RTC Interupt

Using Arduino Programming Questions
#1

Can some explain some code, so that if I wanted to output temperature using a thermistor onto an LCD every 3 seconds using a RTC with an interupt?

Currently Im using a mod (%) function and multiple if statements but I think that an interupt so that the arduino does the temperature function at regular intervals (3 seconds) would be far better

#2

What have you tried so far? What did you code?

How would you like the RTC to be read and an interrupt triggered? What else is connected in your project?

#3

This is one of my if statements

if(t.sec%10==0 && tempfunc()<30){ // Do this if statement when the time is at an interval of 10 sec AND the temp is less than 30 deg C run this function
lcd.setCursor(0,0); // Sets the location at which subsequent text written to the LCD will be displayed, first line, start
lcd.print("Temp: "); // Prints string “Temp: " on the LCD
lcd.print(tempfunc()); // Prints the distance value from the sensor using temperature function
lcd.print(” C "); // Prints string "C " on the LCD
}

I want an interupt to interupt my code and run the function below when the time is a multiple of 10 basically.

lcd.setCursor(0,0); // Sets the location at which subsequent text written to the LCD will be displayed, first line, start
lcd.print("Temp: "); // Prints string “Temp: " on the LCD
lcd.print(tempfunc()); // Prints the distance value from the sensor using temperature function
lcd.print(” C "); // Prints string "C " on the LCD
}

#4
  • the function I want to run is called:

void tempfuncnorm(){

#5

output temperature using a thermistor onto an LCD every 3 seconds

Why complicate things by using an interrupt ?

You will not be able to print to the LCD in the ISR because that uses interrupts and they are disabled when in an ISR. The best that you can do is to set a flag to indicate that 3 seconds has passed and respond to it in loop() so you might just as well test for 3 seconds elapsing in loop() (or a function called for it) in the first place

#6

I am required to run an interupt, it would be less complicated if I could do it my way.

You can defo program this, this way! I genuinely don't understand how the interupt function works, would you explain it to me, ignore the LCD etc. just treat that as a function, say LCDfunc and show me how an interrupt works please

#7

show me how an interrupt works please

When the interrupt occurs the program immediately stops what it is doing and runs the code in the Interrupt Service Routine . When that is finished the program returns to the place in the program where it was when the interrupt occurred and executes the next instruction after the one that it was executing when the ISR occurred

That is all there is to it

What don't you understand ?

#8

steve-unicorn:
I genuinely don't understand how the interupt function works, would you explain it to me

https://www.arduino.cc/reference/en/language/functions/external-interrupts/attachinterrupt/
You will connect, for example, the RTC PPS output to a digital input configured to read external interrupts. Then count 3 of those to create your 3 second delay.

If this is not a school assignment, don't do it this way. Just use millis().

#9

steve-unicorn:
I am required to run an interupt

Homework?

#10

gfvalvo:
Homework?

Which is it?
"I think that an interupt so that the arduino does the temperature function at regular intervals (3 seconds) would be far better"
or
"I am required to run an interupt"

#11