Added new high level TWI packet read/write commands, altered behaviour of the TWI_StartTransmission() function.
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Dean Camera
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13 changed files with 225 additions and 92 deletions
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@ -49,13 +49,16 @@
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* The following snippet is an example of how this module may be used within a typical
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* application.
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*
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* <b>Low Level API Example:</b>
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* \code
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* // Initialise the TWI driver before first use
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* TWI_Init();
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*
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* // Start a write session to device at address 0xA0 with a 10ms timeout
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* // Start a write session to device at device address 0xA0, internal address 0xDC with a 10ms timeout
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* if (TWI_StartTransmission(0xA0 | TWI_ADDRESS_WRITE, 10))
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* {
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* TWI_SendByte(0xDC);
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*
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* TWI_SendByte(0x01);
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* TWI_SendByte(0x02);
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* TWI_SendByte(0x03);
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@ -64,21 +67,47 @@
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* TWI_StopTransmission();
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* }
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*
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* // Start a read session to device at address 0xA0 with a 10ms timeout
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* if (TWI_StartTransmission(0xA0 | TWI_ADDRESS_READ, 10))
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* // Start a read session to device at address 0xA0, internal address 0xDC with a 10ms timeout
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* if (TWI_StartTransmission(0xA0 | TWI_ADDRESS_WRITE, 10))
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* {
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* uint8_t Byte1, Byte2, Byte3;
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*
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* // Read three bytes, acknowledge after the third byte is received
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* TWI_ReceiveByte(&Byte1, false);
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* TWI_ReceiveByte(&Byte2, false);
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* TWI_ReceiveByte(&Byte3, true);
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*
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* // Must stop transmission afterwards to release the bus
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* TWI_SendByte(0xDC);
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* TWI_StopTransmission();
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*
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* if (TWI_StartTransmission(0xA0 | TWI_ADDRESS_READ, 10))
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* {
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* uint8_t Byte1, Byte2, Byte3;
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*
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* // Read three bytes, acknowledge after the third byte is received
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* TWI_ReceiveByte(&Byte1, false);
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* TWI_ReceiveByte(&Byte2, false);
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* TWI_ReceiveByte(&Byte3, true);
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*
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* // Must stop transmission afterwards to release the bus
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* TWI_StopTransmission();
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* }
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* }
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* \endcode
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*
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* <b>High Level API Example:</b>
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* \code
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* // Initialise the TWI driver before first use
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* TWI_Init();
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*
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* // Start a write session to device at device address 0xA0, internal address 0xDC with a 10ms timeout
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* uint8_t InternalWriteAddress = 0xDC;
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* uint8_t WritePacket[3] = {0x01, 0x02, 0x03};
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*
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* TWI_WritePacket(0xA0, 10, &InternalWriteAddress, sizeof(InternalWriteAddress),
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* &WritePacket, sizeof(WritePacket);
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*
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* // Start a read session to device at address 0xA0, internal address 0xDC with a 10ms timeout
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* uint8_t InternalReadAddress = 0xDC;
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* uint8_t ReadPacket[3];
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*
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* TWI_ReadPacket(0xA0, 10, &InternalReadAddress, sizeof(InternalReadAddress),
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* &ReadPacket, sizeof(ReadPacket);
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* \endcode
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*
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* @{
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*/
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@ -90,6 +119,7 @@
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#include <avr/io.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <util/twi.h>
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#include <util/delay.h>
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@ -108,12 +138,29 @@
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/** TWI slave device address mask for a read session. Mask with a slave device base address to obtain
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* the correct TWI bus address for the slave device when reading data from it.
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*/
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#define TWI_ADDRESS_READ 0x00
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#define TWI_ADDRESS_READ 0x00
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/** TWI slave device address mask for a write session. Mask with a slave device base address to obtain
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* the correct TWI bus address for the slave device when writing data to it.
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*/
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#define TWI_ADDRESS_WRITE 0x01
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#define TWI_ADDRESS_WRITE 0x01
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/** Mask to retrieve the base address for a TWI device, which can then be ORed with \ref TWI_ADDRESS_READ
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* or \ref TWI_ADDRESS_WRITE to obtain the device's read and write address respectively.
