[ATmega328] DS1307 RTC I2C(TWI)통신 1탄

직접 만든 DS1307 RTC모듈로 테스트 중입니다. ^^;

대부분의 RTC 모듈은 I2C로 동작합니다~~

일단 I2C로 동작하는 코드입니다.

RTC를 직접 셋팅하는 부분은 추후에 2탄으로 진행하겠습니다.

#define F_CPU   16000000    //Clock frequency
#define F_SCL   100000      //100kHz
#include <avr/io.h>
#include <util/twi.h> //header file
#include <util/delay.h> //header file
#include <avr/interrupt.h>
 
#define DS1307_R    0xD1
#define DS1307_W    0xD0
 
void i2c_init(void) {
    TWSR = 0;
    TWBR = ((F_CPU / F_SCL) - 16) / 2;      //100kHz
    TWCR = 0x04;                            //TWI Enable
}
 
int i2c_start(void) {
    TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN);
    while((TWCR & (1<<TWINT))==0);
    return 0;
}
 
int i2c_write(unsigned char data) {
    TWDR = data;
    TWCR = (1<<TWINT)|(1<<TWEN);
    while((TWCR & (1<<TWINT)) == 0);
    return 0;
}
 
unsigned char i2c_read() {
    TWCR = (1<<TWINT)|(1<<TWEN);
    while((TWCR & (1<<TWINT)) == 0);
    return TWDR;
}
 
int i2c_stop(void) {
    TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWSTO);
    return 0;
}
 
void i2c_putc() {
    i2c_start();
    i2c_write(DS1307_W);
    i2c_write(0x00);
    i2c_write(0x00);
    i2c_stop();
    _delay_us(5);
}
 
unsigned char i2c_getc(unsigned char addr) {
    i2c_start();
    i2c_write(DS1307_W);
    i2c_write(addr);
    i2c_start();
    i2c_write(DS1307_R);
    unsigned char data = i2c_read();
    i2c_stop();
    _delay_us(5);
 
    return data;
}
 
void Tx_Char(char Tdata) {
    while(!(UCSR0A & (1<<UDRE0)));
    UDR0 = Tdata;
}
 
void Tx_String(char *str) {
    while(*str) {
        Tx_Char(*str++);
    }
}
 
int main(void) {
    unsigned char yr, mh, da, hours, minutes, seconds;
    char str[30];
    UCSR0A = 0;
    UCSR0B = (1 << RXCIE0) | (1 << RXEN0) | (1 << TXEN0);    //RX INT EN, RX & TX Enable
    UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);                    //8bit no parity
    UBRR0H = 0;    UBRR0L = 8;     
    
    i2c_init();
    i2c_putc();
    while(1) {
        yr = i2c_getc(0x06);
        yr = ((yr>>4) & 0x0F)*10 + (yr & 0x0F);
        mh = i2c_getc(0x05);
        mh = ((mh>>4) & 0x01)*10 + (mh & 0x0F);
        da = i2c_getc(0x04);
        da = ((da>>4) & 0x03)*10 + (da & 0x0F);
        hours = i2c_getc(0x02);
        hours = ((hours>>4) & 0x07)*10 + (hours & 0x0F);
        minutes = i2c_getc(0x01);
        minutes = ((minutes>>4) & 0x07)*10 + (minutes & 0x0F);
        seconds = i2c_getc(0x00);
        seconds = ((seconds>>4) & 0x07)*10 + (seconds & 0x0F);
        
        sprintf(str, "%02d-%02d-%02d-%02d-%02d-%02d\r\n", yr+2000,mh,da,hours,minutes,seconds);
        Tx_String(str);
        _delay_ms(500);
    }
}