Implement review items

Author: jbeaurivage

Cargo.toml

@@ -20,4 +20,6 @@ embedded-hal = "1.0.0"
 
 [features]
 mosi_idle_high = []
+# Send the reset command in one single transaction
+reset_single_transaction = []
 std = []

README.md

@@ -39,7 +39,7 @@ It provides three variants:
   It may also be a timing issue with the first bit being sent, this is the case
   on the stm32f030 with 2MHz.
 
-  You could try using the `mosi_idle_high` feature, it might help.
+  You could try using the `mosi_idle_high` and `reset_single_transaction` features, they might help.
 
   If this does not help you can try different `embedded_hal::spi::Mode` parameters. For example on
   stm32f411 (as used for example on the Black Pill board) you have to set `phase` to

src/prerendered.rs

@@ -11,6 +11,8 @@ use core::marker::PhantomData;
 
 use smart_leds_trait::{SmartLedsWrite, RGB8, RGBW};
 
+const FLUSH_DATA_LEN: usize = 140;
+
 /// SPI mode that can be used for this crate
 ///
 /// Provided for convenience
@@ -114,18 +116,28 @@ where
     }
 
     /// Add a reset sequence (140 zeroes) to the data buffer
+    #[cfg(feature = "reset_single_transaction")]
     fn flush(&mut self) -> Result<(), Error<E>> {
-        const FLUSH_DATA_LEN: usize = 140;
-        const FLUSH_DATA: &[u8] = &[0x00; FLUSH_DATA_LEN];
+        let flush_data = [(); FLUSH_DATA_LEN].map(|_| 0);
 
         if self.index + FLUSH_DATA_LEN > self.data.len() {
             return Err(Error::OutOfBounds);
         }
-        self.data[self.index..(self.index + FLUSH_DATA_LEN)].copy_from_slice(FLUSH_DATA);
+        self.data[self.index..(self.index + FLUSH_DATA_LEN)].copy_from_slice(&flush_data);
         self.index += FLUSH_DATA_LEN;
         Ok(())
     }
 
+    /// Send a reset sequence (140 zeroes) on the bus
+    #[cfg(not(feature = "reset_single_transaction"))]
+    fn flush(&mut self) -> Result<(), Error<E>> {
+        for _ in 0..FLUSH_DATA_LEN {
+            self.spi.write(&[0]).map_err(Error::Spi)?;
+        }
+
+        Ok(())
+    }
+
     fn send_data(&mut self) -> Result<(), E> {
         self.spi.write(&self.data[..self.index])
     }
@@ -157,7 +169,7 @@ where
         }
 
         self.flush()?;
-        self.send_data().map_err(|e| Error::Spi(e))
+        self.send_data().map_err(Error::Spi)
     }
 }
 
@@ -188,6 +200,6 @@ where
         }
 
         self.flush()?;
-        self.send_data().map_err(|e| Error::Spi(e))
+        self.send_data().map_err(Error::Spi)
     }
 }