Revert changes to twim, belongs in another branch

Author: Henrik Alsér

nrf-hal-common/src/twim.rs

@@ -124,21 +124,16 @@ where
             // values.
             unsafe { w.maxcnt().bits(buffer.len() as _) });
 
-        // Clear address NACK
-        self.0.errorsrc.write(|w| w.anack().bit(true));
-
         // Start write operation
         self.0.tasks_starttx.write(|w|
             // `1` is a valid value to write to task registers.
             unsafe { w.bits(1) });
 
         // Wait until write operation is about to end
-        while self.0.events_lasttx.read().bits() == 0
-            && self.0.errorsrc.read().anack().is_not_received()
-        {}
+        while self.0.events_lasttx.read().bits() == 0 {}
         self.0.events_lasttx.write(|w| w); // reset event
 
-        // Stop write operation
+        // Stop read operation
         self.0.tasks_stop.write(|w|
             // `1` is a valid value to write to task registers.
             unsafe { w.bits(1) });
@@ -152,10 +147,6 @@ where
         // after all possible DMA actions have completed
         compiler_fence(SeqCst);
 
-        if self.0.errorsrc.read().anack().is_received() {
-            return Err(Error::AddressNack);
-        }
-
         if self.0.txd.amount.read().bits() != buffer.len() as u32 {
             return Err(Error::Transmit);
         }
@@ -205,18 +196,13 @@ where
             // full range of values that fit in a `u8`.
             unsafe { w.maxcnt().bits(buffer.len() as _) });
 
-        // Clear address NACK
-        self.0.errorsrc.write(|w| w.anack().bit(true));
-
         // Start read operation
         self.0.tasks_startrx.write(|w|
             // `1` is a valid value to write to task registers.
             unsafe { w.bits(1) });
 
         // Wait until read operation is about to end
-        while self.0.events_lastrx.read().bits() == 0
-            && self.0.errorsrc.read().anack().is_not_received()
-        {}
+        while self.0.events_lastrx.read().bits() == 0 {}
         self.0.events_lastrx.write(|w| w); // reset event
 
         // Stop read operation
@@ -233,10 +219,6 @@ where
         // after all possible DMA actions have completed
         compiler_fence(SeqCst);
 
-        if self.0.errorsrc.read().anack().is_received() {
-            return Err(Error::AddressNack);
-        }
-
         if self.0.rxd.amount.read().bits() != buffer.len() as u32 {
             return Err(Error::Receive);
         }
@@ -315,47 +297,23 @@ where
             // full range of values that fit in a `u8`.
             unsafe { w.maxcnt().bits(rd_buffer.len() as _) });
 
-        // Clear address NACK
-        self.0.errorsrc.write(|w| w.anack().bit(true));
+        // Immediately start RX after TX, then stop
+        self.0
+            .shorts
+            .modify(|_r, w| w.lasttx_startrx().enabled().lastrx_stop().enabled());
 
         // Start write operation
-        // `1` is a valid value to write to task registers.
-        self.0.tasks_starttx.write(|w| unsafe { w.bits(1) });
-
-        // Wait until write operation is about to end
-        while self.0.events_lasttx.read().bits() == 0
-            && self.0.errorsrc.read().anack().is_not_received()
-        {}
-        self.0.events_lasttx.write(|w| w); // reset event
-
-        // Stop operation if address is NACK
-        if self.0.errorsrc.read().anack().is_received() {
+        self.0.tasks_starttx.write(|w|
             // `1` is a valid value to write to task registers.
-            self.0.tasks_stop.write(|w| unsafe { w.bits(1) });
-            // Wait until operation is stopped
-            while self.0.events_stopped.read().bits() == 0 {}
-            self.0.events_stopped.write(|w| w); // reset event
-            return Err(Error::AddressNack);
-        }
-
-        // Start read operation
-        // `1` is a valid value to write to task registers.
-        self.0.tasks_startrx.write(|w| unsafe { w.bits(1) });
-
-        // Wait until read operation is about to end
-        while self.0.events_lastrx.read().bits() == 0 {}
-        self.0.events_lastrx.write(|w| w); // reset event
-
-        // Stop read operation
-        // `1` is a valid value to write to task registers.
-        self.0.tasks_stop.write(|w| unsafe { w.bits(1) });
+            unsafe { w.bits(1) });
 
         // Wait until total operation has ended
         while self.0.events_stopped.read().bits() == 0 {}
 
         self.0.events_lasttx.write(|w| w); // reset event
         self.0.events_lastrx.write(|w| w); // reset event
         self.0.events_stopped.write(|w| w); // reset event
+        self.0.shorts.write(|w| w);
 
         // Conservative compiler fence to prevent optimizations that do not
         // take in to account actions by DMA. The fence has been placed here,
@@ -569,7 +527,6 @@ pub enum Error {
     Transmit,
     Receive,
     DMABufferNotInDataMemory,
-    AddressNack,
 }
 
 /// Implemented by all TWIM instances