Example Code for Arduino-Low Power Consumption and Awake

Hardware Preparation

• DFR0216-2 DFRduino UNO R3 with IO Expansion Shield and USB Cable A-B x 1
• DFR0641 DS3231M MEMS Precise RTC Module x 1
• FIT0916-FF DuPont Wires x5

Software Preparation

• Download Arduino IDE: Click to download Arduino IDE
• Download the DFRobot_DS3231M library: DFRobot DS3231M library
• About how to install the library?

Wiring Diagram

Other Preparation Work

• Install the DS3231M Library in Arduino IDE.
• Connect the DS3231M module's INT pin to the Arduino UNO R3's interrupt pin D2.
• Connect other pins as per the Wiring Diagram.

Sample Code

    /*!
     * @file lowPowerAndWakeUp.ino
     * @brief Set alarm, and use interrput pin to trigger MCU wake up
     * @n Experiment phenomenon: Set the alarm clock to trigger at a specified time.
     * @n                        Connect SQW pin with DIGITALPIN2.
     * @n                        Print information on serial port after the alarm clock is triggered.
     * @n                        This demo only works on avr
     * @copyright	Copyright (c) 2010 DFRobot Co.Ltd (https://www.dfrobot.com)
     * @licence     The MIT License (MIT)
     * @author [LuoYufeng]([email protected])
     * @version  V0.1
     * @date  2019-08-19
     * @url https://github.com/DFRobot/DFRobot_DS3231M
     */
    #include "DFRobot_DS3231M.h"
    #include <avr/sleep.h>
    
    volatile  int8_t alarmFlag = 0;
    
    DFRobot_DS3231M rtc;
    int t = 0;
    
    void setup(void)
    {
        Serial.begin(9600);
        /*Wait for the chip to be initialized completely, and then exit*/
        while(rtc.begin() != true){
            Serial.println("failed to init chip, please check if the chip connection is correct. ");
            delay(1000);
        }
        /*!
         *@brief Set the value of pin sqw
         *@param mode eDS3231M_OFF             = 0x01 // Not output square wave, enter interrupt mode
         *@n          eDS3231M_SquareWave_1Hz  = 0x00 // 1Hz square wave
         *@n          eDS3231M_SquareWave_1kHz = 0x08 // 1kHz square wave
         *@n          eDS3231M_SquareWave_4kHz = 0x10 // 4kHz square wave
         *@n          eDS3231M_SquareWave_8kHz = 0x18 // 8kHz square wave
         */
        rtc.writeSqwPinMode(eDS3231M_OFF);
        rtc.enAbleAlarm1Int();
        //rtc.disAbleAlarm1Int();
        rtc.enAbleAlarm2Int();
        //rtc.disAbleAlarm2Int();
        /*!
         *@brief Set alarm clock 
         *@param alarmType Alarm clock working mode typedef enum{
         *@n                                  eEverySecond,
         *@n                                  eSecondsMatch,
         *@n                                  eSecondsMinutesMatch,
         *@n                                  eSecondsMinutesHoursMatch,
         *@n                                  eSecondsMinutesHoursDateMatch,
         *@n                                  eSecondsMinutesHoursDayMatch, //Alarm1
         *@n                                  eEveryMinute,
         *@n                                  eMinutesMatch,
         *@n                                  eMinutesHoursMatch,
         *@n                                  eMinutesHoursDateMatch,
         *@n                                  eMinutesHoursDayMatch,        //Alarm2
         *@n                                  eUnknownAlarm
         *@n                                  }eAlarmTypes;
         *@param days    Alarm clock (day)
         *@param hours   Alarm clock (hour)
         *@param mode:   e24hours, eAM, ePM
         *@param minutes Alarm clock (minute)
         *@param seconds Alarm clock (second)
         */
        rtc.setAlarm(eSecondsMatch,/*date,0-30*/29,/*hour,1-12 in 12hours,0-23 in 24hours*/9,e24hours,/*minute,0-59*/10,/*second,0-59*/40);
        
        rtc.setYear(19);//Set year, default in the 21st century. 
        rtc.setMonth(9);
        rtc.setDate(29);
        /*!
         *@brief Set the hours and 12hours or 24hours
         *@param hour:1-12 in 12hours,0-23 in 24hours
         *@param mode:e24hours, eAM, ePM
         */
        rtc.setHour(9,e24hours);
        rtc.setMinute(10);
        rtc.setSecond(30);
        rtc.adjust();
        attachInterrupt(0, interrupt, FALLING);
        
        /*!
         *@brief Set avr sleep mode
         */
        set_sleep_mode (SLEEP_MODE_PWR_DOWN);
        sleep_cpu();
        sleep_enable();
        
    }
    void loop() {
        /*!
         *@brief Judge if the alarm clock is triggered
         *@return true, triggered; false, not triggered
         */
        if(alarmFlag == 1){
            Serial.println("Alarm is up");
            rtc.clearAlarm();
            alarmFlag = 0;
            while (t < 10){
                rtc.getNowTime();
                Serial.print(rtc.year(), DEC);
                Serial.print('/');
                Serial.print(rtc.month(), DEC);
                Serial.print('/');
                Serial.print(rtc.day(), DEC);
                Serial.print(" (");
                Serial.print(rtc.getDayOfTheWeek());
                Serial.print(") ");
                Serial.print(rtc.hour(), DEC);
                Serial.print(':');
                Serial.print(rtc.minute(), DEC);
                Serial.print(':');
                Serial.print(rtc.second(), DEC);
                Serial.print(' ');
                /*if rtc works in 24hours mode,this function doesn't print anything*/
                Serial.print(rtc.getAMorPM());
                Serial.println();
                delay(1000);
                t = t + 1;
            }
            t = 0;
        }
        else
            delay(1000);
        /*!
         *@brief Judge if it is power-down 
         *@return if return true, power-down, time needs to reset; false, work well
         */
        if (rtc.lostPower()) {
            Serial.println("RTC lost power, please reset the time!");
        }
        sleep_enable();
        //energy.PowerDown();
    }
    
    
    void interrupt(){
        alarmFlag = 1;
        sleep_disable();
    }

Result

UNO enters sleep mode and is awakened by the RTC module at the specified time, then outputs time information.

Additional Information

NOTE: Note: Please connect the pin INT of sensor to the interrupt pin of maincontrol board(here selected D2 of UNO).