/*
LUFA Library
- Copyright (C) Dean Camera, 2011.
+ Copyright (C) Dean Camera, 2012.
dean [at] fourwalledcubicle [dot] com
www.lufa-lib.org
*/
/*
- Copyright 2011 Dean Camera (dean [at] fourwalledcubicle [dot] com)
+ Copyright 2012 Dean Camera (dean [at] fourwalledcubicle [dot] com)
Permission to use, copy, modify, distribute, and sell this
software and its documentation for any purpose is hereby granted
*
* <b>Low Level API Example:</b>
* \code
- * // Initialize the TWI driver before first use
- * TWI_Init(TWI_BIT_PRESCALE_1, 10);
- *
+ * // Initialize the TWI driver before first use at 200KHz
+ * TWI_Init(TWI_BIT_PRESCALE_1, TWI_BITLENGTH_FROM_FREQ(1, 200000));
+ *
* // 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) == TWI_ERROR_NoError)
* {
* TWI_SendByte(0xDC);
- *
+ *
* TWI_SendByte(0x01);
* TWI_SendByte(0x02);
* TWI_SendByte(0x03);
- *
+ *
* // Must stop transmission afterwards to release the bus
* TWI_StopTransmission();
* }
- *
+ *
* // Start a read session to device at address 0xA0, internal address 0xDC with a 10ms timeout
* if (TWI_StartTransmission(0xA0 | TWI_ADDRESS_WRITE, 10) == TWI_ERROR_NoError)
* {
* TWI_SendByte(0xDC);
* TWI_StopTransmission();
- *
+ *
* if (TWI_StartTransmission(0xA0 | TWI_ADDRESS_READ, 10) == TWI_ERROR_NoError)
* {
* uint8_t Byte1, Byte2, Byte3;
- *
+ *
* // Read three bytes, acknowledge after the third byte is received
* TWI_ReceiveByte(&Byte1, false);
* TWI_ReceiveByte(&Byte2, false);
* TWI_ReceiveByte(&Byte3, true);
- *
+ *
* // Must stop transmission afterwards to release the bus
* TWI_StopTransmission();
* }
* }
* \endcode
- *
+ *
* <b>High Level API Example:</b>
* \code
- * // Initialize the TWI driver before first use
- * TWI_Init(TWI_BIT_PRESCALE_1, 10);
- *
+ * // Initialize the TWI driver before first use at 200KHz
+ * TWI_Init(TWI_BIT_PRESCALE_1, TWI_BITLENGTH_FROM_FREQ(1, 200000));
+ *
* // Start a write session to device at device address 0xA0, internal address 0xDC with a 10ms timeout
* uint8_t InternalWriteAddress = 0xDC;
* 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
*
* @{
/** TWI slave device address mask for a read session. Mask with a slave device base address to obtain
* the correct TWI bus address for the slave device when reading data from it.
*/
- #define TWI_ADDRESS_READ 0x00
+ #define TWI_ADDRESS_READ 0x01
/** TWI slave device address mask for a write session. Mask with a slave device base address to obtain
* the correct TWI bus address for the slave device when writing data to it.
*/
- #define TWI_ADDRESS_WRITE 0x01
+ #define TWI_ADDRESS_WRITE 0x00
/** Mask to retrieve the base address for a TWI device, which can then be ORed with \ref TWI_ADDRESS_READ
* or \ref TWI_ADDRESS_WRITE to obtain the device's read and write address respectively.
*/
#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 64. */
#define TWI_BIT_PRESCALE_64 ((1 << TWPS1) | (1 << TWPS0))
-
+
+ /** Calculates the length of each bit on the TWI bus for a given target frequency. This may be used with
+ * the \ref TWI_Init() function to convert a bus frequency to a number of clocks for the \c BitLength
+ * parameter.
+ *
+ * \param[in] Prescale Prescaler set on the TWI bus.
+ * \param[in] Frequency Desired TWI bus frequency in Hz.
+ *
+ * \return Bit length in clocks for the given TWI bus frequency at the given prescaler value.
+ */
+ #define TWI_BITLENGTH_FROM_FREQ(Prescale, Frequency) ((((F_CPU / (Prescale)) / (Frequency)) - 16) / 2)
+
/* Enums: */
/** Enum for the possible return codes of the TWI transfer start routine and other dependant TWI functions. */
enum TWI_ErrorCodes_t
TWI_ERROR_SlaveNotReady = 4, /**< Slave NAKed the TWI bus START condition. */
TWI_ERROR_SlaveNAK = 5, /**< Slave NAKed whilst attempting to send data to the device. */
};
-
+
/* Inline Functions: */
/** Initializes 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.
+ * \attention 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.
TWCR = ((1 << TWINT) | (1 << TWSTO) | (1 << TWEN));
}
+ /* Function Prototypes: */
+ /** Begins a master mode TWI bus communication with the given slave device address.
+ *
+ * \param[in] SlaveAddress Address of the slave TWI device to communicate with.
+ * \param[in] TimeoutMS Timeout period within which the slave must respond, in milliseconds.
+ *
+ * \return A value from the \ref TWI_ErrorCodes_t enum.
+ */
+ 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
*/
- 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);
- }
+ bool TWI_SendByte(const uint8_t Byte);
/** Receives a byte from the currently addressed device on the TWI bus.
*
*
* \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.
- *
- * \param[in] SlaveAddress Address of the slave TWI device to communicate with.
- * \param[in] TimeoutMS Timeout period within which the slave must respond, in milliseconds.
- *
- * \return A value from the \ref TWI_ErrorCodes_t enum.
- */
- uint8_t TWI_StartTransmission(const uint8_t SlaveAddress,
- const uint8_t TimeoutMS);
+ bool TWI_ReceiveByte(uint8_t* const Byte,
+ const bool LastByte) ATTR_NON_NULL_PTR_ARG(1);
/** High level function to perform a complete packet transfer over the TWI bus to the specified
* device.
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);
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