I2CBase.cpp

#include "I2cbase.h"
#include <avr/io.h>

uint8_t I2C_Error;

void I2C_Init() {
	TWCR = _BV(TWEA) | _BV(TWEN);
	I2C_SetBusSpeed(I2CBUSCLOCK / 100);
}

void I2C_Start() {
	TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);
	I2C_WaitForComplete();
	if ((TW_STATUS != TW_START) && (TW_STATUS != TW_REP_START)) I2C_SetError(I2C_STARTError);
}

void I2C_SendAddr(uint8_t address) {
	uint8_t Status;
	if ((address & 0x01) == 0) Status = TW_MT_SLA_ACK;
	else Status = TW_MR_SLA_ACK;
	TWDR = address;
	TWCR = _BV(TWINT) | _BV(TWEN);
	I2C_WaitForComplete();
	if (TW_STATUS != Status) I2C_SetError(I2C_NoACK);
	else I2C_SetError(I2C_OK);
}

void I2C_SendByte(uint8_t byte) {
	TWDR = byte;
	TWCR = _BV(TWINT) | _BV(TWEN);
	I2C_WaitForComplete();
	if (TW_STATUS != TW_MT_DATA_ACK) I2C_SetError(I2C_NoACK);
}

uint8_t I2C_ReceiveData_ACK() {
	TWCR = _BV(TWEA) | _BV(TWINT) | _BV(TWEN);
	I2C_WaitForComplete();
	if (TW_STATUS != TW_MR_DATA_ACK) I2C_SetError(I2C_NoACK);
	return TWDR;
}

uint8_t I2C_ReceiveData_NACK() {
	TWCR = _BV(TWINT) | _BV(TWEN);
	I2C_WaitForComplete();
	if (TW_STATUS != TW_MR_DATA_NACK) I2C_SetError(I2C_NoNACK);
	return TWDR;
}

void I2C_SetBusSpeed(uint16_t speed) {
	speed = (F_CPU / speed / 100 - 16) / 2;
	uint8_t prescaler = 0;
	while (speed > 255)
	{
		prescaler++;
		speed = speed / 4;
	};
	TWSR = (TWSR & (_BV(TWPS1) | _BV(TWPS0))) | prescaler;
	TWBR = speed;
}

void I2C_SendStartAndSelect(uint8_t addr) {
	I2C_Start();
	I2C_SendAddr(addr);
}