//! Example of using I2C.
//! Scans available I2C devices on bus and print the result.

#![no_std]
#![no_main]

use core::ops::Range;

use rtt_target::{rprint, rprintln, rtt_init_print};

use cortex_m_rt::entry;

use stm32f4xx_hal::{self as hal, gpio::GpioExt, i2c::I2c, pac, prelude::*};

const VALID_ADDR_RANGE: Range<u8> = 0x08..0x78;

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

    let rcc = dp.RCC.constrain();
    let clocks = rcc.cfgr.freeze();

    let gpiob = dp.GPIOB.split();

    // Configure I2C1
    let scl = gpiob.pb8;
    let sda = gpiob.pb7;
    let mut i2c = I2c::new(
        dp.I2C1,
        (scl, sda),
        hal::i2c::Mode::standard(100.kHz()),
        &clocks,
    );

    rprintln!("Start i2c scanning...");
    rprintln!();

    for addr in 0x00_u8..0x80 {
        // Write the empty array and check the slave response.
        let byte: [u8; 1] = [0; 1];
        if VALID_ADDR_RANGE.contains(&addr) && i2c.write(addr, &byte).is_ok() {
            rprint!("{:02x}", addr);
        } else {
            rprint!("..");
        }
        if addr % 0x10 == 0x0F {
            rprintln!();
        } else {
            rprint!(" ");
        }
    }

    rprintln!();
    rprintln!("Done!");

    #[allow(clippy::empty_loop)]
    loop {}
}

use core::panic::PanicInfo;
#[inline(never)]
#[panic_handler]
fn panic(info: &PanicInfo) -> ! {
    rprintln!("{}", info);
    loop {} // You might need a compiler fence in here.
}