ATtiny85 External Interrupt to get out of Sleep Mode

Hi all,

I’m super new to hardware so forgive me for my ignorance :confused:

I’m trying to make something similar to Durr http://skreksto.re/products/durr. It is using the ATtiny85 (http://www.hobbytronics.co.uk/datasheets/ATTINY85.pdf) and I’m using an Arduino Uno as an ISP. It requires a vibration motor to turn on and off every five minutes, I’m using a watchdog timer to interrupt which is working fine. I also would like to turn the device on and off so I’m using an external interrupt.

But when I turn the device off and put it into sleep mode, it will not turn back on using the interrupt.

I have tried using an attachInterrupt and I didn’t get any better results. I think my main issue is understanding the sleep library.

I’ve taken the code from various places it is a bit of a hack job. Any help is appreciated! Thanks c:

// ATMEL ATTINY 25/45/85 / ARDUINO
//
//                  +-\/-+
// Ain0 (D 5) PB5  1|    |8  Vcc
// Ain3 (D 3) PB3  2|    |7  PB2 (D 2) Ain1   #SWITCH
// Ain2 (D 4) PB4  3|    |6  PB1 (D 1) pwm1 
//            GND  4|    |5  PB0 (D 0) pwm0   #LED
//                  +----+

#include <avr/sleep.h>
#include <avr/power.h>
#include <avr/wdt.h>
  

int countr; // WDT count
volatile unsigned int interruptedCount = 0; // INT0 count

const byte LED = 0;  // pin 5
const byte SWITCH = 2; // pin 7 / PCINT2

ISR(WDT_vect) {
  countr++;
 }
 
ISR(PCINT0_vect) {
  if (interruptedCount >= 2) {
    interruptedCount = 0;
    digitalWrite(LED, LOW);
    sleep_mode();
    // sleepsies
  } else {
    delay(10);
    if (digitalRead(SWITCH) == HIGH) {
        interruptedCount++; // debounce
    }
  }
 }

void setup(){
  pinMode(LED, OUTPUT);
  pinMode(SWITCH, INPUT);
  setup_watchdog(6);
  set_sleep_mode (SLEEP_MODE_IDLE);
  sleep_enable();
}

void loop() 
{
  if (countr > 1){ // set to 1 second for testing purposes || 299
    countr = 0;
    digitalWrite(0, HIGH);
    delay(1000);
    digitalWrite(0, LOW);
  }
}

void setup_watchdog(int timerPrescaler) {

  if (timerPrescaler > 9 ) timerPrescaler = 9; //Limit incoming amount to legal settings

  byte bb = timerPrescaler & 7; 
  if (timerPrescaler > 7) bb |= (1<<5); //Set the special 5th bit if necessary

  //This order of commands is important and cannot be combined
  MCUSR &= ~(1<<WDRF); //Clear the watch dog reset
  WDTCR |= (1<<WDCE) | (1<<WDE); //Set WD_change enable, set WD enable
  WDTCR = bb; //Set new watchdog timeout value
  WDTCR |= _BV(WDIE); //Set the interrupt enable, this will keep unit from resetting after each int
  
  PCMSK  = bit (PCINT2); // want pin D4 / pin 3
  GIFR  |= bit (PCIF); // clear any outstanding interrupts
  GIMSK |= bit (PCIE); // enable pin change interrupts 
}

I don't think an Attiny can be woken with an external interrupt. See section 9.2 of the datasheet compared to the equivalent section in the Atmega328 datasheet.

...R

Robin2: I don't think an Attiny can be woken with an external interrupt.

It does not matter. @hicough is using pin change interrupts which will wake the processor.

Hi,

hicough: But when I turn the device off and put it into sleep mode, it will not turn back on using the interrupt.

set_sleep_mode (SLEEP_MODE_IDLE);

You have misdiagnosed the problem. With Idle mode, the processor will wake the next time the millis timer overflows (approximately every 1ms). In other words, there will be a very short pause at the end of setup while the processor takes a nap and then loop will run.