Implement fmt::Write for serial

CHANGELOG.md

@@ -65,6 +65,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
   source for the systemclock. Also `Clocks::pllclk()` was introduced to be able
   to check, whether PLL is used.
 - Add unsafe peripheral function to access underlying peripheral ([#277])
+- Implement `fmt::Write` for `Serial` ([#278])
+  - This allowes using `writeln!` in combination with `Serial`.
 
 [`enumset`]: https://crates.io/crates/enumset
 
@@ -470,6 +472,7 @@ let clocks = rcc
 [defmt]: https://github.com/knurling-rs/defmt
 [filter]: https://defmt.ferrous-systems.com/filtering.html
 
+[#278]: https://github.com/stm32-rs/stm32f3xx-hal/pull/278
 [#277]: https://github.com/stm32-rs/stm32f3xx-hal/pull/277
 [#273]: https://github.com/stm32-rs/stm32f3xx-hal/pull/273
 [#271]: https://github.com/stm32-rs/stm32f3xx-hal/pull/271

src/serial.rs

@@ -15,7 +15,7 @@ use core::{
 
 use crate::{
     gpio::{gpioa, gpiob, gpioc, AF7},
-    hal::{blocking, serial},
+    hal::{blocking, serial, serial::Write},
     pac::{
         self,
         rcc::cfgr3::USART1SW_A,
@@ -926,7 +926,7 @@ where
     }
 }
 
-impl<Usart, Tx, Rx> serial::Write<u8> for Serial<Usart, (Tx, Rx)>
+impl<Usart, Pins> serial::Write<u8> for Serial<Usart, Pins>
 where
     Usart: Instance,
 {
@@ -954,6 +954,17 @@ where
     }
 }
 
+impl<Usart, Pins> fmt::Write for Serial<Usart, Pins>
+where
+    Serial<Usart, Pins>: serial::Write<u8>,
+{
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        s.bytes()
+            .try_for_each(|c| nb::block!(self.write(c)))
+            .map_err(|_| fmt::Error)
+    }
+}
+
 impl<USART, TX, RX> blocking::serial::write::Default<u8> for Serial<USART, (TX, RX)> where
     USART: Instance
 {
@@ -994,6 +1005,17 @@ where
     }
 }
 
+impl<Usart, Pin> fmt::Write for Tx<Usart, Pin>
+where
+    Tx<Usart, Pin>: serial::Write<u8>,
+{
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        s.bytes()
+            .try_for_each(|c| nb::block!(self.write(c)))
+            .map_err(|_| fmt::Error)
+    }
+}
+
 impl<Usart, Pin> Rx<Usart, Pin>
 where
     Usart: Instance + Dma,