Add L4+ example for USART.

examples/stm32l4/src/bin/usart.rs

@@ -0,0 +1,89 @@
+
+#![no_std]
+#![no_main]
+#![feature(trait_alias)]
+#![feature(min_type_alias_impl_trait)]
+#![feature(impl_trait_in_bindings)]
+#![feature(type_alias_impl_trait)]
+#![allow(incomplete_features)]
+
+#[path = "../example_common.rs"]
+mod example_common;
+use cortex_m::prelude::_embedded_hal_blocking_serial_Write;
+use embassy::executor::Executor;
+use embassy::time::Clock;
+use embassy::util::Forever;
+use embassy_stm32::usart::{Config, Uart};
+use example_common::*;
+
+use cortex_m_rt::entry;
+use stm32l4::stm32l4x5 as pac;
+
+#[embassy::task]
+async fn main_task() {
+    let p = embassy_stm32::init(Default::default());
+
+    let config = Config::default();
+    let mut usart = Uart::new(p.UART4, p.PA1, p.PA0, config);
+
+    usart.bwrite_all(b"Hello Embassy World!\r\n").unwrap();
+    info!("wrote Hello, starting echo");
+
+    let mut buf = [0u8; 1];
+    loop {
+        usart.read(&mut buf).unwrap();
+        usart.bwrite_all(&buf).unwrap();
+    }
+}
+
+struct ZeroClock;
+
+impl Clock for ZeroClock {
+    fn now(&self) -> u64 {
+        0
+    }
+}
+
+static EXECUTOR: Forever<Executor> = Forever::new();
+
+#[entry]
+fn main() -> ! {
+    info!("Hello World!");
+
+    let pp = pac::Peripherals::take().unwrap();
+
+    pp.DBGMCU.cr.modify(|_, w| {
+        w.dbg_sleep().set_bit();
+        w.dbg_standby().set_bit();
+        w.dbg_stop().set_bit()
+    });
+
+    pp.RCC.ahb1enr.modify(|_, w| w.dma1en().set_bit());
+
+    pp.RCC.ahb2enr.modify(|_, w| {
+        w.gpioaen().set_bit();
+        w.gpioben().set_bit();
+        w.gpiocen().set_bit();
+        w.gpioden().set_bit();
+        w.gpioeen().set_bit();
+        w.gpiofen().set_bit();
+        w
+    });
+
+    pp.RCC.apb2enr.modify(|_, w| {
+        w.syscfgen().set_bit();
+        w
+    });
+    //pp.RCC.apb1enr.modify(|_, w| {
+    //w.usart3en().enabled();
+    //w
+    //});
+
+    unsafe { embassy::time::set_clock(&ZeroClock) };
+
+    let executor = EXECUTOR.put(Executor::new());
+
+    executor.run(|spawner| {
+        unwrap!(spawner.spawn(main_task()));
+    })
+}