avr:balise

Besoin

ATTiny45

clignotement

par boucle

par interruption

mecanisme

implémentation

detection de nuit

analog comparator

référence interne

code par polling

int main (void)
{
   DDRB |= _BV(LED); // PBx as output
   
   // configure negative input of analog comparator as AIN1 (Cf p124)
   // default value
   ADCSRB &= ~ _BV(ACME);

   // activate AC (def value)
   ACSR &= ~ _BV(ACD);
   // Select internal 1.1V reference
   ACSR |= _BV(ACBG);

   // init done, blink a little
   blink_init(LED);
   
   while (1)
   {
      if ( bit_is_set(ACSR, ACO) ) {
         // ACO is set --> dark, switch on led
         // PORTB |= _BV(LED);
         blink(LED);
      }
      else {
         // ACO is not set --> light, switch off led
         PORTB &= ~ _BV(LED);
      }

   }

   return (0);
} /* main */

code par interruption

#define sOFF   0
#define sBLINK 1

volatile int state;

/** Set state from ACO
 * @return the state
 */
int setState (void)
{
   if (bit_is_set (ACSR,ACO))
      return sBLINK;
   else
      return sOFF;
}
/** Interrupt handler for Analog Comparator
 */
ISR(ANA_COMP_vect)
{
   state = setState();
}


/** MAIN
 */
int main (void)
{
   
   DDRB |= _BV(LED); // PBx as output
   // TODO: activate internal pull-up
   
   // configure negative input of analog comparator as AIN1 (Cf p124)
   // default value
   ADCSRB &= ~ _BV(ACME);

   // activate AC (def value)
   ACSR &= ~ _BV(ACD);
   // Select internal 1.1V reference
   ACSR |= _BV(ACBG);
   // Interrupt on AC output toggle
   ACSR &= ~ ( _BV(ACIS1) | _BV(ACIS0) );
   // Activate analog comparator interrupt
   ACSR |= _BV(ACIE);

   sei(); // enable global interrupts

   state = setState();
   
   // init done, blink a little
   blink_init(LED);
   
   while (1)
   {
      if ( state == sBLINK ) {
         // ACO is set --> dark, switch on led
//          PORTB |= _BV(LED);
         blink(LED);
      }
      else { // state == sOFF
         // ACO is not set --> light, switch off led
         PORTB &= ~ _BV(LED);
      }

   }

   return (0);
} /* main */

seuil réglable

implémentation

power management

présentation des sleep modes

autres trucs

• Power reduction Register (PRR) p39 pour desactiver des modules
  • timer1
  • timer0
  • USI : oui
  • ADC : desctive aussi AnalogComp
• disable ADC
• disable analog comparator (Idle, ADC noise reduction) et tout le temps si internal voltage
• brown-out detection
• internal voltahe (désactivé si inutilisé par BOD, AnalogComp ou ADC)
• watchdog timer
• port pins : cf p59
  • input
  • activate internal pull-up si non connectée
  • desctiver input buffers (DIDR0 p125)

comparaison de la conso

implémentation

conclusion

Liens

• Note d'application Atmel : http://www.avrfreaks.net/index.php?func=viewItem&item_id=63&module=Freaks%20Tools