Operácie

AVR Example T1 counter

Z SensorWiki

Tento program pouzije D5 (arduino) ako pocitadlo. Mozne pripojit tlacitko, alebo 555 a pocitat pocet impulzov.

Vstavany terminal Arduina nema formatovanie, takze treba pouzit iny terminal aby sa to pekne vypisovalo:

#define SWITCH 5                // select the pin for Switch

void setup()
{
 pinMode(SWITCH, INPUT);        // this pin is an INPUT
  TCNT1 = 0x00;                 // initialize (CLEAR)counter 
 TCCR1B = 0x07;                 // T1 clk = external clock source on pin T1, rising edge

 Serial.begin(9600);
 Serial.println("Button test:");
}

void loop()                      // endless loop
{
 Serial.print("Input D5 = ");
 Serial.print(digitalRead(SWITCH),BIN);
 Serial.print("  TCNT1 = ");
 Serial.print(TCNT1,DEC);
 Serial.print('\r');             // this will not work with embedded Serial Monitor,  
                                 // but works fine with e.g. putty terminal

 delay(250);                     // wait 1/4s for another measurement
}


AVR Timer T1 Counter.png


AVR Timer TCNT1 Counter.png


Nasledovny kus programu nastavi pocitadlo na 5 impulzov pred pretecenim (0xFFFF - 5) a potom sleduje v hlavnej slucke, kedy nastane pretecenie. Ako hodinky je pouzity externy signal na T1, cize tlacitko alebo 555.

/* Example 9.2. Timer counter 1 in timer mode - pooled version  */

#define SWITCH 5      // Arduino D5, ATmega328 PD.5
#define LED 13        // Arduino D13, ATmega328 PB.5 

int ledState = LOW;         // variable used to store the last LED status, to toggle the light

void setup()                    // run once, when the sketch starts
{
  /* *********************** Init device ************************************ */

 pinMode(SWITCH, INPUT);        // this pin is an INPUT
 pinMode(LED, OUTPUT);

 Serial.begin(9600);
 Serial.println("Timer T1 test:");

 TCCR1B = 0x07;       // T1 clk = external clock source on pin T1, rising edge
 TCCR1A = 0x00;       // T1 in timer mode
  TCNT1 = 0xFFFB;     // initialize the counter (16-bit! Low+High bytes)
  TIFR1 = 0x01;       // (1<<TOV1);   if a 1 is written to a TOV1 bit
                      //              - the TOV1 bit will be cleared
} 

  /* *********************** Main Loop ************************************** */

void loop()                          // run over and over again
{ 
      if ( (TIFR1 & 0x01) == 0x01)   // If the overflow flag is set
      {
        ledState = !ledState;        // toggle the status of the ledPin
        digitalWrite(LED, ledState); // update the LED pin itself
        TCNT1 = 0xFFFB;              // Restart T1 - reload
        TIFR1 = 0x01;                // Clear the overflow flag
       }
      else
        asm("nop");                  // Do nothing

   Serial.print("Input D5 = ");
   Serial.print(digitalRead(SWITCH),BIN);
   Serial.print("  TCNT1 = ");
   Serial.print(TCNT1,DEC);
   Serial.print('\r');             // this will not work with embedded Serial Monitor,
                                 // but works fine with e.g. putty terminal
  
}