 {
fn from(command: Command) -> u8 {
match command {
Command::ContentFollowsRam => 0xa4,
Command::EntireDisplayOn => 0xa5,
Command::SetAddressingMode => 0x20,
Command::DisplayOff => 0xae,
Command::DisplayOn => 0xaf,
Command::NormalDisplay => 0xa6,
Command::InverseDisplay => 0xa7,
Command::SetContrast => 0x81,
}
}
}
/// Represents the NanoHat OLED device
pub struct Oled {
/// Device's I2C slave address
device: I2c<File>,
}
impl Oled {
/// Opens the device from its entry in the dev filesystem.
/// # Example:
/// ```
/// # use nanohat_oled::Oled;
/// let mut oled = Oled::from_path("/dev/i2c-0");
/// ```
pub fn from_path<P: AsRef<Path>>(path: P) -> Result<Self> {
let mut i2c = I2c::from_path(path)?;
i2c.smbus_set_slave_address(OLED_ADDRESS, false)?;
Ok(Self { device: i2c })
}
/// Initial low-level setup for the display, per SSD1306 and NanoHat OLED datasheets.
pub fn init(&mut self) -> OledResult {
self.send_command(Command::DisplayOff)?;
self.send_command(0x00)?; // Set lower column address
self.send_command(0x10)?; // Set higher column address
self.send_command(0x40)?; // Set display start line
self.send_command(0xB0)?; // Set page address
self.send_command(0x81)?; // contrast control
self.send_command(0x7f)?; // default contrast is 0x7f
self.send_command(0xa1)?; // Set segment remap
self.send_command(Command::NormalDisplay)?;
self.send_command(0xa8)?; // Multiplex ratio
self.send_command(0x3f)?; // Duty = 1/64
self.send_command(0xc8)?; // Use remapped COM scan direction
self.send_command(0xd3)?; // Set display offset
self.send_command(0x00)?; // No offset
self.send_command(0xd5)?; // Set display clock division
self.send_command(0x80)?; // divide ratio
self.send_command(0xd9)?; // Set pre-charge period
self.send_command(0xf1)?;
self.send_command(0xda)?; // Set COM pins
self.send_command(0x12)?;
self.send_command(0xdb)?; // Set vcomh deselect level
self.send_command(0x40)?;
self.send_command(0x8d)?; // Set charge pump state
self.send_command(0x14)?; // charge pump enabled
self.send_command(Command::DisplayOn)?;
self.set_addressing_mode(AddressingMode::Horizontal)?;
self.clear_display()?;
Ok(())
}
/// Sends a command or command argument to the display's command parser
pub fn send_command<B: Into<u8>>(&mut self, byte: B) -> OledResult {
self.device
.i2c_write_block_data(COMMAND_MODE, &[byte.into()])?;
Ok(())
}
/// Sends a data byte to the display RAM.
///
/// Display RAM is divided into 8-row pages. When writing bytes to display RAM,
/// values are set at the current page and column pointer location.
/// Pixels are set vertically, meaning that for a single byte,
/// the LSB will be written to the top row of the current page, and the MSB will
/// be written to the bottom row. Once the byte is written, pointers will advance,
/// depending on the [`AddressingMode`](enum.AddressingMode.html).
pub fn send_data<B: Into<u8>>(&mut self, byte: B) -> OledResult {
self.device
.i2c_write_block_data(DATA_MODE, &[byte.into()])?;
Ok(())
}
/// Sends a set of data all at once into the display RAM.
/// Data is always written in chunks of 31 bytes (plus a byte to set data mode).
/// See [`send_data()`](struct.Oled.html#method.send_data) for more details on RAM layout
pub fn send_array_data<'a, B: Into<&'a [u8]>>(&mut self, data: B) -> OledResult {
for chunk in data.into().chunks(31) {
self.device.i2c_write_block_data(DATA_MODE, chunk)?;
}
Ok(())
}
/// Sets the cursor position for writing text to display RAM.
pub fn set_text_xy(&mut self, column: u8, row: u8) -> OledResult {
self.send_command(0xb0 + row)?; // set page address
self.send_command((8 * column) & 0x0f)?; // set column low address
self.send_command(0x10 + (((8 * column) >> 4) & 0x0f))?; // set column high address
Ok(())
}
/// Completely clears the display of text and images
pub fn clear_display(&mut self) -> OledResult {
self.send_command(Command::DisplayOff)?;
self.set_text_xy(0, 0)?;
self.send_array_data(&EMPTY_SCREEN[..])?;
self.send_command(Command::DisplayOn)?;
Ok(())
}
/// Writes an image bitmap to the screen.
/// The bitmap must be the same dimensions as the display.
/// Anything greater than or equal to the `threshold` will
/// be interpreted as a `1` pixel; anything under will be
/// interpreted as a `0`.
pub fn draw_image(&mut self, image: &Image, threshold: u8) -> OledResult {
if image.len() != (OLED_HEIGHT * OLED_WIDTH) as usize {
return Err(Error::new(
ErrorKind::InvalidData,
format!("Image dimensions must be {}x{}", OLED_WIDTH, OLED_HEIGHT),
));
}
let mut write_page = [0u8; (OLED_WIDTH * OLED_HEIGHT / OLED_PAGE_HEIGHT) as usize];
for (page, page_data) in image
.chunks((OLED_WIDTH * OLED_PAGE_HEIGHT) as usize)
.enumerate()
{
for (row, row_data) in page_data.chunks(OLED_WIDTH as usize).enumerate() {
for (column, pixel) in row_data.iter().enumerate() {
let pixel = if *pixel >= threshold { 1 } else { 0 };
debug!(
"page: {}, row: {}, column: {}, write offset: {}",
page,
row,
column,
(page * OLED_WIDTH as usize) + column
);
write_page[(page * OLED_WIDTH as usize) + column] |= pixel << row;
}
}
}
self.set_text_xy(0, 0)?;
self.send_array_data(&write_page[..])?;
Ok(())
}
/// Writes a single character to the display at the current
/// X,Y location (as set by [`set_text_xy()`](struct.Oled.html#method.set_text_xy)
/// and incremented by the [`AddressingMode`](enum.AddressingMode.html)).
/// Note: only printable ASCII is supported. Other characters will output as
/// an empty square.
pub fn put_char(&mut self, char: char) -> OledResult {
let bitmap = BasicFont::bitmap(char);
self.send_array_data(&bitmap[..])?;
Ok(())
}
/// Writes a string to the display, starting at the current
/// X, Y location (as set by `set_text_xy` and incremented by
/// the [`AddressingMode`](enum.AddressingMode.html)).
/// None: only printable ASCII is supported
pub fn put_string(&mut self, string: &str) -> OledResult {
for char in string.chars() {
self.put_char(char)?;
}
Ok(())
}
/// Sets the addressing mode to the supplied [`AddressingMode`](enum.AddressingMode.html).
/// See [`AddressingMode`](enum.AddressingMode.html) for more details.
/// Default is [`AddressingMode::Horizontal`](enum.AddressingMode.html#variant.Horizontal).
pub fn set_addressing_mode(&mut self, mode: AddressingMode) -> OledResult {
self.send_command(Command::SetAddressingMode)?;
self.send_command(mode)?;
Ok(())
}
}