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/*
Copyright (C) Dean Camera, 2011.
dean [at] fourwalledcubicle [dot] com
www.lufa-lib.org
*/
#define __INCLUDE_FROM_TWI_C
#include "TWI.h"
uint8_t TWI_StartTransmission(const uint8_t SlaveAddress,
const uint8_t TimeoutMS)
{
for (;;)
{
bool BusCaptured = false;
uint16_t TimeoutRemaining;
TWCR = ((1 << TWINT) | (1 << TWSTA) | (1 << TWEN));
TimeoutRemaining = (TimeoutMS * 100);
while (TimeoutRemaining-- && !(BusCaptured))
{
if (TWCR & (1 << TWINT))
{
switch (TWSR & TW_STATUS_MASK)
{
case TW_START:
case TW_REP_START:
BusCaptured = true;
break;
case TW_MT_ARB_LOST:
TWCR = ((1 << TWINT) | (1 << TWSTA) | (1 << TWEN));
continue;
default:
TWCR = (1 << TWEN);
return TWI_ERROR_BusFault;
}
}
_delay_us(10);
}
if (!(TimeoutRemaining))
{
TWCR = (1 << TWEN);
return TWI_ERROR_BusCaptureTimeout;
}
TWDR = SlaveAddress;
TWCR = ((1 << TWINT) | (1 << TWEN));
TimeoutRemaining = (TimeoutMS * 100);
while (TimeoutRemaining--)
{
if (TWCR & (1 << TWINT))
break;
_delay_us(10);
}
if (!(TimeoutRemaining))
return TWI_ERROR_SlaveResponseTimeout;
switch (TWSR & TW_STATUS_MASK)
{
case TW_MT_SLA_ACK:
case TW_MR_SLA_ACK:
return TWI_ERROR_NoError;
default:
TWCR = ((1 << TWINT) | (1 << TWSTO) | (1 << TWEN));
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;
}
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