Time

I am not sure if you guys looked into the RTC library. You can use the DS1307 Real Time Clock breakout, you will need to install the library from GitHub to begin working with that.

https://github.com/adafruit/RTClib
https://www.adafruit.com/product/264

This is also the RTC library (https://www.arduino.cc/en/Reference/RTC) and it has some examples to start with.

Hey Stacy, Thanks for the link; such a great post. You are right that you can use the “millis” function. This is what I used in my project to see how much time has passed before sending sensor data. I have attached some of the snippet code on how I instantiated the millis object and keep track of the time. I think you also want to do something along those lines.

//initialize times
  gas_time = millis();
  flame_time = millis();
  pir_time = millis();
  sound_time = millis();
  temperature_time = millis();
  ultrasonic_time = millis();
 
  //PIR sensor
  pinMode(PirInput, INPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
  unsigned long time_passed = 0;
  
  //device #2
  //read gas sensor
  // don't read analog pins too often (<1Hz), else caps never get to charge.
 
  time_passed = millis() - gas_time;
 
  //if roll over, send next value again
  if (time_passed < 0)
  {
  gas_time = millis();
  gas_time_send = -700000;
  }

I hope that might be helpful. I am sure you also read their documentation but I am attaching the link (https://www.arduino.cc/reference/en/language/functions/time/millis/)