root / arduino-1.0 / hardware / arduino / cores / arduino / wiring_analog.c @ 58d82c77
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/*
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wiring_analog.c - analog input and output
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Part of Arduino - http://www.arduino.cc/
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Copyright (c) 2005-2006 David A. Mellis
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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
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Public License along with this library; if not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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Boston, MA 02111-1307 USA
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Modified 28 September 2010 by Mark Sproul
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$Id: wiring.c 248 2007-02-03 15:36:30Z mellis $
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*/
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#include "wiring_private.h" |
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#include "pins_arduino.h" |
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uint8_t analog_reference = DEFAULT; |
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void analogReference(uint8_t mode)
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{
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// can't actually set the register here because the default setting
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// will connect AVCC and the AREF pin, which would cause a short if
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// there's something connected to AREF.
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analog_reference = mode; |
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} |
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int analogRead(uint8_t pin)
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{
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uint8_t low, high; |
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#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
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if (pin >= 54) pin -= 54; // allow for channel or pin numbers |
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#elif defined(__AVR_ATmega32U4__)
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if (pin >= 18) pin -= 18; // allow for channel or pin numbers |
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#else
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if (pin >= 14) pin -= 14; // allow for channel or pin numbers |
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#endif
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#if defined(__AVR_ATmega32U4__)
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pin = analogPinToChannel(pin); |
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ADCSRB = (ADCSRB & ~(1 << MUX5)) | (((pin >> 3) & 0x01) << MUX5); |
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#elif defined(ADCSRB) && defined(MUX5)
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// the MUX5 bit of ADCSRB selects whether we're reading from channels
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// 0 to 7 (MUX5 low) or 8 to 15 (MUX5 high).
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ADCSRB = (ADCSRB & ~(1 << MUX5)) | (((pin >> 3) & 0x01) << MUX5); |
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#endif
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// set the analog reference (high two bits of ADMUX) and select the
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// channel (low 4 bits). this also sets ADLAR (left-adjust result)
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// to 0 (the default).
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#if defined(ADMUX)
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ADMUX = (analog_reference << 6) | (pin & 0x07); |
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#endif
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// without a delay, we seem to read from the wrong channel
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//delay(1);
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#if defined(ADCSRA) && defined(ADCL)
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// start the conversion
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sbi(ADCSRA, ADSC); |
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// ADSC is cleared when the conversion finishes
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while (bit_is_set(ADCSRA, ADSC));
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// we have to read ADCL first; doing so locks both ADCL
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// and ADCH until ADCH is read. reading ADCL second would
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// cause the results of each conversion to be discarded,
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// as ADCL and ADCH would be locked when it completed.
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low = ADCL; |
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high = ADCH; |
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#else
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// we dont have an ADC, return 0
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low = 0;
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high = 0;
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#endif
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// combine the two bytes
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return (high << 8) | low; |
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} |
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// Right now, PWM output only works on the pins with
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// hardware support. These are defined in the appropriate
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// pins_*.c file. For the rest of the pins, we default
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// to digital output.
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void analogWrite(uint8_t pin, int val) |
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{
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// We need to make sure the PWM output is enabled for those pins
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// that support it, as we turn it off when digitally reading or
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// writing with them. Also, make sure the pin is in output mode
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// for consistenty with Wiring, which doesn't require a pinMode
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// call for the analog output pins.
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pinMode(pin, OUTPUT); |
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if (val == 0) |
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{
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digitalWrite(pin, LOW); |
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} |
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else if (val == 255) |
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{
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digitalWrite(pin, HIGH); |
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} |
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else
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{
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switch(digitalPinToTimer(pin))
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{
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// XXX fix needed for atmega8
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#if defined(TCCR0) && defined(COM00) && !defined(__AVR_ATmega8__)
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case TIMER0A:
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// connect pwm to pin on timer 0
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sbi(TCCR0, COM00); |
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OCR0 = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR0A) && defined(COM0A1)
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case TIMER0A:
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// connect pwm to pin on timer 0, channel A
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sbi(TCCR0A, COM0A1); |
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OCR0A = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR0A) && defined(COM0B1)
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case TIMER0B:
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// connect pwm to pin on timer 0, channel B
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sbi(TCCR0A, COM0B1); |
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OCR0B = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR1A) && defined(COM1A1)
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case TIMER1A:
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// connect pwm to pin on timer 1, channel A
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sbi(TCCR1A, COM1A1); |
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OCR1A = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR1A) && defined(COM1B1)
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case TIMER1B:
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// connect pwm to pin on timer 1, channel B
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sbi(TCCR1A, COM1B1); |
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OCR1B = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR2) && defined(COM21)
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case TIMER2:
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// connect pwm to pin on timer 2
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sbi(TCCR2, COM21); |
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OCR2 = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR2A) && defined(COM2A1)
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case TIMER2A:
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// connect pwm to pin on timer 2, channel A
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sbi(TCCR2A, COM2A1); |
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OCR2A = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR2A) && defined(COM2B1)
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case TIMER2B:
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// connect pwm to pin on timer 2, channel B
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sbi(TCCR2A, COM2B1); |
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OCR2B = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR3A) && defined(COM3A1)
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case TIMER3A:
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// connect pwm to pin on timer 3, channel A
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sbi(TCCR3A, COM3A1); |
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OCR3A = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR3A) && defined(COM3B1)
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case TIMER3B:
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// connect pwm to pin on timer 3, channel B
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sbi(TCCR3A, COM3B1); |
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OCR3B = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR3A) && defined(COM3C1)
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case TIMER3C:
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// connect pwm to pin on timer 3, channel C
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sbi(TCCR3A, COM3C1); |
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OCR3C = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR4A) && defined(COM4A1)
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case TIMER4A:
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// connect pwm to pin on timer 4, channel A
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sbi(TCCR4A, COM4A1); |
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OCR4A = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR4A) && defined(COM4B1)
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case TIMER4B:
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// connect pwm to pin on timer 4, channel B
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sbi(TCCR4A, COM4B1); |
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OCR4B = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR4A) && defined(COM4C1)
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case TIMER4C:
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// connect pwm to pin on timer 4, channel C
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sbi(TCCR4A, COM4C1); |
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OCR4C = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR4A) && defined(COM4D1)
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case TIMER4D:
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// connect pwm to pin on timer 4, channel D
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sbi(TCCR4A, COM4D1); |
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OCR4D = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR5A) && defined(COM5A1)
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case TIMER5A:
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// connect pwm to pin on timer 5, channel A
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sbi(TCCR5A, COM5A1); |
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OCR5A = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR5A) && defined(COM5B1)
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case TIMER5B:
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// connect pwm to pin on timer 5, channel B
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sbi(TCCR5A, COM5B1); |
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OCR5B = val; // set pwm duty
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break;
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#endif
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#if defined(TCCR5A) && defined(COM5C1)
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case TIMER5C:
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// connect pwm to pin on timer 5, channel C
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sbi(TCCR5A, COM5C1); |
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OCR5C = val; // set pwm duty
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break;
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#endif
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case NOT_ON_TIMER:
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default:
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if (val < 128) { |
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digitalWrite(pin, LOW); |
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} else {
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digitalWrite(pin, HIGH); |
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} |
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} |
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} |
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} |