View source for Real Time Clock RTC DS1307 Module

==DESCRIPTION==
[[File:DS1307.jpg]]

The DS1307 Serial Real-Time Clock is a low-power, full binary-coded decimal (BCD) clock/calendar
plus 56 bytes of NV SRAM.  Address and data are transferred serially via a 2-wire, bi-directional bus.
The clock/calendar provides seconds, minutes, hours, day, date, month, and year information.  The end of
the month date is automatically adjusted for months with fewer than 31 days, including corrections for
leap year.  The clock operates in either the 24-hour or 12-hour format with AM/PM indicator.  The
DS1307 has a built-in power sense circuit that detects power failures and automatically switches to the
battery supply.

==FEATURES==
*Real-time clock (RTC) counts seconds,minutes, hours, date of the month, month, daof the week, and year with leap-year compensation valid up to 2100
*56-byte, battery-backed, nonvolatile (NV) RAM for data storage
*Two-wire serial interface
*Programmable squarewave output signal
*Automatic power-fail detect and switch circuitry
*Consumes less than 500nA in battery backup mode with oscillator running
*Optional industrial temperature range:-40°C to +85°C
*Available in 8-pin DIP or SOIC Underwriters Laboratory (UL) recognized

==PIN DESCRIPTION==
VCC - Primary Power Supply

GND - Ground

SDA - Serial Data
SDA is the input/output pin for the 2-wire serial interface.  The SDA pin is open drain which requires an external pullup resistor.

SCL - Serial Clock 
SCL is used to synchronize data movement on the serial interface.

SQW/OUT (Square Wave/Output Driver) – When enabled, the SQWE bit set to 1, the SQW/OUT pin
outputs one of four square wave frequencies (1Hz, 4kHz, 8kHz, 32kHz).  The SQW/OUT pin is open
drain and requires an external pull-up resistor.  SQW/OUT will operate with either Vcc or Vbat applied.

X1, X2 - 32.768kHz Crystal Connection
– Connections for a standard 32.768kHz quartz crystal.  The internal oscillator circuitry is
designed for operation with a crystal having a specified load capacitance (CL) of 12.5pF.