Merge pull request #737 from ZhiyaoMa98/master

Prevent starting a new I2C transmission before previous stop finishes.

Author: burrbull

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Fixed
 
  - Fix transmission termination in I2C master DMA read [#736]
+ - Prevent starting a new I2C transmission before previous stop finishes [#737]
 
 ## [v0.20.0] - 2024-01-14
 

src/i2c.rs

@@ -285,6 +285,9 @@ impl<I2C: Instance> I2c<I2C> {
     /// Sends START and Address for writing
     #[inline(always)]
     fn prepare_write(&self, addr: u8) -> Result<(), Error> {
+        // Wait until a previous STOP condition finishes
+        while self.i2c.cr1.read().stop().bit_is_set() {}
+
         // Send a START condition
         self.i2c.cr1.modify(|_, w| w.start().set_bit());
 
@@ -327,6 +330,9 @@ impl<I2C: Instance> I2c<I2C> {
 
     /// Sends START and Address for reading
     fn prepare_read(&self, addr: u8) -> Result<(), Error> {
+        // Wait until a previous STOP condition finishes
+        while self.i2c.cr1.read().stop().bit_is_set() {}
+
         // Send a START condition and set ACK bit
         self.i2c
             .cr1
@@ -443,9 +449,6 @@ impl<I2C: Instance> I2c<I2C> {
             // Receive last byte
             *last = self.recv_byte()?;
 
-            // Wait for the STOP to be sent.
-            while self.i2c.cr1.read().stop().bit_is_set() {}
-
             // Fallthrough is success
             Ok(())
         } else {
@@ -465,9 +468,6 @@ impl<I2C: Instance> I2c<I2C> {
         // Send a STOP condition
         self.i2c.cr1.modify(|_, w| w.stop().set_bit());
 
-        // Wait for STOP condition to transmit.
-        while self.i2c.cr1.read().stop().bit_is_set() {}
-
         // Fallthrough is success
         Ok(())
     }
@@ -482,9 +482,6 @@ impl<I2C: Instance> I2c<I2C> {
         // Send a STOP condition
         self.i2c.cr1.modify(|_, w| w.stop().set_bit());
 
-        // Wait for STOP condition to transmit.
-        while self.i2c.cr1.read().stop().bit_is_set() {}
-
         // Fallthrough is success
         Ok(())
     }

src/i2c/dma.rs

@@ -628,7 +628,6 @@ where
                 // Wait for BTF
                 while self.hal_i2c.i2c.sr1.read().btf().bit_is_clear() {}
 
-                // Generate stop and wait for it
                 self.send_stop();
             }
         }
@@ -668,7 +667,7 @@ where
 
                 // Clear ACK
                 self.hal_i2c.i2c.cr1.modify(|_, w| w.ack().clear_bit());
-                // Generate stop and wait for it
+
                 self.send_stop();
             }
         }
@@ -730,7 +729,6 @@ where
 
                     self.rx.rx_transfer.as_mut().unwrap().start(|_| {});
                 } else {
-                    // Generate stop and wait for it
                     self.send_stop();
                 }
             }
@@ -756,7 +754,7 @@ where
 
                 // Clear ACK
                 self.hal_i2c.i2c.cr1.modify(|_, w| w.ack().clear_bit());
-                // Generate stop and wait for it
+
                 self.send_stop();
             }
         }