* <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))
* <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;
*/
#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
/* 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);
+ 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
* - 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
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);
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);
projects / pub / lufa.git / commitdiff