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#include <Servo.h>
#include <avr/interrupt.h>
/*
Servo.h - Hardware Servo Timer Library
Author: Jim Studt, jim@federated.com
Copyright (c) 2007 David A. Mellis. All right reserved.
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
*/
uint8_t Servo::attached9 = 0;
uint8_t Servo::attached10 = 0;
void Servo::seizeTimer1()
{
uint8_t oldSREG = SREG;
cli();
TCCR1A = _BV(WGM11); /* Fast PWM, ICR1 is top */
TCCR1B = _BV(WGM13) | _BV(WGM12) /* Fast PWM, ICR1 is top */
| _BV(CS11) /* div 8 clock prescaler */
;
OCR1A = 3000;
OCR1B = 3000;
ICR1 = clockCyclesPerMicrosecond()*(20000L/8); // 20000 uS is a bit fast for the refresh, 20ms, but
// it keeps us from overflowing ICR1 at 20MHz clocks
// That "/8" at the end is the prescaler.
#if defined(__AVR_ATmega168__)
TIMSK1 &= ~(_BV(OCIE1A) | _BV(OCIE1B) | _BV(TOIE1) );
#else
TIMSK &= ~(_BV(TICIE1) | _BV(OCIE1A) | _BV(OCIE1B) | _BV(TOIE1) );
#endif
SREG = oldSREG; // undo cli()
}
void Servo::releaseTimer1() {}
#define NO_ANGLE (0xff)
Servo::Servo() : pin(0), angle(NO_ANGLE), min16(34), max16(150) {}
Servo::Servo(int min, int max) : pin(0), angle(NO_ANGLE), min16(min / 16), max16(max / 16) {}
uint8_t Servo::attach(int pinArg)
{
if (pinArg != 9 && pinArg != 10) return 0;
pin = pinArg;
angle = NO_ANGLE;
digitalWrite(pin, LOW);
pinMode(pin, OUTPUT);
if (!attached9 && !attached10) seizeTimer1();
if (pin == 9) {
attached9 = 1;
TCCR1A = TCCR1A & ~_BV(COM1A0) | _BV(COM1A1);
}
if (pin == 10) {
attached10 = 1;
TCCR1A = TCCR1A & ~_BV(COM1B0) | _BV(COM1B1);
}
return 1;
}
void Servo::detach()
{
// muck with timer flags
if (pin == 9) {
attached9 = 0;
TCCR1A = TCCR1A & ~_BV(COM1A0) & ~_BV(COM1A1);
pinMode(pin, INPUT);
}
if (pin == 10) {
attached10 = 0;
TCCR1A = TCCR1A & ~_BV(COM1B0) & ~_BV(COM1B1);
pinMode(pin, INPUT);
}
if (!attached9 && !attached10) releaseTimer1();
}
void Servo::write(int angleArg)
{
uint16_t p;
if (angleArg < 0) angleArg = 0;
if (angleArg > 180) angleArg = 180;
angle = angleArg;
// bleh, have to use longs to prevent overflow, could be tricky if always a 16MHz clock, but not true
// That 8L on the end is the TCNT1 prescaler, it will need to change if the clock's prescaler changes,
// but then there will likely be an overflow problem, so it will have to be handled by a human.
p = (min16*16L*clockCyclesPerMicrosecond() + (max16-min16)*(16L*clockCyclesPerMicrosecond())*angle/180L)/8L;
if (pin == 9) OCR1A = p;
if (pin == 10) OCR1B = p;
}
uint8_t Servo::read()
{
return angle;
}
uint8_t Servo::attached()
{
if (pin == 9 && attached9) return 1;
if (pin == 10 && attached10) return 1;
return 0;
}
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