#include "header.h"

// Table 14-6. Port C Pins Alternate Functions
// - PC0 -> ADC0 (ADC Input Channel 0)
//       -> PCINT8 (Pin Change Interrupt 8)
//
// 24.2 : The ADC generates a 10-bit result which is presented in the ADC Data Registers, ADCH and ADCL
//
// START A CONVERSTION in single conversion mode :
// - disabling the Power Reduction ADC bit, PRADC
// - writing a logical one to the ADC Start Conversion bit, ADSC

void adc_init(uint8_t prescaler_value) {
    ADMUX = (1 << REFS0);									// Table 24-3 : set voltage reference, AVCC with external capacitor at AREF pin
    ADCSRA = (1 << ADEN); 									// 24.9.2 : enable ADC
	ADCSRA |= (1 << ADATE); 								// 24.9.2 : enable Auto Trigger -> it will start a conversion on the selected channel in ADMUX when the selected source (in ADCSRB) is triggered
	ADCSRA |= (1 << ADIE);								 	// 24.9.2 : enable ADC Interrupt
    ADCSRA |= ADC_PRESCALE_SET(prescaler_value);			// Table 24-5 : prescaler ADC

	ADCSRB = ADC_TRIGGER_TIMER_1_COMPARE_B;					// Table 24-6 : ADC Auto Trigger Source
	ADMUX = (ADMUX & 0b11110000) | (adc_channel & 0b1111);	// Table 24-4 : Select ADC channel 0, (Table 14-6 : alternate function for RV1 on PC0 -> ADC0)
}


void adc_print_hex(uint8_t value) {
	char buffer[3] = {0};
	int_to_hex_string(value, buffer, 2);
	uart_printstr_endl(buffer);
}

ISR(ADC_vect) {												// Table 12-6 : interrupt vector for ADC Conversion Complete
	uint16_t value = ADC;
	adc_print_hex(value);
}