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timer.c
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timer.c
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/*! \file timer.c \brief System Timer function library. */
//*****************************************************************************
//
// File Name : 'timer.c'
// Title : System Timer function library
// Author : Pascal Stang - Copyright (C) 2000-2002
// Created : 11/22/2000
// Revised : 07/09/2003
// Version : 1.1
// Target MCU : Atmel AVR Series
// Editor Tabs : 4
//
// This code is distributed under the GNU Public License
// which can be found at http://www.gnu.org/licenses/gpl.txt
//
//*****************************************************************************
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <avr/sleep.h>
#include "global.h"
#include "timer.h"
//#include "rprintf.h"
// Program ROM constants
// the prescale division values stored in order of timer control register index
// STOP, CLK, CLK/8, CLK/64, CLK/256, CLK/1024
unsigned short __attribute__ ((progmem)) TimerPrescaleFactor[] = {0,1,8,64,256,1024};
// the prescale division values stored in order of timer control register index
// STOP, CLK, CLK/8, CLK/32, CLK/64, CLK/128, CLK/256, CLK/1024
unsigned short __attribute__ ((progmem)) TimerRTCPrescaleFactor[] = {0,1,8,32,64,128,256,1024};
// Global variables
// time registers
volatile unsigned long TimerPauseReg;
volatile unsigned long Timer0Reg0;
volatile unsigned long Timer2Reg0;
typedef void (*voidFuncPtr)(void);
volatile static voidFuncPtr TimerIntFunc[TIMER_NUM_INTERRUPTS];
// delay for a minimum of <us> microseconds
// the time resolution is dependent on the time the loop takes
// e.g. with 4Mhz and 5 cycles per loop, the resolution is 1.25 us
#if 0
void delay_us(unsigned short time_us)
{
unsigned short delay_loops;
register unsigned short i;
delay_loops = (time_us+3)/5*CYCLES_PER_US; // +3 for rounding up (dirty)
// one loop takes 5 cpu cycles
for (i=0; i < delay_loops; i++) {};
}
void delay_ms(unsigned char time_ms)
{
unsigned short delay_count = F_CPU / 4000;
unsigned short cnt;
asm volatile ("\n"
"L_dl1%=:\n\t"
"mov %A0, %A2\n\t"
"mov %B0, %B2\n"
"L_dl2%=:\n\t"
"sbiw %A0, 1\n\t"
"brne L_dl2%=\n\t"
"dec %1\n\t" "brne L_dl1%=\n\t":"=&w" (cnt)
:"r"(time_ms), "r"((unsigned short) (delay_count))
);
}
#endif
#if 1
void timer0SetPrescaler(u08 prescale)
{
// set prescaler on timer 0
outb(TCCR0, (inb(TCCR0) & ~TIMER_PRESCALE_MASK) | prescale);
}
void timerInit(void)
{
u08 intNum;
// detach all user functions from interrupts
for(intNum=0; intNum<TIMER_NUM_INTERRUPTS; intNum++)
timerDetach(intNum);
// initialize all timers
timer0Init();
timer1Init();
// enable interrupts
sei();
}
void timer0Init()
{
// initialize timer 0
timer0SetPrescaler( TIMER0PRESCALE ); // set prescaler
outb(TCNT0, 0); // reset TCNT0
sbi(TIMSK0, TOIE0); // enable TCNT0 overflow interrupt
timer0ClearOverflowCount(); // initialize time registers
}
u16 timer0GetPrescaler(void)
{
// get the current prescaler setting
return (pgm_read_word(TimerPrescaleFactor+(inb(TCCR0) & TIMER_PRESCALE_MASK)));
}
#endif
void timer1Init(void)
{
// initialize timer 1
timer1SetPrescaler( TIMER1PRESCALE ); // set prescaler
outb(TCNT1H, 0); // reset TCNT1
outb(TCNT1L, 0);
sbi(TIMSK1, TOIE1); // enable TCNT1 overflow
}
void timer1SetPrescaler(u08 prescale)
{
// set prescaler on timer 1
outb(TCCR1B, (inb(TCCR1B) & ~TIMER_PRESCALE_MASK) | prescale);
}
u16 timer1GetPrescaler(void)
{
// get the current prescaler setting
return (pgm_read_word(TimerPrescaleFactor+(inb(TCCR1B) & TIMER_PRESCALE_MASK)));
}
#if 1
void timerAttach(u08 interruptNum, void (*userFunc)(void) )
{
// make sure the interrupt number is within bounds
if(interruptNum < TIMER_NUM_INTERRUPTS)
{
// set the interrupt function to run
