Add iterator version of transactional interface

Author: eldruin

src/blocking/i2c.rs

@@ -271,6 +271,31 @@ pub trait Transactional {
     ) -> Result<(), Self::Error>;
 }
 
+/// Transactional I2C interface (iterator version).
+///
+/// This allows combining operation within an I2C transaction.
+pub trait TransactionalIter {
+    /// Error type
+    type Error;
+
+    /// Execute the provided operations on the I2C bus (iterator version).
+    ///
+    /// Transaction contract:
+    /// - Before executing the first operation an ST is sent automatically. This is followed by SAD+R/W as appropriate.
+    /// - Data from adjacent operations of the same type are sent after each other without an SP or SR.
+    /// - Between adjacent operations of a different type an SR and SAD+R/W is sent.
+    /// - After executing the last operation an SP is sent automatically.
+    /// - If the last operation is a `Read` the master does not send an acknowledge for the last byte.
+    ///
+    /// - `ST` = start condition
+    /// - `SAD+R/W` = slave address followed by bit 1 to indicate reading or 0 to indicate writing
+    /// - `SR` = repeated start condition
+    /// - `SP` = stop condition
+    fn try_exec_iter<'a, O>(&mut self, address: u8, operations: O) -> Result<(), Self::Error>
+    where
+        O: IntoIterator<Item = Operation<'a>>;
+}
+
 /// Default implementation of `blocking::i2c::Write`, `blocking::i2c::Read` and
 /// `blocking::i2c::WriteRead` traits for `blocking::i2c::Transactional` implementers.
 pub mod transactional {