/*
 * SimplePotPlay.c
 *
 * Created: 1/1/2013 3:57:11 PM
 *  Author: grist.carrigafoyl

 Testing reading analog pins.

 Using the reading to alter the flashing pattern on an LED.
 Only 8bit for now.

 */

#define F_CPU 8000000UL  //  8Mhz
#define timer_pot MUX0
#define photoresistor MUX1

#include <avr/io.h>
#include <util/delay.h>


// Prototypes
int main(void);
int read_adc(char pin);

int main(void)
{

    DDRB = _BV(PB1); // All input except PB1
    PORTB = _BV(PB0);  // Turn on the internal pullup resistor
    int timer_val,ambient_light, i;

    // How long the light stays on for. Simple constant multiplied by the pot reading
    int delay_time = 2; // ms
    //wake_up();
    while(1) {

        timer_val = read_adc(timer_pot);
        PORTB |= _BV(PB1);  // On
        for (i=0;i<timer_val;i++) {
            _delay_ms(delay_time);
        }

        ambient_light = read_adc(photoresistor);
        PORTB &= ~_BV(PB1); // Off
        for (i=0;i<ambient_light;i++) {
            _delay_ms(delay_time);
        }
    }
    return 0;
}


int read_adc(char pin)
{  // Read the analog value from the ADC input pin.
    // Speculative code based on    http://avrbasiccode.wikispaces.com/
    // When getting a 10bit value make sure you read the ADCL register before the ADCH register
    // collected_value = (ADCH << 8)|ADCL (representation only, have to get ADCL first as per above)
    int ret_val;

    // ADC settings. Check with datasheet that this is what you want
        ADCSRA |= _BV(ADEN) | // Enable ADC
        (_BV(ADPS1)) | // set prescaler to 128 (clock/128)
        (_BV(ADPS0)) |
        (_BV(ADPS2));

    // Assumes ADCSRA enabled and prescalars are set already
    //ADMUX |= _BV(ADLAR) | // AD result store in (more significant bit in ADCH)
    ADMUX |= _BV(pin); // Chose which AD input to read

    ADCSRA |= _BV(ADSC); // start a single conversion
    while (ADCSRA & _BV(ADSC)){} // wait until conversion is done
    // Throw away the first reading.
    ADCSRA |= _BV(ADSC); // start a single conversion
    while (ADCSRA & _BV(ADSC)){} // wait until conversion is done

    ret_val = ADCL; // only the high byte for now. I will want ADCL as well for 10bit

    ADCSRA &= ~(_BV(ADEN)); // Turn the ADC off
    return((ADCH << 8) | ret_val);
}