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@cosard
Last active Jan 30, 2021
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ds1302 avr library
#include "uart.h"
#include "rtc.c"
// Baud rate setting
#define BAUD 9600
void main(void) {
// Serial channel (9600, N,8,1)
uart_init((UART_BAUD_SELECT((BAUD),F_OSC)));
sei(); // interrupt enable
unsigned char sec, temp;
sec = 0;
struct rtc_time ds1302;
struct rtc_time *rtc;
rtc = &ds1302;
ds1302_init();
ds1302_update(rtc); // update all fields in the struct
ds1302_set_time(rtc, SEC, 31); //set the seconds to 31
while (1) // read seconds and send it via uart continuously
{
ds1302_update_time(rtc, SEC); //read the seconds
uart_putc(rtc->second); // send byte to serial line , you may not send it via uart,
uart_puts_P( "\r"); // LF // I just want to mention how to use the data with this
_delay_ms(100);
}
}
// rtc.c
// author COSAR DINDAR
// Date: November,23th 2012
#include <avr/interrupt.h>
#include <avr/io.h>
#include <stdio.h>
#include <stdbool.h>
#include <util/delay.h>
#include "rtc.h"
void ds1302_update_time(struct rtc_time * time, unsigned char field) // read time, field can be SEC, MIN, HOUR...
{
unsigned char temp;
ds1302_comms(time, field, 0, READ);
}
void ds1302_set_time(struct rtc_time * time, unsigned char field, unsigned char w_byte) // set time, field can be SEC, MIN, HOUR...
{ // w_byte can be the value you want to set
unsigned char temp;
ds1302_comms(time, field, w_byte, WRITE);
}
void ds1302_comms(struct rtc_time * time, unsigned char field, unsigned char write_byte, unsigned char rw)
{
unsigned char temp;
if(rw == READ)
{
if(field == SEC)
{
temp = ds1302_read_byte(sec_r);
time->second = ((temp & 0x0F) + ((temp & 0x70)>>4)*10);
}
else if(field == MIN)
{
temp = ds1302_read_byte(min_r);
time->minute = ((temp & 0x0F) + ((temp & 0x70)>>4)*10);
}
else if(field == HOUR)
{
temp = ds1302_read_byte(hour_r);
if(temp & 0x80 == 1) // 12 format
{
if(temp & 0x20 == 1) // PM
time->hour_format = PM;
else // AM
time->hour_format = AM;
time->hour = ((temp & 0x0F) + ((temp & 0x10)>>4)*10);
}
else // 24 format
{
time->hour_format = H24;
time->hour = ((temp & 0x0F) + ((temp & 0x30)>>4)*10);
}
}
else if(field == DAY)
{
temp = ds1302_read_byte(day_r);
time->day = (temp & 0x07);
}
else if(field == DATE)
{
temp = ds1302_read_byte(date_r);
time->date = ((temp & 0x0F) + ((temp & 0x30)>>4)*10);
}
else if(field == MONTH)
{
temp = ds1302_read_byte(month_r);
time->month = ((temp & 0x0F) + ((temp & 0x10)>>4)*10);
}
else if(field == YEAR)
{
temp = ds1302_read_byte(year_r);
time->minute = ((temp & 0x0F) + ((temp & 0xF0)>>4)*10);
}
}
else if(rw == WRITE)
{
if(field == SEC)
{
ds1302_write_byte(sec_w, (((write_byte/10)<<4) & 0x70 | (write_byte%10)));
}
else if(field == MIN)
{
ds1302_write_byte(min_w, (((write_byte/10)<<4) & 0x70 | (write_byte%10)));
}
else if(field == HOUR)
{
if(time->hour_format == AM)
ds1302_write_byte(hour_w, (((write_byte/10)<<4) & 0x10 | (write_byte%10)) | 0x80);
else if(time->hour_format == PM)
ds1302_write_byte(hour_w, (((write_byte/10)<<4) & 0x10 | (write_byte%10)) | 0xA0);
else if(time->hour_format == H24)
ds1302_write_byte(hour_w, ((((write_byte/10)<<4) & 0x30) | (write_byte % 10)));
}
else if(field == DAY)
{
ds1302_write_byte(day_w, write_byte & 0x03);
}
else if(field == DATE)
{
ds1302_write_byte(date_w, (((write_byte/10)<<4) & 0x30 | (write_byte%10)));
}
else if(field == MONTH)
{
ds1302_write_byte(month_w, (((write_byte/10)<<4) & 0x10 | (write_byte%10)));
}
else if(field == YEAR)
{
ds1302_write_byte(year_w, (((write_byte/10)<<4) & 0xF0 | (write_byte%10)));
}
}
}
void ds1302_update(struct rtc_time * time)
{
ds1302_update_time(time, SEC);
ds1302_update_time(time, MIN);
ds1302_update_time(time, HOUR);
ds1302_update_time(time, DAY);
ds1302_update_time(time, DATE);
ds1302_update_time(time, MONTH);
ds1302_update_time(time, YEAR);
}
void ds1302_init(void) // sets all pins as output and low
{
ds1302_PORT |= (1<<rst) | (1<<clk) | (1<<io);
clk_0(); // sclk -> 0
rst_0(); // rst -> 0
io_0(); // io -> 0
}
