#define F_CPU 6000000UL
#define BAUD 9600

#define UBRR F_CPU/16/BAUD-1

#define DD_MOSI PB3
#define DD_MISO PB5
#define DD_SCK PB5
#define DDR_SPI DDRB
#define SS PB2

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


void SPI_SlaveInit(void);
char SPI_SlaveReceive(void);
void usart_init(unsigned int);
void usart_tx(unsigned char);

volatile uint8_t plant[] = {0x41,0x42,0x43,0x44,0x45,0x46};


/* Limits
 * 		Low	Normal
 * Chili 	3.83V	2.85V
 *
 * */

int main()
{
	ADMUX = (1<<REFS0)|(1<<ADLAR); // Set left-adj, AREF as voltage reference and use channel 0
	
	usart_init(UBRR);
	SPI_SlaveInit();

	//ADCSRB = ~(7<<ADTS0);
	//ADCSRA = (1<<ADEN)|(1<<ADATE)|(1<<ADIE)|(1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0); // prescaler 128
	ADCSRA = (1<<ADEN)|(1<<ADIE)|(1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0); // prescaler 128
	
	
	sei();
	while(1)
	{
//		ADCSRA |= (1<<ADSC);
		_delay_ms(1000);
	}
}

void usart_init(unsigned int baud)
{
	UBRR0H = (unsigned char)(baud>>8);
	UBRR0L = (unsigned char)baud;
	UCSR0B = (1<<RXEN0)|(1<<TXEN0)|(1<<RXCIE0);
	
	// Setting up frame-format
	UCSR0C = (1<<UCSZ01)|(1<<UCSZ00); // 8 data-bits
	UCSR0C |= (1<<USBS0); // 2 stop-bits
	UCSR0C |= (1<<UPM01); // parity even

}

void usart_tx(unsigned char data)
{
	while (!(UCSR0A & (1<<UDRE0)))
	;
	UDR0 = data;
}

void SPI_SlaveInit(void)
{
        DDR_SPI = (1<<1)|(1<<DD_MISO); // MISO is output / PINB0 for debugging
        SPCR = (1<<SPIE)|(1<<SPE); // enable SPI and activate interrupt
}

ISR(SPI_STC_vect)
{
	if (SPDR == 0x20)
	{
		PORTB |= (1<<1);	// switch ON LED when sent value equals 0x20
		SPDR = 0xff;
	}
	else if (SPDR == 0x21)
	{
		PORTB &= ~(1<<1);	// switch OFF LED when sent value equals 0x21
		SPDR = 0xee;
	}
}

ISR(ADC_vect)
{
	usart_tx(0x0A);
	usart_tx(0x0D);
}