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FlexiTimer2.cpp
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FlexiTimer2.cpp
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/*
FlexiTimer2.h - Using timer2 with a configurable resolution
Wim Leers <work@wimleers.com>
Based on MsTimer2
Javier Valencia <javiervalencia80@gmail.com>
History:
16/Dec/2011 - Added Teensy/Teensy++ support (bperrybap)
note: teensy uses timer4 instead of timer2
25/April/10 - Based on MsTimer2 V0.5 (from 29/May/09)
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <FlexiTimer2.h>
unsigned long FlexiTimer2::time_units;
void (*FlexiTimer2::func)();
volatile unsigned long FlexiTimer2::count;
volatile char FlexiTimer2::overflowing;
volatile unsigned int FlexiTimer2::tcnt2;
void FlexiTimer2::set(unsigned long ms, void (*f)()) {
FlexiTimer2::set(ms, 0.001, f);
}
/**
* @param resolution
* 0.001 implies a 1 ms (1/1000s = 0.001s = 1ms) resolution. Therefore,
* 0.0005 implies a 0.5 ms (1/2000s) resolution. And so on.
*/
void FlexiTimer2::set(unsigned long units, double resolution, void (*f)()) {
float prescaler = 0.0;
if (units == 0)
time_units = 1;
else
time_units = units;
func = f;
#if defined (__AVR_ATmega168__) || defined (__AVR_ATmega48__) || defined (__AVR_ATmega88__) || defined (__AVR_ATmega328P__) || defined (__AVR_ATmega1280__) || defined (__AVR_ATmega2560__) || defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB1286__)
TIMSK2 &= ~(1<<TOIE2);
TCCR2A &= ~((1<<WGM21) | (1<<WGM20));
TCCR2B &= ~(1<<WGM22);
ASSR &= ~(1<<AS2);
TIMSK2 &= ~(1<<OCIE2A);
if ((F_CPU >= 1000000UL) && (F_CPU <= 16000000UL)) { // prescaler set to 64
TCCR2B |= (1<<CS22);
TCCR2B &= ~((1<<CS21) | (1<<CS20));
prescaler = 64.0;
} else if (F_CPU < 1000000UL) { // prescaler set to 8
TCCR2B |= (1<<CS21);
TCCR2B &= ~((1<<CS22) | (1<<CS20));
prescaler = 8.0;
} else { // F_CPU > 16Mhz, prescaler set to 128
TCCR2B |= ((1<<CS22) | (1<<CS20));
TCCR2B &= ~(1<<CS21);
prescaler = 128.0;
}
#elif defined (__AVR_ATmega8__)
TIMSK &= ~(1<<TOIE2);
TCCR2 &= ~((1<<WGM21) | (1<<WGM20));
TIMSK &= ~(1<<OCIE2);
ASSR &= ~(1<<AS2);
if ((F_CPU >= 1000000UL) && (F_CPU <= 16000000UL)) { // prescaler set to 64
TCCR2 |= (1<<CS22);
TCCR2 &= ~((1<<CS21) | (1<<CS20));
prescaler = 64.0;
} else if (F_CPU < 1000000UL) { // prescaler set to 8
TCCR2 |= (1<<CS21);
TCCR2 &= ~((1<<CS22) | (1<<CS20));
prescaler = 8.0;
} else { // F_CPU > 16Mhz, prescaler set to 128
TCCR2 |= ((1<<CS22) && (1<<CS20));
TCCR2 &= ~(1<<CS21);
prescaler = 128.0;
}
#elif defined (__AVR_ATmega128__)
TIMSK &= ~(1<<TOIE2);
TCCR2 &= ~((1<<WGM21) | (1<<WGM20));
TIMSK &= ~(1<<OCIE2);
if ((F_CPU >= 1000000UL) && (F_CPU <= 16000000UL)) { // prescaler set to 64
TCCR2 |= ((1<<CS21) | (1<<CS20));
TCCR2 &= ~(1<<CS22);
prescaler = 64.0;
} else if (F_CPU < 1000000UL) { // prescaler set to 8
TCCR2 |= (1<<CS21);
TCCR2 &= ~((1<<CS22) | (1<<CS20));
prescaler = 8.0;
} else { // F_CPU > 16Mhz, prescaler set to 256
