Which Attiny84 pins are interrupt pins?

Projects Programming
1

Hello,

I have this simple test program which works on Arduino Uno, but is not working on Attiny84 when I transfer it there.

int buttonPin1 =1;     
int buttonPin2 =2; 
int ledPin = 6;    

void setup()
{
  pinMode(ledPin,OUTPUT); 
  attachInterrupt(buttonPin1, setDarkness, RISING);  
  attachInterrupt(buttonPin2, setDarkness2, RISING);  
}

void setDarkness ()
{ xBlink(7, 1);      // blink 7 times with 1 second interval
}

void setDarkness2 ()
{ xBlink(4, 1);     // blink 4 times with 1 second interval
}


void loop() 
{
xBlink(2, 2);      // blink 2 times with 2 second interval                
}                                     

void xBlink (int n, int xDelay)           
 {
 xDelay = xDelay*1000;              
 for (int i = 1; i < n+1; i++)
 {
    digitalWrite(ledPin,HIGH);  
    delay(xDelay);
    digitalWrite(ledPin,LOW);
    delay(xDelay);
 }
 }

I have two buttons connected to pin 12 and 11. Not sure if I got interrupt pin numbers right?

// +-/-+
// VCC 1| |14 GND
// 0 2| |13 10/A0
// 1 3| |12 9/A1
// RESET 4| |11 8/A2
// INT0 2 5| |10 7/A3
// 3/A7 6| |9 6/A4 SCK
// MOSI 4/A6 7| |8 5/A5 MISO
// +----+

2

The single external interrupt is on PB2 (PCINT10 / INT0 / OC0A / CKOUT) which is physical pin 5 / digital pin 2. It is labeled in your diagram as INT0.

Your sketch can never completely work on an ATtiny84 because it does not have the necessary peripherals.

3

OK, that what I was afraid of. But then I am confused why Attiny84 datasheet says this microcontroler has "Pin Change Interrupt on 12 Pins"?

4

Pin Change Interrupt != External Interrupt. (or Pin Change Interrupt ? External Interrupt if you prefer a more traditional symbol)

5

Yes, to use the language of the datasheet. But pin change interrupts are external to the MCU as well (as opposed to something like a timer interrupt which might be called an internal interrupt).

But I don't see how the sketch works even on an Uno. The first argument for attachInterrupt() is an interrupt number, not a pin number. For an Uno, the choices are 0 and 1.

The bigger question is why fool with interrupts just to read buttons. What would be wrong with polling them instead. I haven't thought through it (and don't intend to) but pin change interrupts could probably be used to detect button presses, but there will be some additional logic hoops to jump through.

6

OK, thanks folks for explanations. Indeed on Uno it would be 0 and 1 logical pins - forgot to change them back to Uno numbering.
Will look in the forums further now how to utilise pin change interrupts. I need them to change some parameters if interrupted by button press anywere in the main loop.