diff --git a/src/prelude.rs b/src/prelude.rs
index 4d17043ad..55f0b5d8d 100644
--- a/src/prelude.rs
+++ b/src/prelude.rs
@@ -28,6 +28,8 @@ pub use digital::ToggleableOutputPin as _embedded_hal_digital_ToggleableOutputPi
 pub use serial::Read as _embedded_hal_serial_Read;
 pub use serial::Write as _embedded_hal_serial_Write;
 pub use spi::FullDuplex as _embedded_hal_spi_FullDuplex;
+#[cfg(feature = "unproven")]
+pub use spi::Send as _embedded_hal_spi_Send;
 pub use timer::CountDown as _embedded_hal_timer_CountDown;
 #[cfg(feature = "unproven")]
 pub use watchdog::Watchdog as _embedded_hal_watchdog_Watchdog;
diff --git a/src/spi.rs b/src/spi.rs
index b91e6d68b..92387a237 100644
--- a/src/spi.rs
+++ b/src/spi.rs
@@ -26,6 +26,38 @@ pub trait FullDuplex<Word> {
     fn send(&mut self, word: Word) -> nb::Result<(), Self::Error>;
 }
 
+/// Write (master mode)
+///
+/// # Notes
+///
+/// - It's the task of the user of this interface to manage the slave select lines
+///
+/// - The slave select line shouldn't be released before the `flush` call succeeds
+#[cfg(feature = "unproven")]
+pub trait Send<Word> {
+    /// An enumeration of SPI errors
+    type Error;
+
+    /// Sends a word to the slave
+    fn send(&mut self, word: Word) -> nb::Result<(), Self::Error>;
+
+    /// Ensures that none of the previously written words are still buffered
+    fn completed(&mut self) -> nb::Result<(), Self::Error>;
+}
+
+/// Write (master mode)
+#[cfg(feature = "unproven")]
+impl<W, E> Send<W> for FullDuplex<W, Error = E> {
+    type Error = E;
+    fn send(&mut self, word: W) -> nb::Result<(), Self::Error> {
+        self.send(word)
+    }
+
+    fn completed(&mut self) -> nb::Result<(), Self::Error> {
+        self.read().map(|_| ())
+    }
+}
+
 /// Clock polarity
 #[derive(Clone, Copy, PartialEq, Eq)]
 pub enum Polarity {
@@ -75,4 +107,4 @@ pub const MODE_2: Mode = Mode {
 pub const MODE_3: Mode = Mode {
     polarity: Polarity::IdleHigh,
     phase: Phase::CaptureOnSecondTransition,
-};
\ No newline at end of file
+};