timers.c File Reference

Detailed Description

Timer Utilities implementation

Author:: Jörgen Birkler (birkler@yahoo.com)

Data Structures

struct Timer_t

Defines

#define TIMER2_REQUESTED_PRESCALER
#define TCCR2_PRESCALE
#define TIMER_RESET
#define TIMER_NO_UPDATE
#define TIMER2_ENABLE_OVERFLOW_INTERRUPT()
#define TIMER2_CLEAR_COMPARE_FLAG()
#define TIMER2_IS_COMPARE_FLAG_SET()
#define TIMER2_DISABLE_OVERFLOW_INTERRUPT()
#define TIMER2_ENABLE_ASYNCHRONOUS()
#define TIMER2_SET_COMPARE_VALUE(_val)
#define TIMER2_COUNTER()
#define TIMER2_SET_COUNTER(_val)
#define TIMER2_DISABLE_COMPARE_INTERRUPT()
#define TIMER2_ENABLE_COMPARE_INTERRUPT()
#define TIMER2_COMPARE_INTERRUPT_ENABLED()
#define TIMER2_COMPARE_INTERRUPT_DISABLED()
#define TIMER2_ASYNC_SAFETY
#define TIMER2_WAIT_ASYNC_UPDATE()
#define TCCR2_CLEAR_ON_COMP_MATCH
#define TCCR2_COM_SET_OC2
#define TCCR2_COM_TOGGLE_OC2
#define TCCR2_COM_CLEAR_OC2
#define TCCR2_COM_DISCONNECT_OC2
#define TCCR2_PRESCALE_STOPPED
#define TCCR2_PRESCALE_1
#define TCCR2_PRESCALE_8
#define TCCR2_PRESCALE_32
#define TCCR2_PRESCALE_64
#define TCCR2_PRESCALE_128
#define TCCR2_PRESCALE_256
#define TCCR2_PRESCALE_1024

Typedefs

typedef uint32_t LongMilliseconds_t

Functions

void Timers_Update (void)
Milliseconds_t Timers_DecreaseAll (const Milliseconds_t delta)
INTERRUPT (SIG_OUTPUT_COMPARE2)
INTERRUPT (SIG_OVERFLOW2)
void Timers_Init (void)
unsigned char Timers_GotoToIdle (void)
bool Timer_HasExpired (const TimerId_t TimerId)
void Timer_Reset (const TimerId_t TimerId)
void Timer_Set (const TimerId_t TimerId, const Milliseconds_t setTimeout)
void Timer_SetExpired (const TimerId_t TimerId, const Milliseconds_t setTimeout)

Variables

volatile Timer_t Timers [TIMER_LAST]

Define Documentation

#define TIMER2_REQUESTED_PRESCALER

Prescaler requested by user.
TIMER2_CLOCK_FREQ is set to the external crystal frequency in Hz, Usually 32768Hz.
TIMER2_RTC_UPDATE_TIME should be set to the time between updates to the RTC (Real Time Clock). Usually 1000 ms.
When using a crystal to clock the core the chip waits 35ms for the clock to stabilize before any code is executed. The 35ms is default but can be changed to 1ms if using a ceramic resonator by changing a fuse bit. See the application note AN1259 about the RTC clock.
Larger updates times give lower power consumption but less accurate timers. Lower values gives more accurate timers but higher power consumption.
Accuracy of the RTC is only affected by the accuracy of the crystal not by the selected TIMER2_RTC_UPDATE_TIME. The resolution of the RTC is TIMER2_RTC_UPDATE_TIME/256.
PRECISION/RESOLUTION/ACCURACY

#define TIMER_RESET

Timer is expired.

Typedef Documentation

typedef uint32_t LongMilliseconds_t

Special type used by update function.

Function Documentation

void Timers_Update ( void ) [inline, static]

Update the timers

Calculate ticks elapsed since last update
Calculate ms elapsed since last update
Update all timers and get ms until next update
Calculate ticks until next update
Enable interrupt

Milliseconds_t Timers_DecreaseAll ( const Milliseconds_t delta ) [static]

Decreases all timers with delta ms
Parameters:

delta milliseconds elapsed

Returns:
Milliseconds until next update or TIMER_NO_UPDATE if not timers are running.

INTERRUPT ( SIG_OUTPUT_COMPARE2 )

The output match compare interrupt.

INTERRUPT ( SIG_OVERFLOW2 )

Timer2 overflow interrupt.

Variable Documentation

volatile Timer_t Timers[TIMER_LAST] [static]

All the timers.