graphics_i2c.rs

//! Draw a square, circle and triangle on the screen using the `embedded_graphics` crate.
//!
//! 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 graphics_i2c`.

#![no_std]
#![no_main]

use cortex_m_rt::{entry, exception, ExceptionFrame};
use embedded_graphics::{
    pixelcolor::BinaryColor,
    prelude::*,
    primitives::{Circle, Rectangle, Triangle},
    style::PrimitiveStyleBuilder,
};
use panic_halt as _;
use ssd1306::{prelude::*, Builder};
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 mut rcc = dp.RCC.constrain();

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

    let mut afio = dp.AFIO.constrain(&mut rcc.apb2);

    let mut gpiob = dp.GPIOB.split(&mut rcc.apb2);

    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,
        &mut rcc.apb1,
        1000,
        10,
        1000,
        1000,
    );

    let mut disp: GraphicsMode<_> = Builder::new().connect_i2c(i2c).into();

    disp.init().unwrap();

    let yoffset = 20;

    let style = PrimitiveStyleBuilder::new()
        .stroke_width(1)
        .stroke_color(BinaryColor::On)
        .build();

    // screen outline
    // default display size is 128x64 if you don't pass a _DisplaySize_
    // enum to the _Builder_ struct
    Rectangle::new(Point::new(0, 0), Point::new(127, 63))
        .into_styled(style)
        .draw(&mut disp)
        .unwrap();

    // triangle
    Triangle::new(
        Point::new(16, 16 + yoffset),
        Point::new(16 + 16, 16 + yoffset),
        Point::new(16 + 8, yoffset),
    )
    .into_styled(style)
    .draw(&mut disp)
    .unwrap();

    // square
    Rectangle::new(Point::new(52, yoffset), Point::new(52 + 16, 16 + yoffset))
        .into_styled(style)
        .draw(&mut disp)
        .unwrap();

    // circle
    Circle::new(Point::new(96, yoffset + 8), 8)
        .into_styled(style)
        .draw(&mut disp)
        .unwrap();

    disp.flush().unwrap();

    loop {}
}

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