Make TWI_ReadPacket() use a repeated start condition rather than a full bus release/recapture after the read address has been sent.

Fix TWI_ReadPacket() not releasing the bus correctly after all data transferred.

Make TWI_SendByte() and TWI_ReceiveByte() non-inline to reduce compiled binary size.

LUFA/Drivers/Peripheral/AVR8/TWI_AVR8.c

@@ -97,34 +97,69 @@ uint8_t TWI_StartTransmission(const uint8_t SlaveAddress,
 	}
 }
 
+bool TWI_SendByte(const uint8_t Byte)
+{
+	TWDR = Byte;
+	TWCR = ((1 << TWINT) | (1 << TWEN));
+	while (!(TWCR & (1 << TWINT)));
+
+	return ((TWSR & TW_STATUS_MASK) == TW_MT_DATA_ACK);
+}
+
+bool TWI_ReceiveByte(uint8_t* const Byte,
+					 const bool LastByte)
+{
+	uint8_t TWCRMask;
+
+	if (LastByte)
+	  TWCRMask = ((1 << TWINT) | (1 << TWEN));
+	else
+	  TWCRMask = ((1 << TWINT) | (1 << TWEN) | (1 << TWEA));
+
+	TWCR = TWCRMask;
+	while (!(TWCR & (1 << TWINT)));
+	*Byte = TWDR;
+	
+	uint8_t Status = (TWSR & TW_STATUS_MASK);
+	
+	return ((LastByte) ? (Status == TW_MR_DATA_NACK) : (Status == TW_MR_DATA_ACK));
+}
+
 uint8_t TWI_ReadPacket(const uint8_t SlaveAddress,
                        const uint8_t TimeoutMS,
                        const uint8_t* InternalAddress,
-                       const uint8_t InternalAddressLen,
+                       uint8_t InternalAddressLen,
                        uint8_t* Buffer,
                        uint8_t Length)
 {
 	uint8_t ErrorCode;
 	
-	if ((ErrorCode = TWI_WritePacket(SlaveAddress, TimeoutMS, InternalAddress, InternalAddressLen,
+	if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_WRITE,
-	                                 NULL, 0)) != TWI_ERROR_NoError)
+	                                       TimeoutMS)) == TWI_ERROR_NoError)
 	{
-		return ErrorCode;
+		while (InternalAddressLen--)
-	}
-
-	if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_READ,
-										   TimeoutMS)) == TWI_ERROR_NoError)
-	{
-		while (Length--)
 		{
-			if (!(TWI_ReceiveByte(Buffer++, (Length == 1))))
+			if (!(TWI_SendByte(*(InternalAddress++))))
-			{
+			{				
 				ErrorCode = TWI_ERROR_SlaveNAK;
 				break;
 			}
 		}
 		
-		TWI_StopTransmission();
+		if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_READ,
+											   TimeoutMS)) == TWI_ERROR_NoError)
+		{
+			while (Length--)
+			{
+				if (!(TWI_ReceiveByte(Buffer++, (Length == 0))))
+				{
+					ErrorCode = TWI_ERROR_SlaveNAK;
+					break;
+				}
+			}
+			
+			TWI_StopTransmission();
+		}
 	}
 	
 	return ErrorCode;
@@ -145,7 +180,7 @@ uint8_t TWI_WritePacket(const uint8_t SlaveAddress,
 		while (InternalAddressLen--)
 		{
 			if (!(TWI_SendByte(*(InternalAddress++))))
-			{
+			{				
 				ErrorCode = TWI_ERROR_SlaveNAK;
 				break;
 			}

