i2c_scanner.rs

//! Example of using I2C.
//! Scans available I2C devices on bus and print the result.
//! Target board: STM32F3DISCOVERY

#![no_std]
#![no_main]

use core::{convert::TryInto, ops::Range};

use panic_semihosting as _;

use cortex_m::asm;
use cortex_m_rt::entry;
use cortex_m_semihosting::{hprint, hprintln};

use stm32f3xx_hal::{self as hal, pac, prelude::*};

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

#[entry]
fn main() -> ! {
    let dp = pac::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 gpiob = dp.GPIOB.split(&mut rcc.ahb);

    // Configure I2C1
    let mut scl =
        gpiob
            .pb6
            .into_af_open_drain(&mut gpiob.moder, &mut gpiob.otyper, &mut gpiob.afrl);
    let mut sda =
        gpiob
            .pb7
            .into_af_open_drain(&mut gpiob.moder, &mut gpiob.otyper, &mut gpiob.afrl);
    scl.internal_pull_up(&mut gpiob.pupdr, true);
    sda.internal_pull_up(&mut gpiob.pupdr, true);
    let mut i2c = hal::i2c::I2c::new(
        dp.I2C1,
        (scl, sda),
        100.kHz().try_into().unwrap(),
        clocks,
        &mut rcc.apb1,
    );

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

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

    hprintln!();
    hprintln!("Done!");

    loop {
        asm::wfi();
    }
}