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*/
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#define TWI_DEVICE_ADDRESS_MASK 0xFE
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/* Enums: */
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/** Enum for the possible return codes of the TWI transfer start routine and other dependant TWI functions. */
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enum TWI_ErrorCodes_t
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{
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TWI_ERROR_NoError = 0, /**< Indicates that the command completed sucessfully. */
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TWI_ERROR_BusFault = 1, /**< A TWI bus fault occurred while attempting to capture the bus. */
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TWI_ERROR_BusCaptureTimeout = 2, /**< A timeout occurred whilst waiting for the bus to be ready. */
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TWI_ERROR_SlaveResponseTimeout = 3, /**< No ACK received at the nominated slave address within the timeout period. */
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TWI_ERROR_SlaveNotReady = 4, /**< Slave NAKed the TWI bus START condition. */
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TWI_ERROR_SlaveNAK = 5, /**< Slave NAKed whilst attempting to send data to the device. */
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};
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/* Inline Functions: */
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/** Initialises the TWI hardware into master mode, ready for data transmission and reception. This must be
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@ -163,8 +210,8 @@
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*
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* \return Boolean \c true if the byte reception successfully completed, \c false otherwise
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*/
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static inline bool TWI_ReceiveByte(uint8_t* const Byte,
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const bool LastByte)
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static inline uint8_t TWI_ReceiveByte(uint8_t* const Byte,
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const bool LastByte)
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{
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uint8_t TWCRMask = ((1 << TWINT) | (1 << TWEN));
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@ -184,10 +231,44 @@
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* \param[in] SlaveAddress Address of the slave TWI device to communicate with
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* \param[in] TimeoutMS Timeout period within which the slave must respond, in milliseconds
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*
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* \return Boolean \c true if the device is ready for data, \c false otherwise
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* \return A value from the \ref TWI_ErrorCodes_t enum
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*/
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bool TWI_StartTransmission(const uint8_t SlaveAddress,
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const uint8_t TimeoutMS);
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uint8_t TWI_StartTransmission(const uint8_t SlaveAddress,
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const uint8_t TimeoutMS);
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/** High level function to perform a complete packet transfer over the TWI bus to the specified
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* device.
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*
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* \param[in] SlaveAddress Base address of the TWI slave device to communicate with
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* \param[in] TimeoutMS Timeout for bus capture and slave START ACK, in milliseconds
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* \param[in] InternalAddress Pointer to a location where the internal slave read start address is stored
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* \param[in] InternalAddressLen Size of the internal device address, in bytes
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* \param[in] Buffer Pointer to a buffer where the read packet data is to be stored
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* \param[in] Length Size of the packet to read, in bytes
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*/
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uint8_t TWI_ReadPacket(const uint8_t SlaveAddress,
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const uint8_t TimeoutMS,
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const uint8_t* InternalAddress,
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uint8_t InternalAddressLen,
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uint8_t* Buffer,
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uint8_t Length);
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/** High level function to perform a complete packet transfer over the TWI bus from the specified
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* device.
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*
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* \param[in] SlaveAddress Base address of the TWI slave device to communicate with
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* \param[in] TimeoutMS Timeout for bus capture and slave START ACK, in milliseconds
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* \param[in] InternalAddress Pointer to a location where the internal slave write start address is stored
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* \param[in] InternalAddressLen Size of the internal device address, in bytes
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* \param[in] Buffer Pointer to a buffer where the packet data to send is stored
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* \param[in] Length Size of the packet to send, in bytes
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*/
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uint8_t TWI_WritePacket(const uint8_t SlaveAddress,
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const uint8_t TimeoutMS,
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const uint8_t* InternalAddress,
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uint8_t InternalAddressLen,
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const uint8_t* Buffer,
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uint8_t Length);
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/* Disable C linkage for C++ Compilers: */
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#if defined(__cplusplus)
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