Interrupt doesn't seem to be working... Did I mess up the coding?

Projects Programming
1

EDITED in response to first reply to clear up confusion.

So I am currently trying to code a simple setup for my Arduino Pro Mini (temporarily); there is a voltage input from a circuit board into Pin 3, which is one of 2 values: 1.3V or 4.2V.
However, the interrupts don't seem to trigger even when I use a raising edge when the voltage shifts from 1.3V to 4.2V. The last time I checked, If the voltage was below 1.7V it would be a LOW signal and I thought 4.2V would definitely be identified as a HIGH voltage... although I may be wrong.

Stuff I have done:
Replaced the interrupt with a digitalRead(3) --digitalRead seems to work, but interrupt doesn't
Probed the voltages on an oscilloscope AND Voltmeter to make sure the voltages are changing as intended

Currently I have an LED light attached to Pin 6 as a visual indicator that the trigger is working... it isn't.
I have commented out the digitalRead code for now, but I attached it as part of a comment for transparency. When I comment out the interrupt and uncomment the digitalRead, this setup works as intended. The code doesn't error... It just doesn't turn on the LED light ever, even when the voltage going into the interrupt changes

int circuit_power = 4;
int reading_input = 3;
int circuit_ground = 5;
volatile byte state = LOW;


void setup() {
  pinMode(circuit_power, OUTPUT);
  pinMode(reading_input, INPUT);
  pinMode(circuit_ground, OUTPUT);
  pinMode(6, OUTPUT);
  attachInterrupt(digitalPinToInterrupt(reading_input), pressure_alert,RISING);
  attachInterrupt(digitalPinToInterrupt(reading_input), testing, FALLING);
  digitalWrite(circuit_power, HIGH);
  digitalWrite(circuit_ground, LOW);
}

void loop() {
/*
  if (digitalRead(reading_input) == LOW){
    state = LOW;
  }
  else{
    state = HIGH;
  }
 */
  digitalWrite(6, state);
}

void pressure_alert(){
  state = HIGH;
}

void testing(){
  state = HIGH;
}
2

Perhaps uncommenting this section of code -

//  attachInterrupt(digitalPinToInterrupt(reading_input), pressure_alert,RISING);
//  attachInterrupt(digitalPinToInterrupt(reading_input), testing, FALLING);
3

I may have been unclear, so I edited the original post. I HAVE tested it with that particular section UNCOMMENTED. The results aren't any different.

4 
  attachInterrupt(digitalPinToInterrupt(reading_input), pressure_alert,RISING);
  attachInterrupt(digitalPinToInterrupt(reading_input), testing, FALLING);

Both those statements refer to the same pin (reading_input). I don't think you can do that. If you want to do different things on the RISING and FALLING edges of the same pin, you would have to specify CHANGE and then read the pin in the interrupt routine to figure out whether it was RISING or FALLING.

Pete

5

I don't think you can do that.

I know that you can't do that.

You can use CHANGE as the trigger, and then, in the ISR, determine the current state of the pin, which will tell you whether the change was from HIGH to LOW or from LOW to HIGH.