speeduino/scheduler.h

/*
This scheduler is designed to maintain 2 schedules for use by the fuel and ignition systems. 
It functions by waiting for the overflow vectors from each of the timers in use to overflow, which triggers an interrupt

//Technical
Currently I am prescaling the 16-bit timers to 256 for injection and 64 for ignition. This means that the counter increments every 16us (injection) / 4uS (ignition) and will overflow every 1048576uS
Max Period = (Prescale)*(1/Frequency)*(2^17)
(See http://playground.arduino.cc/code/timer1)
This means that the precision of the scheduler is 16uS (+/- 8uS of target) for fuel and 4uS (+/- 2uS) for ignition

/Features
This differs from most other schedulers in that its calls are non-recurring (IE You schedule an event at a certain time and once it has occurred, it will not reoccur unless you explicitely ask for it)
Each timer can have only 1 callback associated with it at any given time. If you call the setCallback function a 2nd time, the original schedule will be overwritten and not occur

Timer identification
The Arduino timer3 is used for schedule 1
The Arduino timer4 is used for schedule 2
Both of these are 16-bit timers (ie count to 65536)
See page 136 of the processors datasheet: http://www.atmel.com/Images/doc2549.pdf

256 prescale gives tick every 16uS
256 prescale gives overflow every 1048576uS (This means maximum wait time is 1.0485 seconds)

*/
#ifndef SCHEDULER_H
#define SCHEDULER_H

#ifdef __SAM3X8E__
 //Do stuff for ARM based CPUs 
#else
  #include <avr/interrupt.h> 
  #include <avr/io.h>
#endif

void initialiseSchedulers();
void setFuelSchedule1(void (*startCallback)(), unsigned long timeout, unsigned long duration, void(*endCallback)());
void setFuelSchedule2(void (*startCallback)(), unsigned long timeout, unsigned long duration, void(*endCallback)());
void setFuelSchedule3(void (*startCallback)(), unsigned long timeout, unsigned long duration, void(*endCallback)());
void setFuelSchedule4(void (*startCallback)(), unsigned long timeout, unsigned long duration, void(*endCallback)());
void setIgnitionSchedule1(void (*startCallback)(), unsigned long timeout, unsigned long duration, void(*endCallback)());
void setIgnitionSchedule2(void (*startCallback)(), unsigned long timeout, unsigned long duration, void(*endCallback)());
void setIgnitionSchedule3(void (*startCallback)(), unsigned long timeout, unsigned long duration, void(*endCallback)());
void setIgnitionSchedule4(void (*startCallback)(), unsigned long timeout, unsigned long duration, void(*endCallback)());

enum ScheduleStatus {OFF, PENDING, RUNNING}; //The 3 statuses that a schedule can have

struct Schedule {
  volatile unsigned long duration;
  volatile ScheduleStatus Status;
  void (*StartCallback)(); //Start Callback function for schedule
  void (*EndCallback)(); //Start Callback function for schedule
  volatile unsigned long startTime;
};

Schedule fuelSchedule1;
Schedule fuelSchedule2;
Schedule fuelSchedule3;
Schedule fuelSchedule4;
Schedule ignitionSchedule1;
Schedule ignitionSchedule2;
Schedule ignitionSchedule3;
Schedule ignitionSchedule4;

#endif // SCHEDULER_H