#define F_CPU 3686411UL
#include <avr/io.h>
#include <util/delay.h>
#include <stdlib.h>
#include <avr/interrupt.h> 



void USART_vInit(void){
	UCSRB |= (1<<TXEN)|(1<<RXEN);
	UCSRC |= (1<<URSEL)|(1 << UCSZ1)|(1 << UCSZ0);   // Asynchron 8N0 
 
	UBRRH = 0x00;
	UBRRL = 0x17;
}


int uart_putc(unsigned char c)
{
    while (!(UCSRA & (1<<UDRE)))  /* warten bis Senden moeglich */
    {
    }
	UDR = c;                      /* sende Zeichen */
    return 0;
}


void uart_puts (char *s)
{
    while (*s)
    {   /* so lange *s != '\0' also ungleich dem "String-Endezeichen" */
        uart_putc(*s);
        s++;
    }
}



char s[15];
volatile uint16_t max_adc_value = 0;	// Maximal-Wert des ADC innerhalb eines send-zyklus
volatile uint8_t ADC_Counter = 0;				// Über wie viele Messungen wird das max ermittelt?

int main(void)
{
        	// Initialise USART
		USART_vInit();

		// Set up 8bit Timer2 for Data send interval
  		TCCR2 |= (1<<CS20)|(1<<CS21)|(1<<CS22);		// prescaler 1024
		TCCR2 |= (1<<WGM21);				// Activate Mode3: CTC on compare match with OCR2	
		OCR2 = 180;							// 72:20ms; 180:50ms; 360:100ms;
		TIMSK |= (1<<OCIE2);				// enable timer2 compare match interrupt
		
		// Set up ADC
		ADCSRA |= (1<<ADPS2) | (1<<ADPS0); 	// ADC prescaler 32
		ADMUX |= (1<<REFS0);				// reference is 5V VCC
		ADMUX &= ~((1<<MUX0) | (1<<MUX1) | (1<<MUX2) | (1<<MUX3));  // ADC Kanal 0
		ADCSRA |= (1<<ADFR);				// ADC free running mode
		ADCSRA |= (1<<ADEN);    			// enable ADC
		ADCSRA |= (1<<ADIE);				// enable ADC interrupt
		ADCSRA |= (1<<ADSC);				// start ADC FR measurements
		
		sei();					// enable global interrupts

  while(1){			// loop forever
  }

return 0;
}


// Interrupt on ADC conversion complete
ISR(ADC_vect)
{	
	// Es werden nur max-Werte des ADC gespeichert!
	if (max_adc_value<ADCW) (max_adc_value=ADCW);
	ADC_Counter++;
}


// Interrupt on timer0 overflow - send data
ISR(TIMER2_COMP_vect)                          // every 50ms
{
	//top-value of max_adc_value can only be 1023
	if (max_adc_value>1023) (max_adc_value=1023);
	
	//uart_puts("$1;1;;"); //$ + Channel No + Status No + No Timestamp
	uart_puts( itoa( ADC_Counter, s, 10 ) );
	uart_puts(";");
	uart_puts( itoa( max_adc_value, s, 10 ) );
	uart_puts(";0\r\n");

	//set counters back to 0;
	max_adc_value = 0;
	ADC_Counter = 0;
}