/*
 * ADC.c
 *
 * Created: 05/04/2025 11:08:43
 * Author : Paulo H. Langone
 * Board  : LabGenios Nano
 */ 

#define F_CPU 16000000UL

#include <stdio.h>
#include <avr/io.h>
#include <util/delay.h>
#include "usart.h"

/*
 *	@brief Initialize ADC 
 */
void adc_init()
{
	// AVCC with external capacitor at AREF pin
	ADMUX |= (1 << REFS0);
	
	// ADC Enable and ADPS = 128 (111)
	ADCSRA |= ((1 << ADEN) | (7 << ADPS0));
	
	// Get first conversion and do nothing
	ADCSRA |= (1 << ADSC);
	while(ADCSRA & (1 << ADSC));
}

/*
 *	@brief Performs an ADC read in a selected channel
 *  @param uint8_t channel channel to be read
 *  @return read from the selected ADC channel
 */
uint16_t adc_read(uint8_t channel)
{	
	// Wait for any possible conversion to end
	while(ADCSRA & (1 << ADSC));	
	
	// Select channel
	ADMUX |= (channel << MUX0);
	
	// Get conversion
	ADCSRA |= (1 << ADSC);
	while(ADCSRA & (1 << ADSC));
	
	// Return conversion
	return (ADCL | (ADCH << 8));
}

/*
 *	Main function
 */
int main(void)
{
	adc_init();									// Initialize ADC					
	usart_init(9600, SERIAL_8N1);				// Initialize USART
	
	uint16_t trimpot;					
	char msg[20];
	
	while (1)
	{
		trimpot = adc_read(6);					// Perform a read at channel 6 (trimpot from LabGenios nano board)
		sprintf(msg, "ADC: %d\r\n", trimpot);	// Format the message
		usart_write_str(msg);					// Send the message via USART
		_delay_ms(500);							// Wait 500ms for next read
	}
}