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Added new high level TWI packet read/write commands, altered behaviour of the TWI_StartTransmission() function.

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This commit is contained in:
Dean Camera 2011-01-13 22:56:49 +00:00
parent 9c7594e7db
commit 70d55f6e0c
13 changed files with 225 additions and 92 deletions
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117
LUFA/Drivers/Peripheral/AVRU4U6U7/TWI.h
View file

@ -49,13 +49,16 @@
* The following snippet is an example of how this module may be used within a typical
* application.
*
* <b>Low Level API Example:</b>
* \code
* // Initialise the TWI driver before first use
* TWI_Init();
*
* // Start a write session to device at address 0xA0 with a 10ms timeout
* // 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_SendByte(0xDC);
*
* TWI_SendByte(0x01);
* TWI_SendByte(0x02);
* TWI_SendByte(0x03);
@ -64,21 +67,47 @@
* TWI_StopTransmission();
* }
*
* // Start a read session to device at address 0xA0 with a 10ms timeout
* if (TWI_StartTransmission(0xA0 | TWI_ADDRESS_READ, 10))
* // Start a read session to device at address 0xA0, internal address 0xDC with a 10ms timeout
* if (TWI_StartTransmission(0xA0 | TWI_ADDRESS_WRITE, 10))
* {
* 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_SendByte(0xDC);
* TWI_StopTransmission();
*
* if (TWI_StartTransmission(0xA0 | TWI_ADDRESS_READ, 10))
* {
* 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
* // Initialise the TWI driver before first use
* TWI_Init();
*
* // 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);
*
* // 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);
* \endcode
*
* @{
*/
@ -90,6 +119,7 @@
#include <avr/io.h>
#include <stdbool.h>
#include <stdio.h>
#include <util/twi.h>
#include <util/delay.h>
@ -108,12 +138,29 @@
/** 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 0x00
/** 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 0x01
/** 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
/* Enums: */
/** Enum for the possible return codes of the TWI transfer start routine and other dependant TWI functions. */
enum TWI_ErrorCodes_t
{
TWI_ERROR_NoError = 0, /**< Indicates that the command completed sucessfully. */
TWI_ERROR_BusFault = 1, /**< A TWI bus fault occurred while attempting to capture the bus. */
TWI_ERROR_BusCaptureTimeout = 2, /**< A timeout occurred whilst waiting for the bus to be ready. */
TWI_ERROR_SlaveResponseTimeout = 3, /**< No ACK received at the nominated slave address within the timeout period. */
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: */
/** Initialises the TWI hardware into master mode, ready for data transmission and reception. This must be
@ -163,8 +210,8 @@
*
* \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)
static inline uint8_t TWI_ReceiveByte(uint8_t* const Byte,
const bool LastByte)
{
uint8_t TWCRMask = ((1 << TWINT) | (1 << TWEN));
@ -184,10 +231,44 @@
* \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 Boolean \c true if the device is ready for data, \c false otherwise
* \return A value from the \ref TWI_ErrorCodes_t enum
*/
bool TWI_StartTransmission(const uint8_t SlaveAddress,
const uint8_t TimeoutMS);
uint8_t TWI_StartTransmission(const uint8_t SlaveAddress,
const uint8_t TimeoutMS);
/** High level function to perform a complete packet transfer over the TWI bus to the specified
* device.
*
* \param[in] SlaveAddress Base address of the TWI slave device to communicate with
* \param[in] TimeoutMS Timeout for bus capture and slave START ACK, in milliseconds
* \param[in] InternalAddress Pointer to a location where the internal slave read start address is stored
* \param[in] InternalAddressLen Size of the internal device address, in bytes
* \param[in] Buffer Pointer to a buffer where the read packet data is to be stored
* \param[in] Length Size of the packet to read, in bytes
*/
uint8_t TWI_ReadPacket(const uint8_t SlaveAddress,
const uint8_t TimeoutMS,
const uint8_t* InternalAddress,
uint8_t InternalAddressLen,
uint8_t* Buffer,
uint8_t Length);
/** High level function to perform a complete packet transfer over the TWI bus from the specified
* device.
*
* \param[in] SlaveAddress Base address of the TWI slave device to communicate with
* \param[in] TimeoutMS Timeout for bus capture and slave START ACK, in milliseconds
* \param[in] InternalAddress Pointer to a location where the internal slave write start address is stored
* \param[in] InternalAddressLen Size of the internal device address, in bytes
* \param[in] Buffer Pointer to a buffer where the packet data to send is stored
* \param[in] Length Size of the packet to send, in bytes
*/
uint8_t TWI_WritePacket(const uint8_t SlaveAddress,
const uint8_t TimeoutMS,
const uint8_t* InternalAddress,
uint8_t InternalAddressLen,
const uint8_t* Buffer,
uint8_t Length);
/* Disable C linkage for C++ Compilers: */
#if defined(__cplusplus)

