#define F_CPU 16000000
#define F_SCL 100000 // 100kHz

#include <asf.h>
#include <util/delay.h>
#include "lcd.h"
#include <stdio.h>

static int lcd_putchar(char c, FILE *stream){
	LCDCharacterOut(c);
	return 0;
}
static FILE mystdout = FDEV_SETUP_STREAM(lcd_putchar, NULL,_FDEV_SETUP_WRITE);

volatile unsigned char countI2C = 0;
volatile unsigned char deviceI2C = 0;

// ADS1114 Slave Adresse
unsigned char SLA_W_ADS1114 = 0x90;
unsigned char SLA_R_ADS1114 = 0x91;

unsigned int Messwert_sum = 0;
unsigned int Messwert_H = 0;
unsigned int Messwert_L = 0;
int i = 0;

ISR(TWI0_vect) {
	if(deviceI2C == 0)
	{
		switch (countI2C) 
		{
			case 0: 
			{							
				switch (TWSR0) 
				{
					case 0x08:															// Start has been transmitted
					TWDR0 = SLA_W_ADS1114;												// Slave Adresse Write 
					TWCR0 = (1 << TWINT) | (1 << TWEN) | (1 << TWIE);
					break;
					
					case 0x18:															// Adr + W has been transmitted
					TWDR0 = 0b00000001;													// Pointer Register, 0x01 =Config Register
					TWCR0 = (1<<TWINT) | (1<<TWEN) | (1 << TWIE);
					break;
					
					case 0x28: 
						if (i==0)
						{
						TWDR0 = 0b11000001;												// Byte 1(MSB), Single Conversion, AIN 0 = Input & AINx = GND, FSR +/- 6.144V, Single shot
						i++;					
						TWCR0 = (1<<TWINT) | (1<<TWEN) | (1 << TWIE)|(1<<TWEA);
						break;
						}
						else if (i==1)
						{
						i=0;
						TWDR0 =	0b10000011;												// Byte 2(LSB), 128 SPS, Comp disable and Alert Disable
						TWCR0 = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO) | (1 << TWIE);		// Stop
						_delay_ms(5);
						TWCR0 = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN) | (1 << TWIE);		// START
						countI2C++;
						}
					
					default:
					TWCR0 = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO) | (1 << TWIE);
					break;
				}
				break;
			}
			case 1: 
			{ 
				switch (TWSR0)
				{
					case 0x08:														// Start has been transmitted
					TWDR0 = SLA_W_ADS1114;											// Slave Adresse Write 
					TWCR0 = (1 << TWINT) | (1 << TWEN) | (1 << TWIE);
					break;
					
					case 0x18:														// Adr + W has been transmitted
					TWDR0 = 0b00000000;												// Pointer Register, 0x00 = Conversion Register
					TWCR0 = (1<<TWINT) | (1<<TWEN) | (1 << TWIE);
					break;
					
					case 0x28:														// Data has been transmitted
					countI2C++;
					TWCR0 = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO) | (1 << TWIE);		// STOP
					_delay_ms(5);					
					TWCR0 = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN) | (1 << TWIE);		// START
					break;
					
					default:
					TWCR0 = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO) | (1 << TWIE);
					break;					
				}
				break;
			}
			case 2: 
			{ 
				switch (TWSR0) 
				{
					case 0x08:														// Start has been transmitted
					TWDR0 = SLA_R_ADS1114;											// Slave Adresse Read
					TWCR0 = (1 << TWINT) | (1 << TWEN) | (1 << TWIE);
					break;
					
					case 0x40:														// Adr + R has been transmitted	
					TWCR0 = (1<<TWINT) | (1 << TWEA) | (1<<TWEN) | (1 << TWIE);
					break;
					
					case 0x50:														// 1 Byte (MSB) lesen							
					Messwert_H = TWDR0;												
					TWCR0 = (1<<TWINT) | (1<<TWEN) | (1 << TWIE);
					break;
					
					case 0x58:														// 2 Byte (LSB) lesen	
					Messwert_L = TWDR0;
					Messwert_sum = Messwert_H<<8 | Messwert_L>>0;					// MSB und LSB an die richtige stelle schieben
					
					LCDCursorHome();
					printf("Spannung: %.2f V",Messwert_sum *0.0001875);				// temp sum in fließkommazahl umrechnen und ausgeben

					countI2C = 0;
					TWCR0 = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO) | (1 << TWIE);		// STOP
					_delay_ms(5);
					TWCR0 = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN) | (1 << TWIE);		// START
					break;
					
					default:
					TWCR0 = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO) | (1 << TWIE);
					break;					
				}
				break;
			}
		}
	}
}

int main (void)
{
	LCDinit();
	LCDCursorOff();
	stdout = &mystdout;
	
	TWSR0 = 0;
	TWBR0 = ((F_CPU / F_SCL) - 16) / 2;
	
	sei();
	TWCR0 = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO) | (1 << TWIE);		// STOP
	_delay_ms(5);
	TWCR0 = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN) | (1 << TWIE);		// START

	while (1){
		
	}
	
}