TimerOne库文件

/* * Interrupt and PWM utilities for 16 bit Timer1 on ATmega168/328 * Original code by Jesse Tane for http://labs.ideo.com August 2008 * Modified March 2009 by Jérôme Despatis and Jesse Tane for ATmega328 support * Modified June 2009 by Michael Polli and Jesse Tane to fix a bug in setPeriod() which caused the timer to stop * * This is free software. You can redistribute it and/or modify it under * the terms of Creative Commons Attribution 3.0 United States License. * To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/us/ * or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA. * */ #include "TimerOne.h" TimerOne Timer1; // preinstatiate ISR(TIMER1_OVF_vect) // interrupt service routine that wraps a user defined function supplied by attachInterrupt { Timer1.isrCallback(); } void TimerOne::initialize(long microseconds) { TCCR1A = 0; // clear control register A TCCR1B = _BV(WGM13); // set mode as phase and frequency correct pwm, stop the timer setPeriod(microseconds); } void TimerOne::setPeriod(long microseconds) { long cycles = (F_CPU * microseconds) / 2000000; // the counter runs backwards after TOP, interrupt is at BOTTOM so divide microseconds by 2 if(cycles < RESOLUTION) clockSelectBits = _BV(CS10); // no prescale, full xtal else if((cycles >>= 3) < RESOLUTION) clockSelectBits = _BV(CS11); // prescale by /8 else if((cycles >>= 3) < RESOLUTION) clockSelectBits = _BV(CS11) | _BV(CS10); // prescale by /64 else if((cycles >>= 2) < RESOLUTION) clockSelectBits = _BV(CS12); // prescale by /256 else if((cycles >>= 2) < RESOLUTION) clockSelectBits = _BV(CS12) | _BV(CS10); // prescale by /1024 else cycles = RESOLUTION - 1, clockSelectBits = _BV(CS12) | _BV(CS10); // request was out of bounds, set as maximum ICR1 = pwmPeriod = cycles; // ICR1 is TOP in p & f correct pwm mode TCCR1B &= ~(_BV(CS10) | _BV(CS11) | _BV(CS12)); TCCR1B |= clockSelectBits; // reset clock select register } void TimerOne::setPwmDuty(char pin, int duty) { unsigned long dutyCycle = pwmPeriod; dutyCycle *= duty; dutyCycle >>= 10; if(pin == 1 || pin == 9) OCR1A = dutyCycle; else if(pin == 2 || pin == 10) OCR1B = dutyCycle; } void TimerOne::pwm(char pin, int duty, long microseconds) // expects duty cycle to be 10 bit (1024) { if(microseconds > 0) setPeriod(microseconds); if(pin == 1 || pin == 9) { DDRB |= _BV(PORTB1); // sets data direction register for pwm output pin TCCR1A |= _BV(COM1A1); // activates the output pin } else if(pin == 2 || pin == 10) { DDRB |= _BV(PORTB2); TCCR1A |= _BV(COM1B1); } setPwmDuty(pin, duty); start(); } void TimerOne::disablePwm(char pin) { if(pin == 1 || pin == 9) TCCR1A &= ~_BV(COM1A1); // clear the bit that enables pwm on PB1 else if(pin == 2 || pin == 10) TCCR1A &= ~_BV(COM1B1); // clear the bit that enables pwm on PB2 } void TimerOne::attachInterrupt(void (*isr)(), long microseconds) { if(microseconds > 0) setPeriod(microseconds); isrCallback = isr; // register the user's callback with the real ISR TIMSK1 = _BV(TOIE1); // sets the timer overflow interrupt enable bit sei(); // ensures that interrupts are globally enabled start(); } void TimerOne::detachInterrupt() { TIMSK1 &= ~_BV(TOIE1); // clears the timer overflow interrupt enable bit } void TimerOne::start() { TCCR1B |= clockSelectBits; } void TimerOne::stop() { TCCR1B &= ~(_BV(CS10) | _BV(CS11) | _BV(CS12)); // clears all clock selects bits } void TimerOne::restart() { TCNT1 = 0; }