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/*
wiring_analog.c - analog input and output
Part of Arduino - http://www.arduino.cc/
Copyright (c) 2005-2006 David A. Mellis
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., 59 Temple Place, Suite 330,
Boston, MA 02111-1307 USA
$Id: wiring.c 248 2007-02-03 15:36:30Z mellis $
*/
#include "wiring_private.h"
#include "pins_arduino.h"
int analogRead(uint8_t pin)
{
uint8_t low, high, ch = analogInPinToBit(pin);
// the low 4 bits of ADMUX select the ADC channel
ADMUX = (ADMUX & (unsigned int) 0xf0) | (ch & (unsigned int) 0x0f);
// without a delay, we seem to read from the wrong channel
//delay(1);
// start the conversion
sbi(ADCSRA, ADSC);
// ADSC is cleared when the conversion finishes
while (bit_is_set(ADCSRA, ADSC));
// we have to read ADCL first; doing so locks both ADCL
// and ADCH until ADCH is read. reading ADCL second would
// cause the results of each conversion to be discarded,
// as ADCL and ADCH would be locked when it completed.
low = ADCL;
high = ADCH;
// combine the two bytes
return (high << 8) | low;
}
// Right now, PWM output only works on the pins with
// hardware support. These are defined in the appropriate
// pins_*.c file. For the rest of the pins, we default
// to digital output.
void analogWrite(uint8_t pin, int val)
{
// We need to make sure the PWM output is enabled for those pins
// that support it, as we turn it off when digitally reading or
// writing with them. Also, make sure the pin is in output mode
// for consistenty with Wiring, which doesn't require a pinMode
// call for the analog output pins.
pinMode(pin, OUTPUT);
if (digitalPinToTimer(pin) == TIMER1A) {
// connect pwm to pin on timer 1, channel A
sbi(TCCR1A, COM1A1);
// set pwm duty
OCR1A = val;
} else if (digitalPinToTimer(pin) == TIMER1B) {
// connect pwm to pin on timer 1, channel B
sbi(TCCR1A, COM1B1);
// set pwm duty
OCR1B = val;
#if defined(__AVR_ATmega168__)
} else if (digitalPinToTimer(pin) == TIMER0A) {
// connect pwm to pin on timer 0, channel A
sbi(TCCR0A, COM0A1);
// set pwm duty
OCR0A = val;
} else if (digitalPinToTimer(pin) == TIMER0B) {
// connect pwm to pin on timer 0, channel B
sbi(TCCR0A, COM0B1);
// set pwm duty
OCR0B = val;
} else if (digitalPinToTimer(pin) == TIMER2A) {
// connect pwm to pin on timer 2, channel A
sbi(TCCR2A, COM2A1);
// set pwm duty
OCR2A = val;
} else if (digitalPinToTimer(pin) == TIMER2B) {
// connect pwm to pin on timer 2, channel B
sbi(TCCR2A, COM2B1);
// set pwm duty
OCR2B = val;
#else
} else if (digitalPinToTimer(pin) == TIMER2) {
// connect pwm to pin on timer 2, channel B
sbi(TCCR2, COM21);
// set pwm duty
OCR2 = val;
#endif
} else if (val < 128)
digitalWrite(pin, LOW);
else
digitalWrite(pin, HIGH);
}
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