speeduino/scheduler.ino

97 lines
4.3 KiB
C++

void initialiseScheduler()
{
// Much help in this from http://arduinomega.blogspot.com.au/2011/05/timer2-and-overflow-interrupt-lets-get.html
//Schedule 1, which is uses timer 3
TCCR3B = 0x00; //Disbale Timer2 while we set it up
TCNT3 = 0; //Reset Timer Count
TIFR3 = 0x00; //Timer2 INT Flag Reg: Clear Timer Overflow Flag
TIMSK3 = 0x01; //Timer2 INT Reg: Timer2 Overflow Interrupt Enable
TCCR3A = 0x00; //Timer2 Control Reg A: Wave Gen Mode normal
TCCR3B = (1 << CS12); //Timer2 Control Reg B: Timer Prescaler set to 256. Refer to http://www.instructables.com/files/orig/F3T/TIKL/H3WSA4V7/F3TTIKLH3WSA4V7.jpg
//Schedule 2, which is uses timer 4
TCCR4B = 0x00; //Disbale Timer2 while we set it up
TCNT4 = 0; //Reset Timer Count
TIFR4 = 0x00; //Timer2 INT Flag Reg: Clear Timer Overflow Flag
TIMSK4 = 0x01; //Timer2 INT Reg: Timer2 Overflow Interrupt Enable
TCCR4A = 0x00; //Timer2 Control Reg A: Wave Gen Mode normal
TCCR4B = (1 << CS12); //Timer2 Control Reg B: Timer Prescaler set to 256. Refer to http://www.instructables.com/files/orig/F3T/TIKL/H3WSA4V7/F3TTIKLH3WSA4V7.jpg
schedule1Active = 0;
schedule2Active = 0;
}
/*
This turns schedule 1 on, gives it callback functions and resets the relevant timer based on the time in the future that this should be triggered
Args:
startCallback: The function to be called once the timeout1 is reached
timeout1: The number of uS in the future that the callback should be triggered
duration: The number of uS before endCallback is called
endCallback
*/
void setSchedule1(void (*startCallback)(), unsigned long timeout, unsigned long duration, void(*endCallback)())
{
//We need to calculate the value to reset the timer to (preload) in order to achieve the desired overflow time
//As the timer is ticking every 16uS (Time per Tick = (Prescale)*(1/Frequency))
//TODO: Need to add check for timeout > 1048576 ????
TCNT3 = 65536 - (timeout / 16); //Each tick occurs every 16uS with a 256 prescaler so divide the timeout by 16 to get ther required number of ticks. Subtract this from the total number of tick (65536 for 16-bit timer)
schedule1Duration = duration;
schedule1StartCallback = startCallback; //Name the start callback function
schedule1EndCallback = endCallback; //Name the start callback function
schedule1Active = 1; //Turn this schedule on and set it
}
//As above, but for schedule2
void setSchedule2(void (*startCallback)(), unsigned long timeout, unsigned long duration, void(*endCallback)())
{
//TODO: Need to add check for timeout > 1048576 ????
TCNT4 = 65536 - (timeout / 16); //Each tick occurs every 16uS with a 256 prescaler so divide the timeout by 16 to get ther required number of ticks. Subtract this from the total number of tick (65536 for 16-bit timer)
schedule2Duration = duration;
schedule2StartCallback = startCallback; //Name the callback function
schedule2EndCallback = endCallback; //Name the callback function
schedule2Active = 1; //Turn this schedule on
}
//Timer3 (schedule 1) Overflow Interrupt Vector
//This needs to call the callback function if one has been provided and rest the timer
ISR(TIMER3_OVF_vect)
{
if (schedule1Active == 1) //Check to see if this schedule is turn on
{
schedule1StartCallback(); //Replace with user provided callback
schedule1Active = 2; //Turn off the callback
TCNT3 = 65536 - (schedule1Duration / 16);
}
else if (schedule1Active == 2)
{
schedule1EndCallback();
schedule1Active = 0; //Turn off the callback
TCNT3 = 0; //Reset Timer to 0 out of 255
}
TIFR3 = 0x00; //Timer2 INT Flag Reg: Clear Timer Overflow Flag
}
//AS above for schedule2
ISR(TIMER4_OVF_vect)
{
if (schedule2Active == 1) //A value of 1 means call the start callback
{
schedule2StartCallback();
schedule2Active = 2; //Set to call the end callback on the next run
TCNT4 = 65536 - (schedule2Duration / 16);
}
else if (schedule2Active == 2)
{
schedule2EndCallback();
schedule2Active = 0; //Turn off the callback
TCNT4 = 0; //Reset Timer to 0 out of 255
}
TIFR4 = 0x00; //Timer2 INT Flag Reg: Clear Timer Overflow Flag
}