AVR ds1302 RTC library

ds1302.cpp

#include "ds1302.h"
#include <avr/io.h>
#include <util/delay.h>

void ds1302_write(unsigned char cmd)
{
	DS1302_CE_DDR |= (1<<DS1302_CE_PNUM);
	DS1302_SCLK_DDR |= (1<<DS1302_SCLK_PNUM);
			
	DS1302_CE_PORT |= (1<<DS1302_CE_PNUM);

	_delay_us(4);
			
	DS1302_IO_DDR |= (1<<DS1302_IO_PNUM);
	for(unsigned char i=0; i<8; i++)
	{
		if((cmd&(1<<i)) == 1<<i)
		{
			DS1302_IO_PORT |= (1<<DS1302_IO_PNUM);
		}
		else
		{
			DS1302_IO_PORT &= ~(1<<DS1302_IO_PNUM);
		}

		DS1302_SCLK_PORT |= (1<<DS1302_SCLK_PNUM);
		_delay_us(1);
		DS1302_IO_PORT &= ~(1<<DS1302_IO_PNUM);
		DS1302_SCLK_PORT &= ~(1<<DS1302_SCLK_PNUM);
	}
}
		
unsigned char ds1302_read()
{
	unsigned char readbyte=0;
	DS1302_IO_DDR &= ~(1<<DS1302_IO_PNUM);
			
	for(unsigned char i=0; i<8; i++)
	{
		DS1302_SCLK_PORT |= (1<<DS1302_SCLK_PNUM);
				
		if((DS1302_IO_PIN & (1<<DS1302_IO_PNUM))==0)
		{
			readbyte &= ~(1<<i);
		}
		else
		{
			readbyte |= 1<<i;
		}
		_delay_us(10);
		DS1302_SCLK_PORT &= ~(1<<DS1302_SCLK_PNUM);
		_delay_us(2);
	}
	DS1302_CE_PORT &= ~(1<<DS1302_CE_PNUM);
	_delay_us(4);
	return readbyte;
}

unsigned char ds1302_read_byte(unsigned char byte_r)
{
	ds1302_write(byte_r);
	return ds1302_read();
}
		
void ds1302_write_byte(unsigned char byte_w, unsigned char val)
{
	ds1302_write(byte_w);
	ds1302_write(val);
	DS1302_CE_PORT &= ~(1<<DS1302_CE_PNUM);
}

void ds1302_rw(Ds1302_operation oper, Ds1302_register reg, Ds1302_rtc_time &rtc_time)
{
	unsigned char byte;
	
	if(oper == READ){
		switch(reg){
			case CH:
				byte = ds1302_read_byte(DS1302_SEC_R);
				rtc_time.ch = byte & 0b10000000;
				break;
			case SEC:
				byte = ds1302_read_byte(DS1302_SEC_R);
				rtc_time.sec = (byte & 0b00001111) + ((byte>>4) & 0b00000111) * 10;
				break;
			case MIN:
				byte = ds1302_read_byte(DS1302_MIN_R);
				rtc_time.min = (byte & 0b00001111) + ((byte>>4) & 0b00000111) * 10;
				break;
			case HOUR:
				byte = ds1302_read_byte(DS1302_HOUR_R);
				rtc_time.hour.mode12h = (byte & 0b10000000);
				if(rtc_time.hour.mode12h)
				{
					rtc_time.hour.pm = (byte & 0b00100000);
					rtc_time.hour.hour = (byte & 0b00001111) + ((byte>>4) & 0b00000001) * 10;
				}
				else
				{
					rtc_time.hour.hour = (byte & 0b00001111) + ((byte>>4) & 0b00000011) * 10;
				}
				break;
			case DATE:
				byte = ds1302_read_byte(DS1302_DATE_R);
				rtc_time.date = (byte & 0b00001111) + ((byte>>4) & 0b00000011) * 10;
				break;
			case MONTH:
				byte = ds1302_read_byte(DS1302_MONTH_R);
				rtc_time.month = (byte & 0b00001111) + ((byte>>4) & 0b00000001) * 10;
				break;
			case DAY:
				byte = ds1302_read_byte(DS1302_DAY_R);
				rtc_time.day = byte & 0b00000111;
				break;
			case YEAR:
				byte = ds1302_read_byte(DS1302_YEAR_R);
				rtc_time.year = (byte & 0b00001111) + ((byte>>4) & 0b00001111) * 10;
				break;
			case WP:
				byte = ds1302_read_byte(DS1302_WP_R);
				rtc_time.wp = byte & 0b10000000;
				break;
		}
	} else { //WRITE
		switch(reg){
			case CH:
				byte = ds1302_read_byte(DS1302_SEC_R);
				if(rtc_time.ch){
					byte |= 0b10000000;
				} else {
					byte &= 0b01111111;
				}
				ds1302_write_byte(DS1302_SEC_W, byte);
				break;
			case SEC:
				//preserve CH bit value
				byte = ds1302_read_byte(DS1302_SEC_R) & 0b10000000;
				byte |= (((rtc_time.sec/10)<<4) & 0b01110000) | (rtc_time.sec%10);
				ds1302_write_byte(DS1302_SEC_W, byte);
				break;
			case  MIN:
				ds1302_write_byte(DS1302_MIN_W, (((rtc_time.min/10)<<4) & 0b01110000) | (rtc_time.min%10));
				break;
			case HOUR:
				if(rtc_time.hour.mode12h){
					byte = 0b10000000 | (((rtc_time.hour.hour/10)<<4) & 0b00010000) | (rtc_time.hour.hour%10);
					if(rtc_time.hour.pm) byte |= 0b00100000;
				} else {
					byte = (((rtc_time.hour.hour/10)<<4) & 0b00110000) | (rtc_time.hour.hour%10);
				}
				ds1302_write_byte(DS1302_HOUR_W, byte);
				break;
			case DATE:
				ds1302_write_byte(DS1302_DATE_W, (((rtc_time.date/10)<<4) & 0b00110000) | (rtc_time.date%10));
				break;
			case MONTH:
				ds1302_write_byte(DS1302_MONTH_W, (((rtc_time.month/10)<<4) & 0b00010000) | (rtc_time.month%10));
				break;
			case DAY:
				ds1302_write_byte(DS1302_DAY_W, rtc_time.day & 0b00000111);
				break;
			case YEAR:
				ds1302_write_byte(DS1302_YEAR_W, (((rtc_time.year/10)<<4) & 0b11110000) | (rtc_time.year%10));
				break;
			case  WP:
				ds1302_write_byte(DS1302_WP_W, rtc_time.wp ? 0b10000000 : 0b00000000);
				break;
		}
	}
}