TCCR2 |= (1<<CS22);
TCCR2 &= ~((1<<CS21) | (1<<CS20));
prescaler = 256.0;
}
#elif defined (__AVR_ATmega32U4__)
TCCR4B = 0;
TCCR4A = 0;
TCCR4C = 0;
TCCR4D = 0;
TCCR4E = 0;
if (F_CPU >= 16000000L) {
TCCR4B = (1<<CS43) | (1<<PSR4);
prescaler = 128.0;
} else if (F_CPU >= 8000000L) {
TCCR4B = (1<<CS42) | (1<<CS41) | (1<<CS40) | (1<<PSR4);
prescaler = 64.0;
} else if (F_CPU >= 4000000L) {
TCCR4B = (1<<CS42) | (1<<CS41) | (1<<PSR4);
prescaler = 32.0;
} else if (F_CPU >= 2000000L) {
TCCR4B = (1<<CS42) | (1<<CS40) | (1<<PSR4);
prescaler = 16.0;
} else if (F_CPU >= 1000000L) {
TCCR4B = (1<<CS42) | (1<<PSR4);
prescaler = 8.0;
} else if (F_CPU >= 500000L) {
TCCR4B = (1<<CS41) | (1<<CS40) | (1<<PSR4);
prescaler = 4.0;
} else {
TCCR4B = (1<<CS41) | (1<<PSR4);
prescaler = 2.0;
}
tcnt2 = (int)((float)F_CPU * resolution / prescaler) - 1;
OCR4C = tcnt2;
return;
#else
#error Unsupported CPU type
#endif
tcnt2 = 256 - (int)((float)F_CPU * resolution / prescaler);
}
void FlexiTimer2::setFunc(void (*f)())
{
func = f;
}
void FlexiTimer2::start() {
count = 0;
overflowing = 0;
#if defined (__AVR_ATmega168__) || defined (__AVR_ATmega48__) || defined (__AVR_ATmega88__) || defined (__AVR_ATmega328P__) || defined (__AVR_ATmega1280__) || defined(__AVR_ATmega2560__) || defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB1286__)
TCNT2 = tcnt2;
TIMSK2 |= (1<<TOIE2);
#elif defined (__AVR_ATmega128__)
TCNT2 = tcnt2;
TIMSK |= (1<<TOIE2);
#elif defined (__AVR_ATmega8__)
TCNT2 = tcnt2;
TIMSK |= (1<<TOIE2);
#elif defined (__AVR_ATmega32U4__)
TIFR4 = (1<<TOV4);
TCNT4 = 0;
TIMSK4 = (1<<TOIE4);
#endif
}
void FlexiTimer2::stop() {
#if defined (__AVR_ATmega168__) || defined (__AVR_ATmega48__) || defined (__AVR_ATmega88__) || defined (__AVR_ATmega328P__) || defined (__AVR_ATmega1280__) || defined(__AVR_ATmega2560__) || defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB1286__)
TIMSK2 &= ~(1<<TOIE2);
#elif defined (__AVR_ATmega128__)
TIMSK &= ~(1<<TOIE2);
#elif defined (__AVR_ATmega8__)
TIMSK &= ~(1<<TOIE2);
#elif defined (__AVR_ATmega32U4__)
TIMSK4 = 0;
#endif
}
void FlexiTimer2::_overflow() {
count += 1;
if (count >= time_units && !overflowing) {
overflowing = 1;
count = count - time_units; // subtract time_uints to catch missed overflows
// set to 0 if you don't want this.
(*func)();
overflowing = 0;
}
}
#if defined (__AVR_ATmega32U4__)
ISR(TIMER4_OVF_vect) {
#else
ISR(TIMER2_OVF_vect) {
#endif
#if defined (__AVR_ATmega168__) || defined (__AVR_ATmega48__) || defined (__AVR_ATmega88__) || defined (__AVR_ATmega328P__) || defined (__AVR_ATmega1280__) || defined(__AVR_ATmega2560__) || defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB1286__)
TCNT2 = FlexiTimer2::tcnt2;
#elif defined (__AVR_ATmega128__)
TCNT2 = FlexiTimer2::tcnt2;
#elif defined (__AVR_ATmega8__)
TCNT2 = FlexiTimer2::tcnt2;
#elif defined (__AVR_ATmega32U4__)
// not necessary on 32u4's high speed timer4
#endif
FlexiTimer2::_overflow();
}