twi.h

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#ifndef TWI_H
#define TWI_H
 
/*
 * I2C/TWI library for AVR-GCC.
 * (c) 2018-2025 Tomas Fryza, MIT license
 *
 * Developed using PlatformIO and Atmel AVR platform.
 * Tested on Arduino Uno board and ATmega328P, 16 MHz.
 */

 
// -- Includes ---------------------------------------------
 #include <avr/io.h>
 
 
// -- Defines ----------------------------------------------
#ifndef F_CPU
#define F_CPU 16000000 
#endif
#define F_SCL 100000 
#define TWI_BIT_RATE_REG ((F_CPU/F_SCL - 16) / 2) 
 

#define TWI_PORT PORTC 
#define TWI_SDA_PIN 4 
#define TWI_SCL_PIN 5 
 

#define TWI_WRITE 0 
#define TWI_READ 1 
#define TWI_ACK 0 
#define TWI_NACK 1 
#define DDR(_x) (*(&_x - 1)) 
#define PIN(_x) (*(&_x - 2)) 
 
 
// -- Function prototypes ----------------------------------
void twi_init(void);
 

void twi_start(void);
 

uint8_t twi_write(uint8_t data);
 

uint8_t twi_read(uint8_t ack);
 

void twi_stop(void);
 

uint8_t twi_test_address(uint8_t addr);
 

void twi_readfrom_mem_into(uint8_t addr, uint8_t memaddr, volatile uint8_t *buf, uint8_t nbytes);

 
#endif