why my interrupt INT0 triggers the routine for INT1 [solved]

Projects Programming
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I faced the same issue. In my setup, two push buttons are connected to Arduino Uno pins 2 and 3 as explained at https://www.arduino.cc/en/Tutorial/Button (with 10kOhm pull down resistors).

The board is powered either from USB, or from a 9V battery. The behavior was the same.

Issue: When only a single one of the buttons is pressed, the serial monitor shows that both int0 and int1 are triggered.

I am aware that Serial should not appear in an ISR, but this was just for the issue demonstration.

void ISR_INT0_vect() { Serial.println("int0"); }
void ISR_INT1_vect() { Serial.println("int1"); }
void setup() {
  Serial.begin(9600);
  pinMode(2, INPUT); pinMode(3, INPUT);
  attachInterrupt(digitalPinToInterrupt(2), ISR_INT0_vect, RISING);
  attachInterrupt(digitalPinToInterrupt(3), ISR_INT1_vect, RISING);
}
void loop() {}

Thanks to MarkT, I solved the issue. The problem was caused by the "cross talk" between the two signal wires, which ran together for about 50cm (about 20 inches). As soon as I split the two signal wires apart, the issue disappeared. I will consider using the capacitors as suggested. Thanks!