wiring_analog.c

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/*
 *  Copyright (c) 2005-2006 David A. Mellis
 *
 *  This program 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 program 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 program.  If not, see <http://www.gnu.org/licenses/>.
 */
 

#include "wiring_private.h"
#include "pins_waspmote.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;
#elif defined(__AVR_ATmega1281__)
        } 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 if (digitalPinToTimer(pin) == TIMER3A) {
                // connect pwm to pin on timer 3, channel A
                sbi(TCCR3A, COM3A1);
                // set pwm duty
                OCR3A = val;    
        } else if (digitalPinToTimer(pin) == TIMER3B) {
                // connect pwm to pin on timer 3, channel B
                sbi(TCCR3A, COM3B1);
                // set pwm duty
                OCR3B = 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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