DS1307 RTC Module

RTC (Real Time Clock) module with I2C interface and 56 bytes of NV SRAM

RTC (Real Time Clock) module with I2C interface and 56 bytes of NV SRAM.

Pins

GND · ground

Ground

5V · power

Positive voltage (5V)

SDA · i2c

I2C data line

SCL · i2c

I2C clock line

SQW · output

Square wave output

The I2C address of the DS1307 is 0x68.

Attributes

initTime · string · default: "now"

Initial time of the RTC: “0”, “now”, or a valid ISO 8601 date string

Simulation Behavior

The simulated DS1307 is automatically initialized to the current system time when starting the simulation. It then keeps counting the time. You can override the initial time by setting the initTime attribute to a different value. The value can be either a valid ISO 8601 date string (e.g. “2019-11-19T11:41:56Z”), or one of the following special values:

• “0” - Set the initial time to “2000-01-01T00:00:00Z”
• “now” - Set the initial time to the current system time

“Z” at the end of the date string indicates that the time is in UTC, and not in the local time zone. If you omit the “Z”, the time will be interpreted as local time.

The code running in the simulation can update the date/time of the DS1307, and the DS1307 will keep track of the updated time.

Square Wave Output (SQW)

The SQW pin can output a square wave signal at one of four frequencies, or a static high/low level. Using the RTClib library, you can configure the SQW output with writeSqwPinMode():

Mode	Output
DS1307_OFF	LOW
DS1307_ON	HIGH
DS1307_SquareWave1HZ	1 Hz
DS1307_SquareWave4kHz	4.096 kHz
DS1307_SquareWave8kHz	8.192 kHz
DS1307_SquareWave32kHz	32.768 kHz

Example

To enable a 1 Hz square wave output:

#include <RTClib.h>

RTC_DS1307 rtc;

void setup() {
  rtc.begin();
  rtc.writeSqwPinMode(DS1307_SquareWave1HZ);
}

void loop() {
  // Your code here
}

Simulator examples

• Reading current date/time using RTClib
• Alarm clock