Features:
DS1302 real time clock module
DALLAS DS1302 is the company launched trickle charge the clock chip, which contains a real-time clock / calendar and 31 bytes of static RAM, via a simple serial interface to communicate with the microcontroller. Real-time clock / calendar circuit provides seconds, minutes, hours, days, weeks, months, years of information, the number of days per month and leap year automatically adjust the number of days. Clock operation by AM / PM indicator decided to use 24 or 12 hour format. DS1302 between the microcontroller can simply adopt the way synchronous serial communication port only used three lines: (1) RST Reset (2) I / O data lines (3) SCLK Serial Clock. Clock / RAM read / write data in a byte or up to 31 bytes of character set type communication. DS1302 work to maintain low power consumption data and clock information when power is less than 1mW

DS1302 key performance indicators:

Real-time clock with energy calculations before 2100 seconds, minutes, hours, day, week, month, year capacity, as well as the ability to leap year adjustment
serial I / O ports such a way that a minimum number of pins
Wide operating voltage range 2.0 5.5V
2.0V, operating current of less than 300nA
Read / write clock or RAM data transfer mode, there are two single-byte and multi-byte transfer mode transmission character set
8-pin DIP package or an optional 8-pin SOIC surface mount package under
Simple 3-wire interface
Vcc = 5V and TTL compatible
Optional industrial temperature range of -40 to +85
Dual power tubes used for the main power supply and backup power supply

DS1302 real time clock module parameters are as follows:

1. PCB single panel, size: 44mm * 23mm * 1.6mm
2. With four positioning holes, diameter 3.1mm
3. Backup battery is genuine celestial CR2032, Voltage 3V, current 260mAh, non-rechargeable batteries. Theoretical data retention time is more than 10 years!
4. Crystal 32.768KHz, Japan imported crystal, matching capacitance 6pF, size 2 * 6mm
5. DS1302 is made large 8-pin DIP chip, chip below IC socket for easy replacement and swap chips
6. Module operating voltage compatible 3.3V/5V, can be connected with 5V and 3.3V microcontroller
7. Working temperature: 0°--- 70°
8. 4.3x 2.3cm

Wiring methods (procedures in order to provide an example, you can access any IO port, modify the port definition in the program can be):

VCC → +5 V/3.3V
GND → GND
CLK → P02
DAT → P01
RST → P00

Note:
1. VCC and GND Do not reversed, it would burn the chip
2. C51 MCU P0 port requires pull-up resistor, if your device does not have a pull-up resistor can be connected to other ports data lines