text_i2c.rs

//! Print "Hello world!" with "Hello rust!" underneath. Uses the `embedded_graphics` crate to draw
//! the text with a 6x10 pixel font.
//!
//! This example is for the STM32F103 "Blue Pill" board using I2C1.
//!
//! Wiring connections are as follows for a CRIUS-branded display:
//!
//! ```
//!      Display -> Blue Pill
//! (black)  GND -> GND
//! (red)    +5V -> VCC
//! (yellow) SDA -> PB9
//! (green)  SCL -> PB8
//! ```
//!
//! Run on a Blue Pill with `cargo run --example text_i2c`.

#![no_std]
#![no_main]

use cortex_m_rt::{entry, exception, ExceptionFrame};
use embedded_graphics::{
    mono_font::{ascii::FONT_6X10, MonoTextStyleBuilder},
    pixelcolor::BinaryColor,
    prelude::*,
    text::{Baseline, Text},
};
use panic_halt as _;
use ssd1306::{prelude::*, I2CDisplayInterface, Ssd1306};
use stm32f1xx_hal::{
    i2c::{BlockingI2c, DutyCycle, Mode},
    prelude::*,
    stm32,
};

#[entry]
fn main() -> ! {
    let dp = stm32::Peripherals::take().unwrap();

    let mut flash = dp.FLASH.constrain();
    let rcc = dp.RCC.constrain();

    let clocks = rcc.cfgr.freeze(&mut flash.acr);

    let mut afio = dp.AFIO.constrain();

    let mut gpiob = dp.GPIOB.split();

    let scl = gpiob.pb8.into_alternate_open_drain(&mut gpiob.crh);
    let sda = gpiob.pb9.into_alternate_open_drain(&mut gpiob.crh);

    let i2c = BlockingI2c::i2c1(
        dp.I2C1,
        (scl, sda),
        &mut afio.mapr,
        Mode::Fast {
            frequency: 400_000.Hz(),
            duty_cycle: DutyCycle::Ratio2to1,
        },
        clocks,
        1000,
        10,
        1000,
        1000,
    );

    let interface = I2CDisplayInterface::new(i2c);
    let mut display = Ssd1306::new(interface, DisplaySize128x64, DisplayRotation::Rotate0)
        .into_buffered_graphics_mode();
    display.init().unwrap();

    let text_style = MonoTextStyleBuilder::new()
        .font(&FONT_6X10)
        .text_color(BinaryColor::On)
        .build();

    Text::with_baseline("Hello world!", Point::zero(), text_style, Baseline::Top)
        .draw(&mut display)
        .unwrap();

    Text::with_baseline("Hello Rust!", Point::new(0, 16), text_style, Baseline::Top)
        .draw(&mut display)
        .unwrap();

    display.flush().unwrap();

    loop {}
}

#[exception]
unsafe fn HardFault(ef: &ExceptionFrame) -> ! {
    panic!("{:#?}", ef);
}