void ds1302_reset(void) //sets the pins to begin the ds1302 communication
{
clk_0(); // sclk -> 0
rst_0(); // rst -> 0
rst_1(); // rst -> 1
_delay_us(4);
}
unsigned char ds1302_read_byte(unsigned char w_byte) //read the byte with register w_byte
{
unsigned char temp;
ds1302_reset();
write(w_byte);
temp = read();
rst_0(); // finish transmittion
clk_0();
return temp;
}
void ds1302_write_byte(unsigned char w_byte, unsigned char w_2_byte) //write the byte with register w_byte
{
ds1302_reset();
write(w_byte);
write(w_2_byte);
rst_0(); // finish transmittion
clk_0();
}
void write(unsigned char W_Byte) //writes the W_Byte to the DS1302
{
unsigned char i;
ds1302_DDR |= (1<<io); // io as output -> 1
for(i = 0; i < 8; ++i)
{
io_0();
if(W_Byte & 0x01)
{
io_1();
}
clk_0();
_delay_us(2);
clk_1();
_delay_us(2);
W_Byte >>=1;
}
}
unsigned char read() //reads the ds1302 reply
{
unsigned char i, R_Byte, TmpByte;
R_Byte = 0x00;
ds1302_DDR &= ~(1<<io); // io as input -> 0
for(i = 0; i < 8; ++i) //get byte
{
clk_1();
_delay_us(2);
clk_0();
_delay_us(2);
TmpByte = 0;
if(bit_is_set(ds1302_PIN,io))
TmpByte = 1;
TmpByte <<= 7;
R_Byte >>= 1;
R_Byte |= TmpByte;
}
return R_Byte;
}
// rtc.c
// author COSAR DINDAR
// Date: November,23th 2012
#ifndef _RTC_H_
#define _RTC_H_
// ds1302 connection
#define ds1302_PORT PORTD
#define ds1302_DDR DDRD
#define ds1302_PIN PIND
#define rst 4
#define clk 6
#define io 7
#define rst_1() ds1302_PORT |= (1<<rst);
#define rst_0() ds1302_PORT &= ~ (1<<rst);
#define clk_1() ds1302_PORT |= (1<<clk);
#define clk_0() ds1302_PORT &= ~ (1<<clk);
#define io_1() ds1302_PORT |= (1<<io);
#define io_0() ds1302_PORT &= ~ (1<<io);
#define AM 10
#define PM 11
#define H24 12
#define READ 15
#define WRITE 16
#define mon 1
#define tue 2
#define wed 3
#define thu 4
#define fri 5
#define sat 6
#define sun 7
#define sec_w 0x80
#define sec_r 0x81
#define min_w 0x82
#define min_r 0x83
#define hour_w 0x84
#define hour_r 0x85
#define date_w 0x86
#define date_r 0x87
#define month_w 0x88
#define month_r 0x89
#define day_w 0x8a
#define day_r 0x8b
#define year_w 0x8c
#define year_r 0x8d
#define SEC 20
#define MIN 21
#define HOUR 22
#define DAY 22
#define DATE 23
#define MONTH 24
#define YEAR 25
#define w_protect 0x8e
struct rtc_time{
char second;
char minute;
char hour;
char day;
char date;
char month;
char year;
char hour_format;
};
void ds1302_update_time(struct rtc_time *, unsigned char);
void ds1302_set_time(struct rtc_time * time, unsigned char field, unsigned char w_byte);
void ds1302_comms(struct rtc_time *, unsigned char, unsigned char, unsigned char);
void ds1302_update(struct rtc_time *);
void ds1302_init (void); //ds1302 init
void ds1302_reset(void); //ds1302_reset
unsigned char ds1302_read_byte(unsigned char);
void ds1302_write_byte(unsigned char, unsigned char);
void write(unsigned char);
unsigned char read(void);
void ds1302_write_byte(unsigned char,unsigned char);
#endif
@SherifRagab
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SherifRagab commented May 16, 2015

Can I get the uart.h file please ?

@bronek999
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bronek999 commented Apr 14, 2016

This library have BUG.
between ds1302_reset and read or write must be delay 4uS. Datasheet page 9 AC Electrical charasteristics - RST to CLK setup.
Library works with 3V+ battery. But with low battery voltage it can read bad rtc result.

@cosard
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Author

cosard commented Mar 16, 2017

@bronek999 Thanks for the comment. I will edit it accordingly.

@blume1
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blume1 commented Mar 22, 2017

Hi Corsard!
Line #97 of rtc.c shall correctly be
ds1302_write_byte(hour_w, ((((write_byte/10)<<4) & 0x30) | (write_byte % 10)));

& 0x30 instead of & 0x10 is the difference.
Thanks for the lib, anyway! :)

@mianqi2016
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mianqi2016 commented Jan 30, 2021

Do you have an avr-libc library for LCD1602 ?

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