Added TWI baud rate prescaler and bit length parameters to the TWI_Init() function (thanks to Thomas Herlinghaus).

LUFA/Drivers/Peripheral/AVR8/TWI_AVR8.h

@@ -53,7 +53,7 @@
  *  <b>Low Level API Example:</b>
  *  \code
  *      // Initialise the TWI driver before first use
- *      TWI_Init();
+ *      TWI_Init(TWI_BIT_PRESCALE_1, 10);
  *
  *      // Start a write session to device at device address 0xA0, internal address 0xDC with a 10ms timeout
  *      if (TWI_StartTransmission(0xA0 | TWI_ADDRESS_WRITE, 10))
@@ -92,7 +92,7 @@
  *  <b>High Level API Example:</b>
  *  \code
  *      // Initialise the TWI driver before first use
- *      TWI_Init();
+ *      TWI_Init(TWI_BIT_PRESCALE_1, 10);
  *
  *      // Start a write session to device at device address 0xA0, internal address 0xDC with a 10ms timeout
  *      uint8_t InternalWriteAddress = 0xDC;
@@ -155,6 +155,18 @@
 			 */
 			#define TWI_DEVICE_ADDRESS_MASK  0xFE
 			
+			/** Bit length prescaler for \ref TWI_Init(). This mask multiplies the TWI bit length prescaler by 1. */
+			#define TWI_BIT_PRESCALE_1       ((0 << TWPS1) | (0 << TWPS0))
+			
+			/** Bit length prescaler for \ref TWI_Init(). This mask multiplies the TWI bit length prescaler by 4. */
+			#define TWI_BIT_PRESCALE_4       ((0 << TWPS1) | (1 << TWPS0))
+
+			/** Bit length prescaler for \ref TWI_Init(). This mask multiplies the TWI bit length prescaler by 16. */
+			#define TWI_BIT_PRESCALE_16      ((1 << TWPS1) | (0 << TWPS0))
+
+			/** Bit length prescaler for \ref TWI_Init(). This mask multiplies the TWI bit length prescaler by 64. */
+			#define TWI_BIT_PRESCALE_64      ((1 << TWPS1) | (1 << TWPS0))
+			
 		/* Enums: */
 			/** Enum for the possible return codes of the TWI transfer start routine and other dependant TWI functions. */
 			enum TWI_ErrorCodes_t
@@ -170,11 +182,21 @@
 		/* Inline Functions: */
 			/** Initialises the TWI hardware into master mode, ready for data transmission and reception. This must be
 			 *  before any other TWI operations.
+			 *
+			 *  The generated SCL frequency will be according to the formula <pre>F_CPU / (16 + 2 * BitLength + 4 ^ Prescale)</pre>.
+			 *
+			 *  \note The value of the \c BitLength parameter should not be set below 10 or invalid bus conditions may
+			 *        occur, as indicated in the AVR8 microcontroller datasheet.
+			 *
+			 *  \param[in] Prescale   Prescaler to use when determining the bus frequency, a \c TWI_BIT_PRESCALE_* value.
+			 *  \param[in] BitLength  Length of the bits sent on the bus.
 			 */
-			static inline void TWI_Init(void) ATTR_ALWAYS_INLINE;
-			static inline void TWI_Init(void)
+			static inline void TWI_Init(const uint8_t Prescale, const uint8_t BitLength) ATTR_ALWAYS_INLINE;
+			static inline void TWI_Init(const uint8_t Prescale, const uint8_t BitLength)
 			{
 				TWCR |= (1 << TWEN);
+				TWSR  = Prescale;
+				TWBR  = BitLength;
 			}
 
 			/** Turns off the TWI driver hardware. If this is called, any further TWI operations will require a call to

LUFA/ManPages/ChangeLog.txt

@@ -22,7 +22,8 @@
   *   - Added new MAX() and MIN() convenience macros
   *   - Added new Serial_SendData() function to the Serial driver
   *   - Added board driver support for the Sparkfun ATMEGA8U2 breakout board
-  *   - Started internal restructuring for eventual multiple architecture ports
+  *   - Added TWI baud rate prescaler and bit length parameters to the TWI_Init() function (thanks to Thomas Herlinghaus)
+  *   - Internal restructuring for eventual multiple architecture ports
   *   - Added start of an AVR32 UC3B architecture port (currently incomplete/experimental)
   *  - Library Applications:
   *   - Added ability to write protect Mass Storage disk write operations from the host OS

Projects/MIDIToneGenerator/makefile

@@ -116,7 +116,7 @@ OBJDIR = .
 
 
 # Path to the LUFA library
-LUFA_PATH = ../../
+LUFA_PATH = ../..
 
 
 # LUFA library compile-time options and predefined tokens

Projects/TempDataLogger/TempDataLogger.c

@@ -151,10 +151,6 @@ int main(void)
 	LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 	sei();
 
-	/* Discard the first sample from the temperature sensor, as it is generally incorrect */
-	volatile uint8_t Dummy = Temperature_GetTemperature();
-	(void)Dummy;
-
 	for (;;)
 	{
 		MS_Device_USBTask(&Disk_MS_Interface);
@@ -204,7 +200,7 @@ void SetupHardware(void)
 	Temperature_Init();
 	Dataflash_Init();
 	USB_Init();
-	TWI_Init();
+	TWI_Init(TWI_BIT_PRESCALE_4, (F_CPU / 4 / 50000) / 2);
 
 	/* 500ms logging interval timer configuration */
 	OCR1A   = (((F_CPU / 1024) / 2) - 1);