Merge #214

214: add USART example r=therealprof a=nebelgrau77



Co-authored-by: Daniel Egger <daniel@eggers-club.de>

Author: bors[bot]

examples/serial.rs

@@ -0,0 +1,50 @@
+#![no_main]
+#![no_std]
+
+use panic_halt as _;
+
+use cortex_m;
+use cortex_m_rt::entry;
+use stm32f4xx_hal as hal;
+
+use crate::hal::{prelude::*, serial::config::Config, serial::Serial, stm32};
+
+use core::fmt::Write; // for pretty formatting of the serial output
+
+#[entry]
+fn main() -> ! {
+    let dp = stm32::Peripherals::take().unwrap();
+    let cp = cortex_m::peripheral::Peripherals::take().unwrap();
+
+    let gpioa = dp.GPIOA.split();
+
+    let rcc = dp.RCC.constrain();
+
+    let clocks = rcc.cfgr.use_hse(8.mhz()).freeze();
+
+    let mut delay = hal::delay::Delay::new(cp.SYST, clocks);
+
+    // define RX/TX pins
+    let tx_pin = gpioa.pa2.into_alternate_af7();
+    let rx_pin = gpioa.pa3.into_alternate_af7();
+
+    // configure serial
+    let serial = Serial::usart2(
+        dp.USART2,
+        (tx_pin, rx_pin),
+        Config::default().baudrate(9600.bps()),
+        clocks,
+    )
+    .unwrap();
+
+    let (mut tx, mut _rx) = serial.split();
+
+    let mut value: u8 = 0;
+
+    loop {
+        // print some value every 500 ms, value will overflow after 255
+        writeln!(tx, "value: {:02}\r", value).unwrap();
+        value += 1;
+        delay.delay_ms(500_u32);
+    }
+}