stm32g0: add i2c_async example

This example will help those having difficulties understanding how to
bind interrupts on stm32g0 devices.

examples/stm32g0/src/bin/i2c_async.rs

@@ -0,0 +1,48 @@
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::i2c::{self, I2c};
+use embassy_stm32::time::Hertz;
+use embassy_stm32::{bind_interrupts, peripherals};
+use embassy_time::{Duration, Timer};
+use {defmt_rtt as _, panic_probe as _};
+
+bind_interrupts!(struct Irqs {
+    I2C1 => i2c::EventInterruptHandler<peripherals::I2C1>, i2c::ErrorInterruptHandler<peripherals::I2C1>;
+});
+
+const TMP117_ADDR: u8 = 0x48;
+const TMP117_TEMP_RESULT: u8 = 0x00;
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    info!("Hello world");
+
+    let p = embassy_stm32::init(Default::default());
+
+    let mut data = [0u8; 2];
+    let mut i2c = I2c::new(
+        p.I2C1,
+        p.PB8,
+        p.PB9,
+        Irqs,
+        p.DMA1_CH1,
+        p.DMA1_CH2,
+        Hertz(100_000),
+        Default::default(),
+    );
+
+    loop {
+        match i2c.write_read(TMP117_ADDR, &[TMP117_TEMP_RESULT], &mut data).await {
+            Ok(()) => {
+                let temp = f32::from(i16::from_be_bytes(data)) * 7.8125 / 1000.0;
+                info!("Temperature {}", temp);
+            }
+            Err(_) => error!("I2C Error"),
+        }
+
+        Timer::after(Duration::from_millis(1000)).await;
+    }
+}