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/* Library made by: g4lvanix
* Github repository: https://github.com/g4lvanix/I2C-master-lib
*/
#include <avr/io.h>
#include <util/twi.h>
#include "i2c_master.h"
#define F_SCL 400000UL // SCL frequency
#define Prescaler 1
#define TWBR_val ((((F_CPU / F_SCL) / Prescaler) - 16 ) / 2)
void i2c_init(void)
{
TWBR = (uint8_t)TWBR_val;
}
uint8_t i2c_start(uint8_t address)
{
// reset TWI control register
TWCR = 0;
// transmit START condition
TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
// wait for end of transmission
while( !(TWCR & (1<<TWINT)) );
// check if the start condition was successfully transmitted
if((TWSR & 0xF8) != TW_START){ return 1; }
// load slave address into data register
TWDR = address;
// start transmission of address
TWCR = (1<<TWINT) | (1<<TWEN);
// wait for end of transmission
while( !(TWCR & (1<<TWINT)) );
// check if the device has acknowledged the READ / WRITE mode
uint8_t twst = TW_STATUS & 0xF8;
if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return 1;
return 0;
}
uint8_t i2c_write(uint8_t data)
{
// load data into data register
TWDR = data;
// start transmission of data
TWCR = (1<<TWINT) | (1<<TWEN);
// wait for end of transmission
while( !(TWCR & (1<<TWINT)) );
if( (TWSR & 0xF8) != TW_MT_DATA_ACK ){ return 1; }
return 0;
}
uint8_t i2c_read_ack(void)
{
// start TWI module and acknowledge data after reception
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
// wait for end of transmission
while( !(TWCR & (1<<TWINT)) );
// return received data from TWDR
return TWDR;
}
uint8_t i2c_read_nack(void)
{
// start receiving without acknowledging reception
TWCR = (1<<TWINT) | (1<<TWEN);
// wait for end of transmission
while( !(TWCR & (1<<TWINT)) );
// return received data from TWDR
return TWDR;
}
uint8_t i2c_transmit(uint8_t address, uint8_t* data, uint16_t length)
{
if (i2c_start(address | I2C_WRITE)) return 1;
for (uint16_t i = 0; i < length; i++)
{
if (i2c_write(data[i])) return 1;
}
i2c_stop();
return 0;
}
uint8_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length)
{
if (i2c_start(address | I2C_READ)) return 1;
for (uint16_t i = 0; i < (length-1); i++)
{
data[i] = i2c_read_ack();
}
data[(length-1)] = i2c_read_nack();
i2c_stop();
return 0;
}
uint8_t i2c_writeReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length)
{
if (i2c_start(devaddr | 0x00)) return 1;
i2c_write(regaddr);
for (uint16_t i = 0; i < length; i++)
{
if (i2c_write(data[i])) return 1;
}
i2c_stop();
return 0;
}
uint8_t i2c_readReg(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length)
{
if (i2c_start(devaddr)) return 1;
i2c_write(regaddr);
if (i2c_start(devaddr | 0x01)) return 1;
for (uint16_t i = 0; i < (length-1); i++)
{
data[i] = i2c_read_ack();
}
data[(length-1)] = i2c_read_nack();
i2c_stop();
return 0;
}
void i2c_stop(void)
{
// transmit STOP condition
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
}
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