84
LUFA/Drivers/Peripheral/TWI.c
View file

@ -7,8 +7,8 @@
#include "TWI.h"
bool TWI_StartTransmission(const uint8_t SlaveAddress,
const uint8_t TimeoutMS)
uint8_t TWI_StartTransmission(const uint8_t SlaveAddress,
const uint8_t TimeoutMS)
{
for (;;)
{
@ -33,17 +33,17 @@ bool TWI_StartTransmission(const uint8_t SlaveAddress,
continue;
default:
TWCR = (1 << TWEN);
return false;
return TWI_ERROR_BusFault;
}
}
_delay_us(10);
}
if (!(BusCaptured))
if (!(TimeoutRemaining))
{
TWCR = (1 << TWEN);
return false;
return TWI_ERROR_BusCaptureTimeout;
}
TWDR = SlaveAddress;
@ -59,17 +59,85 @@ bool TWI_StartTransmission(const uint8_t SlaveAddress,
}
if (!(TimeoutRemaining))
return false;
return TWI_ERROR_SlaveResponseTimeout;
switch (TWSR & TW_STATUS_MASK)
{
case TW_MT_SLA_ACK:
case TW_MR_SLA_ACK:
return true;
return TWI_ERROR_NoError;
default:
TWCR = ((1 << TWINT) | (1 << TWSTO) | (1 << TWEN));
return false;
return TWI_ERROR_SlaveNotReady;
}
}
}
uint8_t TWI_ReadPacket(const uint8_t SlaveAddress,
const uint8_t TimeoutMS,
const uint8_t* InternalAddress,
uint8_t InternalAddressLen,
uint8_t* Buffer,
uint8_t Length)
{
uint8_t ErrorCode;
if ((ErrorCode = TWI_WritePacket(SlaveAddress, TimeoutMS, InternalAddress, InternalAddressLen,
NULL, 0)) != TWI_ERROR_NoError)
{
return ErrorCode;
}
if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_READ,
TimeoutMS)) == TWI_ERROR_NoError)
{
while (Length--)
{
if (!(TWI_ReceiveByte(Buffer++, (Length == 0))))
{
ErrorCode = TWI_ERROR_SlaveNAK;
break;
}
}
TWI_StopTransmission();
}
return ErrorCode;
}
uint8_t TWI_WritePacket(const uint8_t SlaveAddress,
const uint8_t TimeoutMS,
const uint8_t* InternalAddress,
uint8_t InternalAddressLen,
const uint8_t* Buffer,
uint8_t Length)
{
uint8_t ErrorCode;
if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_WRITE,
TimeoutMS)) == TWI_ERROR_NoError)
{
while (InternalAddressLen--)
{
if (!(TWI_SendByte(*(InternalAddress++))))
{
ErrorCode = TWI_ERROR_SlaveNAK;
break;
}
}
while (Length--)
{
if (!(TWI_SendByte(*(Buffer++))))
{
ErrorCode = TWI_ERROR_SlaveNAK;
break;
}
}
TWI_StopTransmission();
}
return ErrorCode;
}