1. simple 3-wire interface
2. Vcc = 5V and TTL-compatible
3. Optional industrial temperature range -40 to +85
4. Dual power tube for the main power and backup power supply
5. Wide range of operating voltage 2.0 5.5V
6. Current 2.0V, less than 300nA
7. 31 8 temporary data storage RAM
8. Serial I / O port pin makes the least number of ways
9. Read / write clock or RAM data transmission when there are two single-byte transmit and multi-byte character sets transfer mode
10. 8-pin DIP package or optional 8-pin SOIC package assembly according to the surface
Size : 44mmX23mmX1.6mm / 1.7”X0.9”/0.06” ( approach )
Working Temperature: 0℃~+70℃
Operating Voltage Range:3.3v ~ 5V
Note : Do not reverse VCC and GND, will it cause damage
It requires a pull-up resistor for P0 port of 51 MCU, if without, you can connect the data cable to other terminal
* 구입 : http://www.ebay.com/itm/200931981696?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
* 연결 : CR2032, CR2025 버튼형 리튬전지 차이점
* 참고
– http://www.instructables.com/id/Real-Time-Clock-DS1302/
– https://www.virtuabotix.com/virtuabotix-ds1302-real-time-clock-module-pin-out-coding-guide/
– Arduino Time library
– DS1302 Real Time Clock
Important note : Cheap modules with the DS1302 and DS1307 have often problems with the crystal and the voltage. They often don’t work very well. You are strongly advised to use a DS3231, which is very reliable and accurate and needs only a battery to run (the crystal is inside the DS3231).