Add I2C example

Author: Piroro-hs

Cargo.toml

@@ -134,3 +134,7 @@ required-features = ["stm32f303"]
 [[example]]
 name = "adc"
 required-features = ["stm32f303"]
+
+[[example]]
+name = "i2c_scanner"
+required-features = ["stm32f303xc"]

examples/i2c_scanner.rs

@@ -0,0 +1,61 @@
+//! Example of using I2C.
+//! Scans available I2C devices on bus and print the result.
+//! Appropriate pull-up registers should be installed on I2C bus.
+//! Target board: STM32F3DISCOVERY
+
+#![no_std]
+#![no_main]
+
+use core::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 pins = (
+        gpiob.pb6.into_af4(&mut gpiob.moder, &mut gpiob.afrl), // SCL
+        gpiob.pb7.into_af4(&mut gpiob.moder, &mut gpiob.afrl), // SDA
+    );
+    let mut i2c = hal::i2c::I2c::new(dp.I2C1, pins, 100.khz(), clocks, &mut rcc.apb1);
+
+    hprintln!("Start i2c scanning...").expect("Error using hprintln.");
+    hprintln!().unwrap();
+
+    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!().unwrap();
+    hprintln!("Done!").unwrap();
+
+    loop {
+        asm::wfi();
+    }
+}