Grove - RTC

Introduction

3.3V 5.0V I2C

The RTC module is based on the clock chip DS1307, which supports the I2C protocol. It utilizes a Lithium cell battery (CR1225). The clock/calendar provides seconds, minutes, hours, day, date, month, and year. The end of the month date is automatically adjusted for months with fewer than 31 days, including corrections for leap years. The clock operates in either the 24-hour or 12-hour format with AM/PM indicator. And it is valid up to 2100. In order to gain a robust performance, you must put a 3-Volt CR1225 lithium cell in the battery-holder. If you use the primary power only, the module may not work normally, because the crystal may not oscillate.

Note

The battery is not included.

Specifications

  • PCB Size: 2.0cm*4.0cm
  • Interface: 2.0mm pitch pin header
  • IO Structure: SCL,SDA,VCC,GND
  • ROHS: YES
  • VCC:3.3~5.5V
  • Logic High Level Input :2.2~VCC+0.3 V
  • Logic Low Level Input :-0.3~+0.8 V
  • Battery Voltage:2.0~3.5 V

Tip

More details about Grove modules please refer to Grove System

Platforms Supported

Demonstration

With Arduino

The following sketch demonstrates a simple application of setting the time and reading it out.

  • Connect the module to the I2C Interface of Grove- Base Shield.
  • Plug Grove- Base Shield into Arduino.
  • Connect Arduino to PC via a USB cable.
  • Download the RTC Library.
  • Unzip it into the libraries file of Arduino IDE by the path: ..\arduino-1.0\libraries.
  • Open the code directly by the path:File -> Example ->RTC->SetTimeAndDisplay.
    #include <Wire.h>
    #include "DS1307.h"

DS1307 clock;//define a object of DS1307 class
void setup()
{
    Serial.begin(9600);
    clock.begin();
    clock.fillByYMD(2013,1,19);//Jan 19,2013
    clock.fillByHMS(15,28,30);//15:28 30"
    clock.fillDayOfWeek(SAT);//Saturday
    clock.setTime();//write time to the RTC chip
}
void loop()
{
    printTime();
}
    /*Function: Display time on the serial monitor*/
void printTime()
{
    clock.getTime();
    Serial.print(clock.hour, DEC);
    Serial.print(":");
    Serial.print(clock.minute, DEC);
    Serial.print(":");
    Serial.print(clock.second, DEC);
    Serial.print("  ");
    Serial.print(clock.month, DEC);
    Serial.print("/");
    Serial.print(clock.dayOfMonth, DEC);
    Serial.print("/");
    Serial.print(clock.year+2000, DEC);
    Serial.print(" ");
    Serial.print(clock.dayOfMonth);
    Serial.print("*");
    switch (clock.dayOfWeek)// Friendly printout the weekday
    {
        case MON:
        Serial.print("MON");
        break;
        case TUE:
        Serial.print("TUE");
        break;
        case WED:
        Serial.print("WED");
        break;
        case THU:
        Serial.print("THU");
        break;
        case FRI:
        Serial.print("FRI");
        break;
        case SAT:
        Serial.print("SAT");
        break;
        case SUN:
        Serial.print("SUN");
        break;
    }
    Serial.println(" ");
}
  • Set the time. Put function arguments change to current date/time. The attention should be paid to the arguments format.
clock.fillByYMD(2013,1,19);//Jan 19,2013
clock.fillByHMS(15,28,30);//15:28 30"
clock.fillDayOfWeek(SAT);//Saturday
  • Upload the code.
  • Open the serial monitor to see the result.

The output time is changing like the clock.

With Raspberry Pi

1.You should have a raspberry pi and a grovepi or grovepi+.

2.You should have completed configuring the development enviroment, otherwise follow here.

3.Connection

  • Plug the sensor to grovepi socket i2c-x(1~3) by using a grove cable.