// the supplied user's function
TimerIntFunc[interruptNum] = userFunc;
}
}
void timerDetach(u08 interruptNum)
{
// make sure the interrupt number is within bounds
if(interruptNum < TIMER_NUM_INTERRUPTS)
{
// set the interrupt function to run nothing
TimerIntFunc[interruptNum] = 0;
}
}
#endif
u32 timerMsToTics(u16 ms)
{
// calculate the prescaler division rate
u16 prescaleDiv = 1<<(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));
// calculate the number of timer tics in x milliseconds
return (ms*(F_CPU/(prescaleDiv*256)))/1000;
}
u16 timerTicsToMs(u32 tics)
{
// calculate the prescaler division rate
//u16 prescaleDiv = 1<<(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));
u16 prescaleDiv = 1<<(pgm_read_byte(TimerPrescaleFactor+inb(TCCR1B)));
// calculate the number of milliseconds in x timer tics
return (tics*1000*(prescaleDiv*256))/F_CPU;
}
#if 0
void timerPause(unsigned short pause_ms)
{
// pauses for exactly <pause_ms> number of milliseconds
u08 timerThres;
u32 ticRateHz;
u32 pause;
// capture current pause timer value
timerThres = inb(TCNT0);
// reset pause timer overflow count
TimerPauseReg = 0;
// calculate delay for [pause_ms] milliseconds
// prescaler division = 1<<(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)))
ticRateHz = F_CPU/timer0GetPrescaler();
// precision management
// prevent overflow and precision underflow
// -could add more conditions to improve accuracy
if( ((ticRateHz < 429497) && (pause_ms <= 10000)) )
pause = (pause_ms*ticRateHz)/1000;
else
pause = pause_ms*(ticRateHz/1000);
// loop until time expires
while( ((TimerPauseReg<<8) | inb(TCNT0)) < (pause+timerThres) )
{
if( TimerPauseReg < (pause>>8));
{
// save power by idling the processor
set_sleep_mode(SLEEP_MODE_IDLE);
sleep_mode();
}
}
/* old inaccurate code, for reference
// calculate delay for [pause_ms] milliseconds
u16 prescaleDiv = 1<<(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));
u32 pause = (pause_ms*(F_CPU/(prescaleDiv*256)))/1000;
TimerPauseReg = 0;
while(TimerPauseReg < pause);
*/
}
#endif
void timer0ClearOverflowCount(void)
{
// clear the timer overflow counter registers
Timer0Reg0 = 0; // initialize time registers
}
long timer0GetOverflowCount(void)
{
// return the current timer overflow count
// (this is since the last timer0ClearOverflowCount() command was called)
return Timer0Reg0;
}
//! Interrupt handler for tcnt0 overflow interrupt
ISR(TIMER0_OVF_vect)
{
Timer0Reg0++; // increment low-order counter
// increment pause counter
TimerPauseReg++;
// if a user function is defined, execute it too
if(TimerIntFunc[TIMER0OVERFLOW_INT])
TimerIntFunc[TIMER0OVERFLOW_INT]();
}
//! Interrupt handler for tcnt1 overflow interrupt
ISR(TIMER1_OVF_vect)
{
// if a user function is defined, execute it
if(TimerIntFunc[TIMER1OVERFLOW_INT])
TimerIntFunc[TIMER1OVERFLOW_INT]();
}
#if 0
#ifdef OCR0
// include support for Output Compare 0 for new AVR processors that support it
//! Interrupt handler for OutputCompare0 match (OC0) interrupt
ISR(TIMER0_COMP_vect)
{
// if a user function is defined, execute it
if(TimerIntFunc[TIMER0OUTCOMPARE_INT])
TimerIntFunc[TIMER0OUTCOMPARE_INT]();
}
#endif
//! Interrupt handler for CutputCompare1A match (OC1A) interrupt
ISR(TIMER1_COMPA_vect)
{
// if a user function is defined, execute it
if(TimerIntFunc[TIMER1OUTCOMPAREA_INT])
TimerIntFunc[TIMER1OUTCOMPAREA_INT]();
}
//! Interrupt handler for OutputCompare1B match (OC1B) interrupt
ISR(TIMER1_COMPB_vect)
{
// if a user function is defined, execute it
if(TimerIntFunc[TIMER1OUTCOMPAREB_INT])
TimerIntFunc[TIMER1OUTCOMPAREB_INT]();
}
//! Interrupt handler for InputCapture1 (IC1) interrupt
ISR(TIMER1_CAPT_vect)
{
// if a user function is defined, execute it
if(TimerIntFunc[TIMER1INPUTCAPTURE_INT])
TimerIntFunc[TIMER1INPUTCAPTURE_INT]();
}
#endif