/* Tiny I2C

   David Johnson-Davies - www.technoblogy.com - 14th April 2018

   CC BY 4.0
   Licensed under a Creative Commons Attribution 4.0 International license:
   http://creativecommons.org/licenses/by/4.0/
*/

#ifndef TinyI2CMaster_h
#define TinyI2CMaster_h

#include <stdint.h>
#include <avr/io.h>
#include <util/delay.h>

// ATTiny84 specifics

/* #define DDR_USI_CL          DDR_USI */
/* #define DDR_USI             DDRB */

/* #define PORT_USI_SDA        PORTB0 */
/* #define PORT_USI_SCL        PORTB2 */
/* #define PORT_USI_CL         PORT_USI */
/* #define PORT_USI            PORTB */

/* #define PIN_USI_SDA         PINB0 */
/* #define PIN_USI_SCL         PINB2 */
/* #define PIN_USI_CL          PIN_USI */
/* #define PIN_USI             PINB */

// ATTiny24 specifics
#define DDR_USI_CL DDR_USI
#define DDR_USI DDRA

#define PORT_USI_SDA PORTA6
#define PORT_USI_SCL PORTA4
#define PORT_USI_CL PORT_USI
#define PORT_USI PORTA

#define PIN_USI_SCL PINA4
#define PIN_USI_SDA PINA6
#define USI_START_VECTOR USI_START_vect
#define USI_OVERFLOW_VECTOR USI_OVF_vect
#define PIN_USI_CL PIN_USI
#define PIN_USI PINA

// Defines
#define TWI_FAST_MODE

#ifdef TWI_FAST_MODE                 // TWI FAST mode timing limits. SCL = 100-400kHz
#define DELAY_T2TWI (_delay_us(2))   // >1.3us
#define DELAY_T4TWI (_delay_us(1))   // >0.6us
#else                                // TWI STANDARD mode timing limits. SCL <= 100kHz
#define DELAY_T2TWI (_delay_us(5))   // >4.7us
#define DELAY_T4TWI (_delay_us(4))   // >4.0us
#endif

#define TWI_NACK_BIT 0 // Bit position for (N)ACK bit.

void i2c_init(void);
uint8_t i2c_read(void);
uint8_t i2c_readLast(void);
uint8_t i2c_write(uint8_t data);
uint8_t i2c_start(uint8_t address, int8_t readcount);
void i2c_stop(void);

static int8_t I2Ccount;
uint8_t transfer(uint8_t data);

#endif