4.Navigate to the demos’ directory:

    cd yourpath/GrovePi/Software/Python/
  • To see the code
    nano grove_i2c_rtc.py   # "Ctrl+x" to exit #
    import time
    import grovepi

    # Connect the Grove Real Time Clock to any I2C port eg. I2C-1
    # Can be found at I2C address 0x68
    # SCL,SDA,VCC,GND

    while True:
        try:
            print grovepi.rtc_getTime()
            time.sleep(.5)

        except IOError:
            print "Error"

5.Run the demo.

    sudo python grove_i2c_rtc.py

6.Result

7.Use this demo to show the time in common

    '''
    /*
     * Grove-RTC.py
     * Demo for Raspberry Pi 
     *
     * Copyright (c) 2014 seeed technology inc.
     * Website    : www.seeed.cc
     * Author     : Lambor
     * Create Time: Nov 2014
     * Change Log :
     *
     * The MIT License (MIT)
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * all copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
     * THE SOFTWARE.
     */
    '''
    #!/usr/bin/python
    import time
    import smbus


    bus = smbus.SMBus(1)    # 0 = /dev/i2c-0 (port I2C0), 1 = /dev/i2c-1 (port I2C1)   

    class DS1307():     
        def __init__(self):
            self.MON = 1
            self.TUE = 2
            self.WED = 3
            self.THU = 4
            self.FRI = 5
            self.SAT = 6
            self.SUN = 7
            self.DS1307_I2C_ADDRESS = 0x68

            print 'begin' 

        def decToBcd(self, val):
            return ( (val/10*16) + (val%10) )

        def bcdToDec(self,  val):
            return ( (val/16*10) + (val%16) )

        def begin(self, news):
            print news

        def startClock(self):   
            bus.write_byte(self.DS1307_I2C_ADDRESS, 0x00)
            self.second = bus.read_byte(self.DS1307_I2C_ADDRESS) & 0x7f
            bus.write_byte_data(self.DS1307_I2C_ADDRESS, 0x00, self.second)

            print 'startClock..'

        def stopClock(self):                        
            bus.write_byte(self.DS1307_I2C_ADDRESS, 0x00)
            self.second = bus.read_byte(self.DS1307_I2C_ADDRESS) | 0x80
            bus.write_byte_data(self.DS1307_I2C_ADDRESS, 0x00, self.second)         

            print 'stopClock..'

        def setTime(self):
            data = [self.decToBcd(self.second), self.decToBcd(self.minute), \
                    self.decToBcd(self.hour), self.decToBcd(self.dayOfWeek), \
                    self.decToBcd(self.dayOfMonth), self.decToBcd(self.month), \
                    self.decToBcd(self.year)]

            bus.write_byte(self.DS1307_I2C_ADDRESS, 0x00)
            bus.write_i2c_block_data(self.DS1307_I2C_ADDRESS,0x00,data)

            print 'setTime..'

        def getTime(self):
            bus.write_byte(self.DS1307_I2C_ADDRESS, 0x00)
            data = bus.read_i2c_block_data(self.DS1307_I2C_ADDRESS,0x00)
            #A few of these need masks because certain bits are control bits
            self.second = self.bcdToDec(data[0] & 0x7f)
            self.minute = self.bcdToDec(data[1])
            self.hour = self.bcdToDec(data[2] & 0x3f)  #Need to change this if 12 hour am/pm
            self.dayOfWeek = self.bcdToDec(data[3])
            self.dayOfMonth = self.bcdToDec(data[4])
            self.month = self.bcdToDec(data[5])
            self.year = self.bcdToDec(data[6])

            print 'getTime..'

        def fillByHMS(self, _hour,  _minute,  _second):
            self.hour = _hour
            self.minute = _minute
            self.second = _second

            print 'fillByHMS..'

        def fillByYMD(self, _year,  _month,  _day):     
            self.year = _year - 2000
            self.month = _month;
            self.dayOfMonth = _day

            print 'fillByYMD..'

        def fillDayOfWeek(self,  _dow):     
            self.dayOfWeek = _dow

            print 'fillDayOfWeek..'

    if __name__ == "__main__": 
        clock = DS1307()
        clock.fillByYMD(2015,3,5)
        clock.fillByHMS(12,42,30)
        clock.fillDayOfWeek(clock.THU)  
        clock.setTime()
        while True:     
            clock.getTime()
            print clock.hour, ":", clock.minute, ":", \
                    clock.second, " ", clock.dayOfMonth, "/", \
                    clock.month, "/", clock.year,"  ", "weekday", \
                    ":", clock.dayOfWeek            
            time.sleep(1)

8.Create grove_rtc.py and copy codes above.

9.Run the code

    sudo python grove_rtc.py

10.Result

Resources


ArduinoWioBeagleBoneRaspberry PiLinkIt ONE

Caution

The platforms mentioned above as supported is/are an indication of the module's hardware or theoritical compatibility. We only provide software library or code examples for Arduino platform in most cases. It is not possible to provide software library / demo code for all possible MCU platforms. Hence, users have to write their own software library.

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Happy hacking