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/*
Copyright (C) Dean Camera, 2010.
dean [at] fourwalledcubicle [dot] com
www.fourwalledcubicle.com
*/
#include "TWI.h"
bool TWI_StartTransmission(uint8_t SlaveAddress, 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 false;
}
}
_delay_us(10);
}
if (!(BusCaptured))
{
TWCR = (1 << TWEN);
return false;
}
TWDR = SlaveAddress;
TWCR = ((1 << TWINT) | (1 << TWEN));
TimeoutRemaining = (TimeoutMS * 100);
while (TimeoutRemaining--)
{
if (TWCR & (1 << TWINT))
break;
_delay_us(10);
}
if (!(TimeoutRemaining))
return false;
switch (TWSR & TW_STATUS_MASK)
{
case TW_MT_SLA_ACK:
case TW_MR_SLA_ACK:
return true;
default:
TWCR = ((1 << TWINT) | (1 << TWSTO) | (1 << TWEN));
return false;
}
}
}
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