Abstract: This application note addresses how to convert the 32-bit time value into a date and time value that can be put in the form of MM/DD/YYYY, HH:MM:SS. An algorithm for converting from a date and time to binary seconds is also described. Introduction The DS1371 and DS1374 have a 32-bit binary counter RTC with a 2-wire interface. The 32-bit binary counters are designed to continuously count time in seconds. This application note addresses how to convert the 32-bit time value into a date and time value that can be put in the form of MM/DD/YYYY, HH:MM:SS. An algorithm for converting from a date and time to binary seconds is also described. Both devices accumulate time information in a 4-byte register as the number of seconds since some arbitrary reference date. The date used in this application note is the same used with the UNIX operating system, the reference date January 1, 1970, often referred to as Unix Epoch. Note: Because of the reference date used and the use of a 32-bit counter, this algorithm rolls over on Tuesday, January 19, 03:14:07, 2038. Binary Seconds to Date/Time Figure 1 shows the basic algorithm used to convert raw seconds to a date/time. Below is a C implementation of the algorithm. // AppNote517.cpp : Defines the entry point for the console application. // #include "stdafx.h" // this structure is just the local version of Visual C tm structure in time.h struct tm_struct { int tm_sec; /* seconds after the minute - [0,59] */ int tm_min; /* minutes after the hour - [0,59] */ int tm_hour; /* hours since midnight - [0,23] */ int tm_mday; /* day of the month - [1,31] */ int tm_mon; /* months since January - [0,11] */ int tm_year; /* years since 1900 */ int tm_wday; /* days since Sunday - [0,6] */ int tm_yday; /* days since January 1 - [0,365] */ int tm_isdst; /* daylight savings time flag */ // NOT USED }; // this array represents the number of days in one non-leap year at // the beginning of each month unsigned long DaysToMonth[13] = { 0,31,59,90,120,151,181,212,243,273,304,334,365 }; unsigned long DS1371_DateToBinary(tm_struct *datetime) { unsigned long iday; unsigned long val; iday = 365 * (datetime->tm_year - 70) + DaysToMonth[datetime->tm_mon] + (datetime->tm_mday - 1); iday = iday + (datetime->tm_year - 69) / 4; if ((datetime->tm_mon > 1) && ((datetime->tm_year % 4) == 0)) { iday++; } val = datetime->tm_sec + 60 * datetime->tm_min + 3600 * (datetime->tm_hour + 24 * iday); return val; } void DS1371_BinaryToDate(unsigned long binary,tm_struct *datetime) { unsigned long hour; unsigned long day; unsigned long minute; unsigned long second; unsigned long month; unsigned long year; unsigned long whole_minutes; unsigned long whole_hours; unsigned long whole_days; unsigned long whole_days_since_1968; unsigned long leap_year_periods; unsigned long days_since_current_lyear; unsigned long whole_years; unsigned long days_since_first_of_year; unsigned long days_to_month; unsigned long day_of_week; whole_minutes = binary / 60; second = binary - (60 * whole_minutes); // leftover seconds whole_hours = whole_minutes / 60; minute = whole_minutes - (60 * whole_hours); // leftover minutes whole_days = whole_hours / 24; hour = whole_hours - (24 * whole_days); // leftover hours whole_days_since_1968 = whole_days + 365 + 366; leap_year_periods = whole_days_since_1968 / ((4 * 365) + 1); days_since_current_lyear = whole_days_since_1968 % ((4 * 365) + 1); // if days are after a current leap year then add a leap year period if ((days_since_current_lyear >= (31 + 29))) { leap_year_periods++; } whole_years = (whole_days_since_1968 - leap_year_periods) / 365; days_since_first_of_year = whole_days_since_1968 - (whole_years * 365) - leap_year_periods; if ((days_since_current_lyear <= 365) && (days_since_current_lyear >= 60)) { days_since_first_of_year++; } year = whole_years + 68; // setup for a search for what month it is based on how many days have past // within the current year month = 13; days_to_month = 366; while (days_since_first_of_year < days_to_month) { month--; days_to_month = DaysToMonth[month]; if ((month >= 2) && ((year % 4) == 0)) { days_to_month++; } } day = days_since_first_of_year - days_to_month + 1; day_of_week = (whole_days + 4) % 7; datetime->tm_yday = days_since_first_of_year; /* days since January 1 - [0,365] */ datetime->tm_sec = second; /* seconds after the minute - [0,59] */ datetime->tm_min = minute; /* minutes after the hour - [0,59] */ datetime->tm_hour = hour; /* hours since midnight - [0,23] */ datetime->tm_mday = day; /* day of the month - [1,31] */ datetime->tm_wday = day_of_week; /* days since Sunday - [0,6] */ datetime->tm_mon = month; /* months since January - [0,11] */ datetime->tm_year = year; /* years since 1900 */ } int main(int argc, char* argv[]) { tm_struct timeStruct; unsigned long binary; printf("DS1371_DateToBinary and DS1371_BinaryToDate example:\n\n"); timeStruct.tm_hour = 17; timeStruct.tm_min = 32; timeStruct.tm_sec = 53; timeStruct.tm_year = 107; timeStruct.tm_mday = 21; timeStruct.tm_mon = 6; timeStruct.tm_wday = 4; binary = DS1371_DateToBinary(&timeStruct); printf("DS1371_DateToBinary(&timeStruct) where timeStruct = "); printf("%d:%d:%d, %d/%d/%d\n",timeStruct.tm_hour,timeStruct.tm_min,timeStruct.tm_sec, timeStruct.tm_mon,timeStruct.tm_mday,timeStruct.tm_year+1900); printf("\t\t\t\tbinary returned value = %d\n\n",binary); DS1371_BinaryToDate(binary,&timeStruct); printf("DS1371_BinaryToDate(binary,&timeStruct) where binary = %d\n",binary); printf("\t\t\t\ttimeStruct -> %d:%d:%d, %d/%d/%d\n",timeStruct.tm_hour,timeStruct.tm_min,timeStruct.tm_sec, timeStruct.tm_mon,timeStruct.tm_mday,timeStruct.tm_year+1900); printf("\ndone.\n"); /* Results of execution: DS1371_DateToBinary and DS1371_BinaryToDate example: DS1371_DateToBinary(&timeStruct) where timeStruct = 17:32:53, 6/21/2007 binary returned value = 1185039173 DS1371_BinaryToDate(binary,&timeStruct) where binary = 1185039173 timeStruct -> 17:32:53, 6/21/2007 done. */ return 0; } Figure 1. Binary to date algorithm flow. Date/Time to Binary Seconds Figure 2 shows the basic algorithm used to convert date/time to raw seconds. Below is a C implementation of the algorithm. unsigned long DS1371_DateToBinary(tm_struct *datetime) { unsigned long iday; unsigned long val; iday = 365 * (datetime->tm_year - 70) + DaysToMonth[datetime->tm_mon] + (datetime->tm_mday - 1); iday = iday + (datetime->tm_year - 69) / 4; if ((datetime->tm_mon > 1) && ((datetime->tm_year % 4) == 0)) { iday++; } val = datetime->tm_sec + 60 * datetime->tm_min + 3600 * (datetime->tm_hour + 24 * iday); return val;} Figure 2. Date to binary algorithm flow. Testing The C implementations used in this application note were thoroughly tested for each counter value over the 68-year span of the algorithm (from January 1, 1970 to January 18, 2038) and was found to be error free. 의견을 보내주세요! 위 내용이 도움이 되셨나요? 여러분의 의견을 기다립니다 — Maxim은 보내주신 정정이나 제안사항을 반영하고 있습니다. 이 페이지를 평가하고 의견을 보내주십시오. 자동 업데이트 관심있는 분야의 애플리케이션 노트가 나올 때 자동으로 업데이트 받고 싶으세요? 그렇다면 EE-Mail™을 신청하십시오. 추가 정보   APP 517: Mar 21, 2003 DS1318 병렬 인터페이스가 내장된 경과시간 카운터 전체 데이터 시트 (PDF, 168kB) 무료 샘플 DS1371 I²C, 32비트 바이너리 카운터 워치독 클록 전체 데이터 시트 (PDF, 1.2MB) 무료 샘플 DS1372 64비트 ID를 가진 I²C, 32비트, 바이너리 카운터 클록 전체 데이터 시트 (PDF, 176kB) 무료 샘플 DS1374 트리클 충전기 및 리셋 입/출력을 갖는 I²C 32비트 바이너리 카운터 워치독 RTC 전체 데이터 시트 (PDF, 320kB) 무료 샘플 DS1602 경과시간 카운터 전체 데이터 시트 (PDF, 224kB) DS1603 경과시간 카운터 모듈 전체 데이터 시트 (PDF, 232kB) DS1672 I²C 32비트 바이너리 카운터 RTC 전체 데이터 시트 (PDF, 552kB) 무료 샘플   다운로드, PDF 형식 (62kB)  AN517, AN 517, APP517, Appnote517, Appnote 517