timers.h

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/*
NOTE - This file and it's associated functions need a CLEARER NAME
 
//Purpose
We're implementing a lower frequency interrupt loop to perform calculations that are needed less often, some of which depend on time having passed (delta/time) to be meaningful.
 
 
//Technical
Timer2 is only 8bit so we are setting the prescaler to 128 to get the most out of it. This means that the counter increments every 0.008ms and the overflow at 256 will be after 2.048ms
Max Period = (Prescale)*(1/Frequency)*(2^8)
(See arduinomega.blogspot.com.au/2011/05/timer2-and-overflow-interrupt-lets-get.html)
 
We're after a 1ms interval so we'll need 131 intervals to reach this ( 1ms / 0.008ms per tick = 125).
Hence we will preload the timer with 131 cycles to leave 125 until overflow (1ms).
 
*/
#ifndef TIMERS_H
#define TIMERS_H
 
#include "globals.h"
 
#define SET_COMPARE(compare, value) compare = (COMPARE_TYPE)(value) // It is important that we cast this to the actual overflow limit of the timer. The compare variables type can be bigger than the timer overflow.
 
#if(defined(CORE_TEENSY) || defined(CORE_STM32))
  #define TACHO_PULSE_LOW()         (digitalWrite(pinTachOut, LOW))
  #define TACHO_PULSE_HIGH()        (digitalWrite(pinTachOut, HIGH))
#else
  #define TACHO_PULSE_HIGH()        (*tach_pin_port |= (tach_pin_mask))
  #define TACHO_PULSE_LOW()         (*tach_pin_port &= ~(tach_pin_mask))
#endif
enum TachoOutputStatus {TACHO_INACTIVE, READY, ACTIVE}; //The 3 statuses that the tacho output pulse can have. NOTE: Cannot just use 'INACTIVE' as this is already defined within the Teensy Libs
 
extern volatile TachoOutputStatus tachoOutputFlag;
extern volatile uint16_t tachoSweepIncr;
 
#define TACHO_SWEEP_TIME_MS 1500
#define TACHO_SWEEP_RAMP_MS (TACHO_SWEEP_TIME_MS * 2 / 3)
#define MS_PER_SEC  1000
 
extern volatile unsigned int dwellLimit_uS;
 
#if defined (CORE_TEENSY)
  extern IntervalTimer lowResTimer;
#endif
void oneMSInterval(void);
void initialiseTimers(void);
 
#endif // TIMERS_H