Hi,
I have been building a data logger and have it running on a bare bones Arduino - it goes to sleep and is woken by an interrupt from a DS3231 to take a measurement from a voltage divider. That works successfully and I am now trying to replicate the same functionality on a MKR 1010, currently on a breadboard. I have attached photos below (I have an external pull-up resistor between VCC and pin 7 though I did not need one on the bare bones Arduino).
I am trying to get the external interrupt working when the alarm goes off however I find that the interrupt triggers sporadically and not every minute as expected. A capture of the output from the serial monitor is below;
11:37:44.404 -> Turn off alarms initially
11:37:44.444 -> Set alarm clock time
11:37:44.444 -> Turn on alarm
11:37:44.444 -> Attach pin interrupt
11:37:44.444 -> Pin interrupt attached on 7
11:38:02.643 -> 2020/5/31,10:38,0.0010,26.75
11:39:02.670 -> 2020/5/31,10:39,0.0010,26.75
11:43:02.670 -> 2020/5/31,10:43,0.0010,26.50
11:45:02.657 -> 2020/5/31,10:45,0.0015,26.50
11:50:02.660 -> 2020/5/31,10:50,0.0015,26.25
11:51:02.637 -> 2020/5/31,10:51,0.0015,26.25
11:52:02.654 -> 2020/5/31,10:52,0.0015,26.25
11:53:02.679 -> 2020/5/31,10:53,0.0015,26.25
11:55:02.640 -> 2020/5/31,10:55,0.0015,26.25
11:59:02.670 -> 2020/5/31,10:59,0.0010,26.25
Steps to investigate are;
- Tried different DS3231 RTC - didn't resolve
- Changed jumper wire from SQW pin to MKR 1010 (bad connection?) - didn't resolve
- Tried running RTC on 3.3V - didn't resolve
- Tried on pins A0 and 0 separately - didn't resolve
- I have been testing on pins A1 and 0 while RTC has been powered at 5V. Tried running on pin 7 with RTC only at 3.3V - didn't resolve
- Put 4.7k ohm pull up resistor between VCC and 7 - didn't resolve
- Put 10k ohm pull up resistor between VCC and 7 - didn't resolve
I can't work out where the problem is though. I have added my code below but I am getting the feeling this is related to the external pull up resistors, my understanding is that I need one to keep the pin high as the interupt is triggered when the SQW signal is falling.
At the moment though I can't figure it out so any suggestions would be gratefully received.
Many thanks.
#include <DS3231.h> //v1.0.2 https://github.com/NorthernWidget/DS3231
#include <Wire.h>
DS3231 Clock;
bool Century = false;
bool h12; s
bool PMT;
//byte ADay, AHour, AMinute, ASecond, ABits;
//bool ADy, A12h, APMT;
#define ALRM1_MATCH_EVERY_SEC 0b1111 // once a second
#define ALRM1_MATCH_SEC 0b1110 // when seconds match
//#define ALRM1_MATCH_MIN_SEC 0b1100 // when minutes and seconds match
//#define ALRM1_MATCH_HR_MIN_SEC 0b1000 // when hours, minutes, and seconds match
byte ALRM1_SET = ALRM1_MATCH_SEC;
//Variables for voltage calculation START
int value = 0;
int var;
int loops = 5;
float voltage;
const float referenceVoltage = 1;
//Variables for voltage calculation END
//Variables for RTC START
byte timeComponent, clockYear, clockMonth, clockDay,
clockHour, clockMinute;
//const byte rtcTimerIntPin = 3;
const float kelvin = 273.15;
bool alarmflag = false;
//Variables for RTC END
void setup() {
// Start the I2C interface
Wire.begin();
// Start the serial interface
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB
}
Serial.println("Turn off alarms initially");
Clock.turnOffAlarm(1);
Clock.turnOffAlarm(2);
Serial.println("Set alarm clock time");
Clock.setA1Time(0, 0, 0, 1, ALRM1_SET, true, false, false);
Serial.println("Turn on alarm");
Clock.turnOnAlarm(1);
Serial.println("Attach pin interrupt");
// Attach interrupt
pinMode (7, INPUT_PULLUP);
digitalWrite(7, HIGH);
attachInterrupt (digitalPinToInterrupt (7), clockTrigger, FALLING);
Serial.println(F("Pin interrupt attached on 7"));
}
void loop() {
// send what's going on to the serial monitor.
//if (alarmflag = true)
if (Clock.checkIfAlarm(1))
{
Clock.checkIfAlarm(1);
var = 0;
while (var < loops) {
value = value + analogRead(A1);
delay(5);
var++;
}
value = value / loops;
float temperature;
temperature = ((Clock.getTemperature()) / 4);
voltage = value * referenceVoltage / 2046; //1023;
//calculate voltage reading
clockYear = Clock.getYear();
delay(10);
clockMonth = Clock.getMonth(Century);
delay(10);
clockDay = Clock.getDate();
delay(10);
clockHour = Clock.getHour(h12, PMT);
delay(10);
clockMinute = Clock.getMinute();
delay(10);
// Start with the year
Serial.print("20");
Serial.print(clockYear);
Serial.print("/");
// then the month
//extraZero(clockMonth);
Serial.print(clockMonth);
Serial.print("/");
// then the date
//extraZero(clockDay);
Serial.print(clockDay);
Serial.print(",");
// Finally the hour, minute, and second
//extraZero(clockHour);
Serial.print(clockHour);
Serial.print(":");
//extraZero(clockMinute);
Serial.print(clockMinute);
// Display the temperature
Serial.print(",");
Serial.print(voltage, 4);
Serial.print(",");
Serial.println(Clock.getTemperature(), 2);
}
}
void extraZero(byte value)
{
if (value < 10) {
Serial.print("0");
}
}
void clockTrigger()
{
//don't do any other processing in this subroutine
}
