* Project: Timer_0_Polling_Experiment
* Author: Peter Brook tidied by Jane-Maree Howard on..
* Date: ..Wednesday 26/10/2011
* Platform: Arduino 22
* Purpose: To visually demonstrate Timer0 polling
* Operation: Polls Timer0 prescaled by 1024; toggles LED on/off every second
* Declare: toggle variable; counter vble; ToggleLED() routine
* Setup(): Serial port @9600baud; Prints opening statement; delays 5 seconds
* set TImerMaSK0 to zero - turn of Timer0 interrupt;
* set Timer/CounterControlRegister0B to DEC5; prescaler /s by 1024;
* Loop(): idle until TimerInterruptFlagRegister0 == 1;
* reset TIFR0; count 1 'tick'(from 0 to 60, 61 'ticks');
* @ 60'ticks', reset 'ticks' & toggle LED on/off
*/
int state = 1; // LED toggle vble - init. OFF!
byte ticks = 0; // counts up towards 60, the LED toggle value
void setup()
{
Serial.begin(9600); // Serial port @ 9600 baud
Serial.println("\n\tInitial state is OFF\n\t");
delay(5000); // wait 5 seconds
// initialize digital pin 13 as an output.
// Pin 13 has an LED connected on most Arduino boards:
pinMode(13, OUTPUT);
//after this, can't use 'delay() any more
TIMSK0 = 0; // turn off Interrupt for Timer0
TCCR0B = 5; // Prescaler divides by 1024; BIN101 = DEC5
}//setup()
void loop()
{
while(byte(TIFR0 &0x01) ==0) // loop till flag goes up
{/* do nothing */}
TIFR0 = 1; // clear flag
ticks++; // count a tick
if (ticks == 60) // preset value
{
ticks=0; // reset 'ticks'
Serial.print("\tTT ");
ToggleLED(); // toggle LED
}//if()
}// loop()
void ToggleLED()
{
if (state==1)
{
digitalWrite(13,LOW); // LED turns OFF
state = 0; // toggle 'state' vble
Serial.print("I've toggled OFF"); // Serial Monitor o/p
}//if()
else
{
digitalWrite(13,HIGH); // LED turns ON
state=1; // toggle 'state' vble
Serial.println("I've toggled ON "); // Serial Monitor o/p
}//else()
}//ToggleLED()
In the code, the initial state of the on-board LED (pin 13) is OFF.
The SM output records the first toggle ("TT") & the LED
(of course ) stays OFF.
From then on, the LED's recorded toggled state matches that of the on-board LED (pin 13)