LUFA/Drivers/Peripheral/AVR8/TWI_AVR8.h

@@ -99,14 +99,14 @@
  *      uint8_t WritePacket[3] = {0x01, 0x02, 0x03};
  *
  *      TWI_WritePacket(0xA0, 10, &InternalWriteAddress, sizeof(InternalWriteAddress),
- *                      WritePacket, sizeof(WritePacket);
+ *                      &WritePacket, sizeof(WritePacket);
  *
  *      // Start a read session to device at address 0xA0, internal address 0xDC with a 10ms timeout
  *      uint8_t InternalReadAddress = 0xDC;
  *      uint8_t ReadPacket[3];
  *
  *      TWI_ReadPacket(0xA0, 10, &InternalReadAddress, sizeof(InternalReadAddress),
- *                     ReadPacket, sizeof(ReadPacket);
+ *                     &ReadPacket, sizeof(ReadPacket);
  *  \endcode
  *
  *  @{
@@ -215,43 +215,6 @@
 				TWCR = ((1 << TWINT) | (1 << TWSTO) | (1 << TWEN));
 			}
 
-			/** Sends a byte to the currently addressed device on the TWI bus.
-			 *
-			 *  \param[in] Byte  Byte to send to the currently addressed device
-			 *
-			 *  \return Boolean \c true if the recipient ACKed the byte, \c false otherwise
-			 */
-			static inline bool TWI_SendByte(const uint8_t Byte)
-			{
-				TWDR = Byte;
-				TWCR = ((1 << TWINT) | (1 << TWEN));
-				while (!(TWCR & (1 << TWINT)));
-
-				return ((TWSR & TW_STATUS_MASK) == TW_MT_DATA_ACK);
-			}
-
-			/** Receives a byte from the currently addressed device on the TWI bus.
-			 *
-			 *  \param[in] Byte      Location where the read byte is to be stored.
-			 *  \param[in] LastByte  Indicates if the byte should be ACKed if false, NAKed if true.
-			 *
-			 *  \return Boolean \c true if the byte reception successfully completed, \c false otherwise.
-			 */
-			static inline bool TWI_ReceiveByte(uint8_t* const Byte,
-			                                   const bool LastByte)
-			{
-				uint8_t TWCRMask = ((1 << TWINT) | (1 << TWEN));
-
-				if (!(LastByte))
-				  TWCRMask |= (1 << TWEA);
-
-				TWCR = TWCRMask;
-				while (!(TWCR & (1 << TWINT)));
-				*Byte = TWDR;
-
-				return ((TWSR & TW_STATUS_MASK) == TW_MR_DATA_ACK);
-			}
-
 		/* Function Prototypes: */
 			/** Begins a master mode TWI bus communication with the given slave device address.
 			 *
@@ -263,6 +226,26 @@
 			uint8_t TWI_StartTransmission(const uint8_t SlaveAddress,
 			                              const uint8_t TimeoutMS);
 
+			/** Sends a byte to the currently addressed device on the TWI bus.
+			 *
+			 *  \param[in] Byte  Byte to send to the currently addressed device
+			 *
+			 *  \return Boolean \c true if the recipient ACKed the byte, \c false otherwise
+			 */
+			bool TWI_SendByte(const uint8_t Byte);
+
+			/** Receives a byte from the currently addressed device on the TWI bus.
+			 *
+			 *  \param[in] Byte      Location where the read byte is to be stored.
+			 *  \param[in] LastByte  Indicates if the byte should be ACKed if false, NAKed if true.
+			 *
+			 *  \return Boolean \c true if the byte reception successfully completed, \c false otherwise.
+			 */
+			bool TWI_ReceiveByte(uint8_t* const Byte,
+			                     const bool LastByte) ATTR_NON_NULL_PTR_ARG(1);
+			bool TWI_ReceiveByte(uint8_t* const Byte,
+			                     const bool LastByte);
+					 
 			/** High level function to perform a complete packet transfer over the TWI bus to the specified
 			 *  device.
 			 *
@@ -278,7 +261,7 @@
 			uint8_t TWI_ReadPacket(const uint8_t SlaveAddress,
 			                       const uint8_t TimeoutMS,
 			                       const uint8_t* InternalAddress,
-			                       const uint8_t InternalAddressLen,
+			                       uint8_t InternalAddressLen,
 			                       uint8_t* Buffer,
 			                       uint8_t Length) ATTR_NON_NULL_PTR_ARG(3);