dial.c

/*
 * dial.c
 *
 * Driver for 3 analog dials, connected as follows:
 *
 * dial  | AVR
 *-------+-----------
 * size  | PF0 (ADC0)
 * speed | PF1 (ADC1)
 * press | PF2 (ADC2)
 *
 * Each input is a simple voltage divider between 0 and 5V, with 
 * a few discrete settings where the pot clicks.
 *
 * Copyright 2010 <freecutfirmware@gmail.com> 
 *
 * This file is part of Freecut.
 *
 * Freecut is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2.
 *
 * Freecut 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 General Public
 * License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Freecut. If not, see http://www.gnu.org/licenses/.
 *
 */

#include <avr/interrupt.h>
#include <avr/io.h>
#include <inttypes.h>
#include <stdio.h>
#include "dial.h"

static uint8_t channel = 0;

static unsigned char dial_adc[MAX_DIALS];
static unsigned char dial_steps[MAX_DIALS] = { 10, 5, 5 };

static int dial_setting( uint8_t dial )
{
    return( (dial_adc[dial] * (dial_steps[dial]-1) + 125) / 250 );
}

int dial_get_speed( void )
{
    return dial_setting( DIAL_SPEED );
}

int dial_get_pressure( void )
{
    return dial_setting( DIAL_PRESSURE );
}

int dial_get_size( void )
{
    return dial_setting( DIAL_SIZE );
}

void dial_poll( void )
{
    ADCSR |= (1 << ADIF);
    dial_adc[channel] = ADCH;
    if( ++channel == MAX_DIALS )
        channel = 0;
    ADMUX = (1 << ADLAR) | (1 << REFS0) | channel;
    ADCSRA |= (1 << ADSC);
}

void dial_init( void )
{
    ADMUX = (1 << ADLAR) | (1 << REFS0) | channel;
    ADCSRA = (1 << ADEN) | (1 << ADSC) | 7;
}