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 * Timebase software module. Utilizes timer0 to provide a 32bit timebase with
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 * Timebase software module. Utilizes timer0 to provide a 32bit timebase with
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 * millisecond-granularity to the application.
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 * millisecond-granularity to the application.
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 *
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 * @target  ATmega8
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 *
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 *
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 * @author  Martin Thomas
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 * @author  Martin Thomas
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 * @author  Jimmy Myhrman
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 * @author  Jimmy Myhrman
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 *
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 *
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 * @date    2006-11-19
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 * @date    2006-11-19
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 */
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 */
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/*-----------------------------------------------------------------------------
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/*-----------------------------------------------------------------------------
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 * Includes
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 * Includes
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 *---------------------------------------------------------------------------*/
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 *---------------------------------------------------------------------------*/
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#include <inttypes.h>
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#include <inttypes.h>
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#include <avr/io.h>
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include <avr/interrupt.h>
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#include <timebase.h>
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#include <timebase.h>
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/*-----------------------------------------------------------------------------
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/*-----------------------------------------------------------------------------
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 * Globals
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 * Globals
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 *---------------------------------------------------------------------------*/
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 *---------------------------------------------------------------------------*/
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volatile uint32_t gMilliSecTick;
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volatile uint32_t gMilliSecTick;
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/*-----------------------------------------------------------------------------
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/*-----------------------------------------------------------------------------
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 * Interrupt Service Routines
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 * Interrupt Service Routines
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 *---------------------------------------------------------------------------*/
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 *---------------------------------------------------------------------------*/
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ISR(SIG_OVERFLOW0) {
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ISR(SIG_OVERFLOW0) {
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    TCNT0 = TIMEBASE_RELOAD;
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    TCNT0 = TIMEBASE_RELOAD;
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    gMilliSecTick++;
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    gMilliSecTick++;
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}
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}
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/*-----------------------------------------------------------------------------
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/*-----------------------------------------------------------------------------
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 * Public Functions
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 * Public Functions
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 *---------------------------------------------------------------------------*/
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 *---------------------------------------------------------------------------*/
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/**
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/**
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 * Initializes the timebase. The hardware timer interrupt source will be
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 * Initializes the timebase. The hardware timer interrupt source will be
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 * enabled, but global interrupts need to be enabled by the application.
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 * enabled, but global interrupts need to be enabled by the application.
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 */
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 */
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void Timebase_Init() {
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void Timebase_Init() {
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    #if defined(__AVR_ATmega8__)
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    TCCR0 = (1<<CS01) | (1<<CS00); // prescaler: 64
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    TCCR0 = (1<<CS01) | (1<<CS00); // prescaler: 64
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    TCNT0 = TIMEBASE_RELOAD; // set initial reload-value
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    TCNT0 = TIMEBASE_RELOAD; // set initial reload-value
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    TIFR  |= (1<<TOV0);  // clear overflow int.
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    TIFR  |= (1<<TOV0);  // clear overflow int.
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    TIMSK |= (1<<TOIE0); // enable overflow-interrupt
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    TIMSK |= (1<<TOIE0); // enable overflow-interrupt
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    #endif
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    #if defined(__AVR_ATmega88__)
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    TCCR0A = (1<<CS01) | (1<<CS00); // prescaler: 64
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    TCNT0 = TIMEBASE_RELOAD; // set initial reload-value
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    TIFR0  |= (1<<TOV0);  // clear overflow int.
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    TIMSK0 |= (1<<TOIE0); // enable overflow-interrupt
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    #endif
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}
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}
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/**
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/**
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 * Reads the current time.
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 * Reads the current time.
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 *
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 *
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 * @return
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 * @return
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 *      The current time in milliseconds (32bit value).
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 *      The current time in milliseconds (32bit value).
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    cli();
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    cli();
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    res = gMilliSecTick;
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    res = gMilliSecTick;
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    SREG=sreg;
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    SREG=sreg;
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    return res;
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    return res;
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}
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}
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/**
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/**
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 * Checks how much time has passed since a given timestamp.
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 * Checks how much time has passed since a given timestamp.
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 *
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 *
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 * @param t0
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 * @param t0