Arduino Micro Cannot get Interrupt 6 work on PIN 7

Question

After finding out about the situation with pin7 from this tutorial:

https://forum.sparkfun.com/viewtopic.php?f=32&t=35847

 void setup(){
 EICRB |= (1<<ISC60)|(0<<ISC61); // sets the interrupt type for EICRB (INT6).
 // EICRA sets interrupt type for INT0...3
 /*
 ISCn0 ISCn1 Where n is the interrupt. 0 for 0, etc
 0 0 Triggers on low level
 1 0 Triggers on edge
 0 1 Triggers on falling edge
 1 1 Triggers on rising edge
 */
EIMSK |= (1<<INT6); // activates the interrupt. 6 for 6, etc
void loop(){
//do other things here
}
ISR(INT6_vect) {
 // interrupt code goes here
 }

I have set:

EICRB |= (0<<ISC60)|(0<<ISC61);

Because I need it to be triggered on LOW.

I could still not get it work on the micro. IF I use the pin as regular input pin I can clearly see LOW/HIGHs on pin 7 with digitalread.

I have a sensor attached there which goes LOW in case it is triggered.

I wonder if anybody knows what else can I try to get it work. I already hardwired everything in my circuit board, there are no more free interrupts and no way to change them.

• Ignacio Vazquez-Abrams: ORing with 0 does nothing.
• Ignacio Vazquez-Abrams: And did you define an ISR?

Answer 1

I've used following code and loopback from pin 8 to pin 7:

// loopback: pin 8 -> pin 7
void setup() {
 pinMode(7, INPUT_PULLUP);
 pinMode(8, OUTPUT);
 pinMode(LED_BUILTIN_TX, OUTPUT); // to see pin 8 logic level on TX led
 pinMode(LED_BUILTIN, OUTPUT); // toggled by ISR
 EICRB |= _BV(ISC60); // Triggers on edge
 EIMSK |= _BV(INT6); // activates the interrupt
}
ISR(INT6_vect) {
 PINC = _BV(PC7); // toggle led 13 (@ PC7)
}
void loop() {
 digitalWrite(8, HIGH);
 digitalWrite(LED_BUILTIN_TX, HIGH);
 delay(500);
 digitalWrite(8, LOW);
 digitalWrite(LED_BUILTIN_TX, LOW);
 delay(500);
} 

And it works perfectly. Only problem I can imagine is to figure out correctly which pin is really 7 as label is on the right side of pin (not under nor left).