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

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This commit is contained in:
Dean Camera 2011-02-26 15:57:06 +00:00
parent 6f01b6afd5
commit 66c38cd940
5 changed files with 32 additions and 13 deletions
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32
LUFA/Drivers/Peripheral/AVR8/TWI_AVR8.h
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@ -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);
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