how to "digitalPinToInterrupt" ?

Projects General Guidance
1

Hi everyone
Can please someone guide me. I am trying to do a countdown time with a 4 digit 7 segment display.

When i click on the button the timer starts, when it finishes the display turns blank. It should start to contdown when i click the button again, but it does not.
what i am doing wrong ?

thanks

#include "SevSeg.h"
SevSeg sevseg; //Instantiate a seven segment controller object
const byte buttonPin = 2;
volatile int buttonPressed = 0;
volatile unsigned long lastButtonPress = 0;

static unsigned long timer = millis();
static int deciSeconds = 2000; 
int timerActive = 0;

void setup() {
  byte numDigits = 4;
  byte digitPins[] = {1, 7, 8, 9};
  byte segmentPins[] = {A0, A1, A2, A3, A4, A5, 6,4};
  bool resistorsOnSegments = false; // 'false' means resistors are on digit pins
  byte hardwareConfig = COMMON_ANODE; // See README.md for options
  bool updateWithDelays = false; // Default. Recommended
  bool leadingZeros = false; // Use 'true' if you'd like to keep the leading zeros
  
  sevseg.begin(hardwareConfig, numDigits, digitPins, segmentPins, resistorsOnSegments, updateWithDelays, leadingZeros);
  sevseg.setBrightness(90);
  

  sevseg.blank();
  attachInterrupt(digitalPinToInterrupt(buttonPin), buttonPressInterrupt, CHANGE);
  pinMode(buttonPin, INPUT_PULLUP);
}

void loop() {
  
  if(buttonPressed) {
    if (deciSeconds == 2000) {
       timerActive = 1;
    }
    buttonPressed = 0;
    timer = millis();
  }
  
  if (timerActive && millis() >= timer) {
    deciSeconds--; 
    timer += 100; 
    if (deciSeconds == 10000) { // Reset to 0 after counting for 1000 seconds.
      deciSeconds=0;
    }
    if (deciSeconds == 1999) 
    { 
      deciSeconds=1599;
    }
    if (deciSeconds == 999) 
    { 
      deciSeconds=599;
    }

    sevseg.setNumber(deciSeconds, 1);
 
  }
  
  if (deciSeconds == 0) 
  { 
    timerActive = 0;
    deciSeconds == 2000;
    buttonPressed = 1;
    sevseg.blank();
  }
  sevseg.refreshDisplay(); // Must run repeatedly
  
}

void buttonPressInterrupt() {
  if (millis() - lastButtonPress >= 300) {
    buttonPressed = 1;
    lastButtonPress = millis();
  }
}
2

If the button is wired to ground (as it should be), with pin 2 external interrupts, it would make better sense to use LOW instead of CHANGE here:

  attachInterrupt(digitalPinToInterrupt(buttonPin), buttonPressInterrupt, CHANGE);
  pinMode(buttonPin, INPUT_PULLUP);
5

No don't use LOW. That will keep firing the interrupt over and over and over as long as the pin is LOW. For a one shot use FALLING.

Sorry, that is what I meant.