Merge pull request #543 from stm32-rs/i2c-f4

backport I2c implementation from f4xx-hal

Author: burrbull

CHANGELOG.md

@@ -20,6 +20,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - `Spi` now takes `Option<PIN>` for `SCK`, `MISO`, `MOSI` [#514],
   add `SPIx::NoSck`, etc. [#537]
 - `spi::FrameSize` and `embedded-hal` 1.0 implementations
+- Backport `I2c` implementation from `f4xx-hal`
 - move `Qei` mod inside `pwm_input` mod [#516]
 
 ### Changed

Cargo.toml

@@ -60,6 +60,8 @@ optional = true
 panic-halt = "1.0.0"
 panic-semihosting = "0.6.0"
 panic-itm = "0.4.2"
+panic-probe = "1.0"
+rtt-target = "0.6.1"
 cortex-m-rtic = "1.1.3"
 cortex-m-semihosting = "0.5.0"
 heapless = "0.8.0"

examples/i2c_scanner.rs

@@ -0,0 +1,59 @@
+//! Example of using I2C.
+//! Scans available I2C devices on bus and print the result.
+
+#![no_std]
+#![no_main]
+
+use panic_probe as _;
+
+use rtt_target::{rprint, rprintln, rtt_init_print};
+
+use cortex_m_rt::entry;
+
+use stm32f1xx_hal::{self as hal, gpio::GpioExt, i2c::I2c, pac, prelude::*};
+
+const VALID_ADDR_RANGE: core::ops::Range<u8> = 0x08..0x78;
+
+#[entry]
+fn main() -> ! {
+    rtt_init_print!();
+    let dp = pac::Peripherals::take().unwrap();
+
+    let mut rcc = dp.RCC.constrain();
+
+    let gpiob = dp.GPIOB.split(&mut rcc);
+
+    // Configure I2C1
+    let scl = gpiob.pb6;
+    let sda = gpiob.pb7;
+    let mut i2c = I2c::new(
+        dp.I2C1,
+        (scl, sda),
+        hal::i2c::Mode::standard(100.kHz()),
+        &mut rcc,
+    );
+
+    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 {}
+}