/* 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); }