ds1302.h

#ifndef DS1302_H_
#define DS1302_H_

#define F_CPU 8000000 //8MHz

#define DS1302_CE_PIN PIND
#define DS1302_CE_DDR DDRD
#define DS1302_CE_PORT PORTD
#define DS1302_CE_PNUM 5

#define DS1302_IO_PIN PIND
#define DS1302_IO_DDR DDRD
#define DS1302_IO_PORT PORTD
#define DS1302_IO_PNUM 6

#define DS1302_SCLK_PIN PIND
#define DS1302_SCLK_DDR DDRD
#define DS1302_SCLK_PORT PORTD
#define DS1302_SCLK_PNUM 7

#define DS1302_SEC_W 0x80
#define DS1302_SEC_R 0x81
#define DS1302_MIN_W 0x82
#define DS1302_MIN_R 0x83
#define DS1302_HOUR_W 0x84
#define DS1302_HOUR_R 0x85
#define DS1302_DATE_W 0x86
#define DS1302_DATE_R 0x87
#define DS1302_MONTH_W 0x88
#define DS1302_MONTH_R 0x89
#define DS1302_DAY_W 0x8a
#define DS1302_DAY_R 0x8b
#define DS1302_YEAR_W 0x8c
#define DS1302_YEAR_R 0x8d
#define DS1302_WP_W 0x8e
#define DS1302_WP_R 0x8f
#define DS1302_TRICKLE_CHARGE_W 0x90
#define DS1302_TRICKLE_CHARGE_R 0x91
#define DS1302_CLOCK_BURST_W 0xbe
#define DS1302_CLOCK_BURST_R 0xbf
#define DS1302_RAM_BURST_W 0xfe
#define DS1302_RAM_BURST_R 0xff

typedef struct {
	unsigned char hour;
	bool pm;
	bool mode12h;
} Ds1302_hour;

typedef struct {
	bool ch;
	unsigned char sec;
	unsigned char min;
	Ds1302_hour hour;
	unsigned char date;
	unsigned char month;
	unsigned char day;
	unsigned char year;
	bool wp;
} Ds1302_rtc_time;

enum Ds1302_operation {READ, WRITE};
	
enum Ds1302_register {CH, SEC, MIN, HOUR, DATE, MONTH, DAY, YEAR, WP};

void ds1302_write(unsigned char cmd);
unsigned char ds1302_read();
unsigned char ds1302_read_byte(unsigned char byte_r);
void ds1302_write_byte(unsigned char byte_w, unsigned char val);
void ds1302_rw(Ds1302_operation oper, Ds1302_register reg, Ds1302_rtc_time &rtc_time);

#endif /* DS1302_H_ */

sample.cpp

#include "ds1302.h"

Ds1302_rtc_time rtc_time;

//read
ds1302_rw(READ, YEAR, rtc_time);
ds1302_rw(READ, MONTH, rtc_time);
ds1302_rw(READ, DATE, rtc_time);

//write
rtc_time.year = 15;
rtc_time.month = 7;
rtc_time.date = 25;
ds1302_rw(WRITE, YEAR, rtc_time);
ds1302_rw(WRITE, MONTH, rtc_time);
ds1302_rw(WRITE, DATE, rtc_time);