noise_i2c.rs

//! Send random raw data to the display, emulating an old untuned TV. This example `release()`s the
//! underlying display properties struct and allows calling of the low-level `draw()` method,
//! sending a 1024 byte buffer straight to the display.
//!
//! 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 noise_i2c`. Best results when using `--release`.

#![no_std]
#![no_main]

use cortex_m_rt::{entry, exception, ExceptionFrame};
use panic_halt as _;
use rand::prelude::*;
use ssd1306::{mode::displaymode::DisplayModeTrait, 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 mut props = disp.release();

    let mut buf = [0x00u8; 1024];

    let mut rng = SmallRng::seed_from_u64(0xdead_beef_cafe_d00d);

    loop {
        rng.fill_bytes(&mut buf);

        props.draw(&buf).unwrap();
    }
}

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