Example Code for Arduino-Alarm Trigger Interrupt
Last revision 2025/12/19
This article provides example code for using the INT pin on an Arduino clock module to determine alarm triggers, with guidance on connecting the INT pin to the main control board's interrupt pin, specifically using Arduino UNO's D2 pin.
Hardware Preparation
- DFR0216-2 DFRduino UNO R3 with IO Expansion Shield and USB Cable A-B x 1
- DFR0819 Fermion: DS3232 RTC Module x 1
- FIT0916-FF DuPont Wires x5
Software Preparation
- Download Arduino IDE: Click to download Arduino IDE
- Download the DFRobot_DS323X library: DFRobot_DS323X library
- About how to install the library?
Wiring Diagram
Ensure the INT pin is connected to the correct interrupt pin of the main control board (D2 for UNO).
Sample Code
/*!
* @file setAlarmInterrupt.ino
* @brief Set alarm, and use interrput pin to trigger it
* @n Experiment phenomenon: set the alarm clock to trigger at a specified time
* @n connect int pin with DIGITALPIN2
* @n print information on serial port after the alarm clock is triggered.
* @copyright Copyright (c) 2010 DFRobot Co.Ltd (http://www.dfrobot.com)
* @licence The MIT License (MIT)
* @author [LuoYufeng]([email protected])
* @version V0.1
* @date 2021-2-23
* @url https://github.com/DFRobot/DFRobot_DS323X
*/
#include "DFRobot_DS323X.h"
volatile int8_t alarmFlag = 0;
DFRobot_DS323X rtc;
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 eSquareWave_OFF = 0x1C // Not output square wave, enter interrupt mode
*@n eSquareWave_1Hz = 0x00 // 1Hz square wave
*@n eSquareWave_1kHz = 0x08 // 1kHz square wave
*@n eSquareWave_4kHz = 0x10 // 4kHz square wave
*@n eSquareWave_8kHz = 0x18 // 8kHz square wave
*/
rtc.writeSqwPinMode(rtc.eSquareWave_OFF);
/*!
*@brief enable Alarm1 interrupt
*/
rtc.enableAlarm1Int();
/*!
*@brief disable Alarm1 interrupt
*/
//rtc.disableAlarm1Int();
/*!
*@brief enable Alarm2 interrupt
*/
rtc.enableAlarm2Int();
/*!
*@brief disable Alarm2 interrupt
*/
//rtc.disableAlarm2Int();
/*!
*@brief Set alarm clock
*@param alarmType Alarm clock working mode typedef enum{
*@n eEverySecond, //repeat in every second
*@n eSecondsMatch, //repeat in every minute
*@n eSecondsMinutesMatch, //repeat in every hour
*@n eSecondsMinutesHoursMatch, //repeat in every day
*@n eSecondsMinutesHoursDateMatch,//repeat in every month
*@n eSecondsMinutesHoursDayMatch, //repeat in every week //Alarm1
*@n eUnknownAlarm1
*@n }eAlarm1Types_t;
*@param days Alarm clock Day (day)
*@param hours Alarm clock Hour (hour)
*@param minutes Alarm clock Minute (minute)
*@param seconds Alarm clock Second (second)
*/
rtc.setAlarm1(rtc.eSecondsMatch,/*date,0-31*/1,/*hour,0-23*/0,/*minute,0-59*/0,/*second,0-59*/10);//Alarm1
/*!
*@brief Set alarm clock
*@param alarmType Alarm clock working mode typedef enum{
*@n eEveryMinute, //repeat in every minute
*@n eMinutesMatch, //repeat in every hour
*@n eMinutesHoursMatch, //repeat in every day
*@n eMinutesHoursDateMatch, //repeat in every month
*@n eMinutesHoursDayMatch, //repeat in every week //Alarm2
*@n eUnknownAlarm2
*@n }eAlarm2Types_t;
*@param days Alarm clock Day (day)
*@param hours Alarm clock Hour (hour)
*@param minutes Alarm clock Minute (minute)
*/
rtc.setAlarm2(rtc.eEveryMinute,/*date,0-31*/1,/*hour,0-23*/0,/*minute,0-59*/0);//Alarm2
/*!
*@brief Judge if it is power-down
*@return if return true, power-down, time needs to reset; false, work well
*/
if (rtc.isLostPower())
rtc.setTime(/*year,1900-2099*/2021, /*mouth,1-12*/2, /*date,1-31*/28, /*hour,0-23*/23,/*minute,0-59*/59,/*second,0-59*/55);//Set Set initial time .
#if defined(ESP32) || defined(ESP8266)||defined(ARDUINO_SAM_ZERO)
attachInterrupt(digitalPinToInterrupt(D6)/*Query the interrupt number of the D6 pin*/,interrupt,FALLING);
#else
/* The Correspondence Table of AVR Series Arduino Interrupt Pins And Terminal Numbers
* ---------------------------------------------------------------------------------------
* | | DigitalPin | 2 | 3 | |
* | Uno, Nano, Mini, other 328-based |--------------------------------------------|
* | | Interrupt No | 0 | 1 | |
* |-------------------------------------------------------------------------------------|
* | | Pin | 2 | 3 | 21 | 20 | 19 | 18 |
* | Mega2560 |--------------------------------------------|
* | | Interrupt No | 0 | 1 | 2 | 3 | 4 | 5 |
* |-------------------------------------------------------------------------------------|
* | | Pin | 3 | 2 | 0 | 1 | 7 | |
* | Leonardo, other 32u4-based |--------------------------------------------|
* | | Interrupt No | 0 | 1 | 2 | 3 | 4 | |
* |--------------------------------------------------------------------------------------
*/
/* The Correspondence Table of micro:bit Interrupt Pins And Terminal Numbers
* ---------------------------------------------------------------------------------------------------------------------------------------------
* | micro:bit | DigitalPin |P0-P20 can be used as an external interrupt |
* | (When using as an external interrupt, |---------------------------------------------------------------------------------------------|
* |no need to set it to input mode with pinMode)|Interrupt No|Interrupt number is a pin digital value, such as P0 interrupt number 0, P1 is 1 |
* |-------------------------------------------------------------------------------------------------------------------------------------------|
*/
attachInterrupt(/*Interrupt No*/0,interrupt,FALLING);//Open the external interrupt 0, connect INT1/2 to the digital pin of the main control:
//UNO(2), Mega2560(2), Leonardo(3), microbit(P0).
#endif
}
void loop() {
Serial.print(rtc.getYear(), DEC);
Serial.print('/');
Serial.print(rtc.getMonth(), DEC);
Serial.print('/');
Serial.print(rtc.getDate(), DEC);
Serial.print(" (");
Serial.print(rtc.getDayOfWeek());
Serial.print(") ");
Serial.print(rtc.getHour(), DEC);
Serial.print(':');
Serial.print(rtc.getMinute(), DEC);
Serial.print(':');
Serial.print(rtc.getSecond(), DEC);
Serial.print(' ');
/*if rtc works in 24hours mode,this function doesn't print anything*/
Serial.print(rtc.getAMorPM());
Serial.println();
if(alarmFlag == 1){
alarmFlag = 0;
Serial.println("Alarm clock is triggered.");
delay(1000);
rtc.clearAlarm();
}
else
delay(1000);
if (rtc.isLostPower()) {
Serial.println("RTC lost power, please reset the time!");
}
}
void interrupt(){
alarmFlag = 1;
}
Result
The serial port prints time information and alarm trigger information.
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