Merge pull request #341 from lulf/usart-dma-read

Add uart::Read DMA-based implementation

examples/stm32h7/src/bin/usart.rs

@@ -31,7 +31,7 @@ async fn main_task() {
 
     let mut buf = [0u8; 1];
     loop {
-        usart.read(&mut buf).unwrap();
+        usart.read_blocking(&mut buf).unwrap();
         usart.bwrite_all(&buf).unwrap();
     }
 }