RTC DS1302 Clock Module Note that this module does not use I2C communication. Interfacing the DS1302 with a microcontroller is done using a synchronous 3-wire serial communication.

Item Name: DS1302 Real Time Clock Module.
Color: Green
Material: PCB.
Weight: 0.28 oz (8 g).
Dimensions: 1.97 in x 0.98 in x 0.43 in (5*2.5*1.1cm)
Working temperature: 0°- 70°.
DS1302 work to maintain low power consumption data and clock information when power is less than 1mW.
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.
Simple 3-wire interface.
Serial I / O ports such a way that a minimum number of pins.
DS1302 real time clock module parameters are as follows:
PCB single panel, size: 44mm * 23mm * 1.6mm
With four positioning holes, diameter 3.1mm
Backup battery is genuine celestial CR2032, Voltage 3V, current 260mAh, non-rechargeable batteries.
Theoretical data retention time is more than 10 years!
DS1302 is made large 8-pin DIP chip, chip below IC socket for easy replacement and swap chips
Module operating voltage compatible 3.3V/5V, can be connected with 5V and 3.3V microcontroller

RTC DS1302 Clock Module About this:

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 3.3V/5.5V
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

1. Most RTCs use a crystal oscillator, but some have the option of using the power line frequency.
2. The crystal frequency is usually 32.768 kHz, the same frequency used in quartz clocks and watches.
3. Being exactly 2¹⁵ cycles per second, it is a convenient rate to use with simple binary counter circuits.
4. The low frequency saves power, while remaining above human hearing range.
5. The quartz tuning fork of these crystals does not change size much from temperature, so temperature does not change its frequency much.

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