Wait for idle or bus owner state in startTransmissionWIRE instead of storing repeated start state.

Author: sandeepmistry

cores/arduino/SERCOM.cpp

@@ -476,17 +476,12 @@ void SERCOM::prepareCommandBitsWire(SercomMasterCommandWire cmd)
 }
 
 bool SERCOM::startTransmissionWIRE(uint8_t address, SercomWireReadWriteFlag flag)
-{
-	return startTransmissionWIRE(address, flag, false);
-}
-
-bool SERCOM::startTransmissionWIRE(uint8_t address, SercomWireReadWriteFlag flag, bool repeatedStart)
 {
   // 7-bits address + 1-bits R/W
   address = (address << 0x1ul) | flag;
 
-  // Wait idle bus mode
-  while ( !repeatedStart && !isBusIdleWIRE());
+  // Wait idle or owner bus mode
+  while ( !isBusIdleWIRE() && !isBusOwnerWIRE() );
 
   // Send start and address
   sercom->I2CM.ADDR.bit.ADDR = address;
@@ -580,6 +575,11 @@ bool SERCOM::isBusIdleWIRE( void )
   return sercom->I2CM.STATUS.bit.BUSSTATE == WIRE_IDLE_STATE;
 }
 
+bool SERCOM::isBusOwnerWIRE( void )
+{
+  return sercom->I2CM.STATUS.bit.BUSSTATE == WIRE_OWNER_STATE;
+}
+
 bool SERCOM::isDataReadyWIRE( void )
 {
   return sercom->I2CS.INTFLAG.bit.DRDY;

cores/arduino/SERCOM.h

@@ -194,12 +194,12 @@ class SERCOM
     void prepareAckBitWIRE( void ) ;
     void prepareCommandBitsWire(SercomMasterCommandWire cmd);
 		bool startTransmissionWIRE(uint8_t address, SercomWireReadWriteFlag flag) ;
-		bool startTransmissionWIRE(uint8_t address, SercomWireReadWriteFlag flag, bool repeatedStart) ;
 		bool sendDataMasterWIRE(uint8_t data) ;
 		bool sendDataSlaveWIRE(uint8_t data) ;
 		bool isMasterWIRE( void ) ;
 		bool isSlaveWIRE( void ) ;
 		bool isBusIdleWIRE( void ) ;
+		bool isBusOwnerWIRE( void ) ;
 		bool isDataReadyWIRE( void ) ;
 		bool isStopDetectedWIRE( void ) ;
 		bool isRestartDetectedWIRE( void ) ;

libraries/Wire/Wire.cpp

@@ -68,7 +68,7 @@ uint8_t TwoWire::requestFrom(uint8_t address, size_t quantity, bool stopBit)
 
   size_t byteRead = 0;
 
-  if(sercom->startTransmissionWIRE(address, WIRE_READ_FLAG, repeatedStart))
+  if(sercom->startTransmissionWIRE(address, WIRE_READ_FLAG))
   {
     // Read first data
     rxBuffer.store_char(sercom->readDataWIRE());
@@ -83,7 +83,6 @@ uint8_t TwoWire::requestFrom(uint8_t address, size_t quantity, bool stopBit)
     sercom->prepareNackBitWIRE();                           // Prepare NACK to stop slave transmission
     //sercom->readDataWIRE();                               // Clear data register to send NACK
 
-    repeatedStart = !stopBit;
     if (stopBit)
     {
       sercom->prepareCommandBitsWire(WIRE_MASTER_ACT_STOP);   // Send Stop
@@ -117,7 +116,7 @@ uint8_t TwoWire::endTransmission(bool stopBit)
   transmissionBegun = false ;
 
   // Start I2C transmission
-  if ( !sercom->startTransmissionWIRE( txAddress, WIRE_WRITE_FLAG, repeatedStart ) )
+  if ( !sercom->startTransmissionWIRE( txAddress, WIRE_WRITE_FLAG ) )
   {
     sercom->prepareCommandBitsWire(WIRE_MASTER_ACT_STOP);
     return 2 ;  // Address error
@@ -134,7 +133,6 @@ uint8_t TwoWire::endTransmission(bool stopBit)
     }
   }
 
-  repeatedStart = !stopBit;
   if (stopBit)
   {
     sercom->prepareCommandBitsWire(WIRE_MASTER_ACT_STOP);

libraries/Wire/Wire.h

@@ -67,7 +67,6 @@ class TwoWire : public Stream
     uint8_t _uc_pinSCL;
 
     bool transmissionBegun;
-    bool repeatedStart;
 
     // RX Buffer
     RingBuffer rxBuffer;