/*
	Analog1.C
	
	Written by Jeffrey J. Richardson	September 7, 2002
	
	Uses the MegaAVR-DEVelopment Board available from PRLLC
		with an ATmega163 controller operating at 6MHz.
		
	First Analog to Digital program.
		This program will setup the ADC...
		Read the value and Display it on Port C (forever)
*/

#include<mega163.h>
#include<stdio.h>

#define XTAL 6000000L
#define BAUD 9600

void init_serial(void);
void init_ports(void);
void init_ADC(void);
unsigned char read_ADC(void);

void main(void)
	{
	init_ports();					// setup the ports
	init_serial();					// setup the serial port
	init_ADC();					// setup the Analog Converter
	
	printf("Analog to Digital Converter.\n\r");
	
	while(1)					// do forever...
		{
		PORTC = ~read_ADC();			// monitor the ADC input and display it on the LEDs
      }
	}

unsigned char read_ADC(void)
	{
	unsigned char value;
	
	ADCSR = ADCSR | 0x40;			// start a conversion
	
	while( (ADCSR & 0x10) == 0 );		// wait for conversion to be completed
	
	value = ADCH;				// get the upper 8-bits
	ADCSR = ADCSR | 0x10;			// clear the flag
	
	return value;
	}
	
void init_serial(void)
	{
	unsigned int UBR;				// 16 bit variable to hold serial port calculations

	UBR = XTAL / 16 / BAUD - 1;			// calculate the load values
	UBRR = (unsigned char)(UBR & 0xFF);		// load the lower 8 bits
	UBRRHI = (unsigned char)(UBR >> 8);		// load the upper bits
	UCSRB = 0x18;					// enable transmit and receive
	}
	
void init_ports(void)
	{
	DDRC = 0xFF;					// setup PortC for output
	PORTC = 0x00; 
	}

void init_ADC(void)
	{
	ADMUX = 0x00;			// start by selecting channel 0
	ADMUX = ADMUX | 0x40;		// select the voltage reference
	ADMUX = ADMUX | 0x20;		// set for Left Justified
	
	ADCSR = 0x07;			// select the ADC clock frequency
	ADCSR = ADCSR | 0x80;		// enable the ADC
	}