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134 lines
3.5 KiB
C++
Executable File
134 lines
3.5 KiB
C++
Executable File
#include <avr/interrupt.h>
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#include <wiring.h>
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#include <Servo.h>
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/*
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Servo.h - Hardware Servo Timer Library
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Author: Jim Studt, jim@federated.com
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Copyright (c) 2007 David A. Mellis. All right reserved.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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uint8_t Servo::attached9 = 0;
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uint8_t Servo::attached10 = 0;
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void Servo::seizeTimer1()
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{
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uint8_t oldSREG = SREG;
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cli();
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TCCR1A = _BV(WGM11); /* Fast PWM, ICR1 is top */
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TCCR1B = _BV(WGM13) | _BV(WGM12) /* Fast PWM, ICR1 is top */
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| _BV(CS11) /* div 8 clock prescaler */
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;
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OCR1A = 3000;
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OCR1B = 3000;
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ICR1 = clockCyclesPerMicrosecond()*(20000L/8); // 20000 uS is a bit fast for the refresh, 20ms, but
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// it keeps us from overflowing ICR1 at 20MHz clocks
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// That "/8" at the end is the prescaler.
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#if defined(__AVR_ATmega168__)
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TIMSK1 &= ~(_BV(OCIE1A) | _BV(OCIE1B) | _BV(TOIE1) );
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#else
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TIMSK &= ~(_BV(TICIE1) | _BV(OCIE1A) | _BV(OCIE1B) | _BV(TOIE1) );
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#endif
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SREG = oldSREG; // undo cli()
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}
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void Servo::releaseTimer1() {}
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#define NO_ANGLE (0xff)
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Servo::Servo() : pin(0), angle(NO_ANGLE) {}
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uint8_t Servo::attach(int pinArg)
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{
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return attach(pinArg, 544, 2400);
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}
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uint8_t Servo::attach(int pinArg, int min, int max)
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{
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if (pinArg != 9 && pinArg != 10) return 0;
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min16 = min / 16;
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max16 = max / 16;
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pin = pinArg;
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angle = NO_ANGLE;
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digitalWrite(pin, LOW);
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pinMode(pin, OUTPUT);
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if (!attached9 && !attached10) seizeTimer1();
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if (pin == 9) {
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attached9 = 1;
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TCCR1A = (TCCR1A & ~_BV(COM1A0)) | _BV(COM1A1);
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}
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if (pin == 10) {
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attached10 = 1;
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TCCR1A = (TCCR1A & ~_BV(COM1B0)) | _BV(COM1B1);
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}
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return 1;
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}
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void Servo::detach()
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{
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// muck with timer flags
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if (pin == 9) {
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attached9 = 0;
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TCCR1A = TCCR1A & ~_BV(COM1A0) & ~_BV(COM1A1);
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pinMode(pin, INPUT);
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}
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if (pin == 10) {
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attached10 = 0;
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TCCR1A = TCCR1A & ~_BV(COM1B0) & ~_BV(COM1B1);
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pinMode(pin, INPUT);
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}
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if (!attached9 && !attached10) releaseTimer1();
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}
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void Servo::write(int angleArg)
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{
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uint16_t p;
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if (angleArg < 0) angleArg = 0;
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if (angleArg > 180) angleArg = 180;
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angle = angleArg;
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// bleh, have to use longs to prevent overflow, could be tricky if always a 16MHz clock, but not true
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// That 8L on the end is the TCNT1 prescaler, it will need to change if the clock's prescaler changes,
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// but then there will likely be an overflow problem, so it will have to be handled by a human.
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p = (min16*16L*clockCyclesPerMicrosecond() + (max16-min16)*(16L*clockCyclesPerMicrosecond())*angle/180L)/8L;
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if (pin == 9) OCR1A = p;
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if (pin == 10) OCR1B = p;
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}
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uint8_t Servo::read()
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{
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return angle;
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}
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uint8_t Servo::attached()
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{
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if (pin == 9 && attached9) return 1;
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if (pin == 10 && attached10) return 1;
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return 0;
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}
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