#define F_CPU 16000000UL
#include <avr/io.h>
#include <stdio.h>
#include <util/delay.h>
#include <string.h>
#include <avr/interrupt.h>
#include <stdlib.h>
#include <compat/twi.h>
#define MAX_TRIES 50
#define MCP23008_ID    0x40  // MCP23008 Device Identifier
#define MCP23008_ADDR  0x00  // MCP23008 Device Address
#define GPIO  0x09           // MCP23008 General Purpose I/O Register
#define OLAT  0x0A           // MCP23008 Output Latch Register
#define I2C_START 0
#define I2C_DATA 1
#define I2C_DATA_ACK 2
#define I2C_STOP 3
#define ACK 1
#define NACK 0
#define DATASIZE 32

#define SS 2
#define SS2 1
#define MOSI 3
#define MISO 4
#define SCK 5
#define TXD 1

#define ENABLE_SS PORTB &= ~(1 << SS)
#define DISABLE_SS PORTB |= (1 << SS)
#define ENABLE_SS2 PORTB &= ~(1 << PORTB1)  //pin 9 arduino = pin portb1
#define DISABLE_SS2 PORTB |= (1 << PORTB1)

#define  FOSC 16000000
#define  BAUD 9600
#define  MYUBBR FOSC/16/BAUD -1

#define UART_BUFF_SIZE 10


#define A 0
#define B 1

#define READ 1
#define WRITE 0

#define IODIR 0
#define OUTP_LATCH 10

void USART_Init(void);
void init(void);
uint8_t spi_tranceiver (uint8_t data);
void USART_Transmit(uint8_t data);
uint8_t adcSender(uint8_t data);

int16_t Temp_read(void);
void IOEXP_IODIR(uint8_t data);
void IOEXP_datalatch(uint8_t data);

uint8_t RX_buf[UART_BUFF_SIZE];
uint8_t TX_buf[UART_BUFF_SIZE];
uint8_t RX_index = 0;
uint8_t TX_index = 0;

ISR(USART_RX_vect)
{
	RX_buf[RX_index++] = UDR0;
	USART_Transmit(RX_buf[RX_index-1]);
}

int main(void)
{
	PORTC |= 0B00110000;
	init();
	i2c_init();
	/* Clearing buffers */
	memset(RX_buf,0,sizeof(RX_buf));
	memset(TX_buf,0,sizeof(TX_buf));
	Write_MCP23008(IODIR,0b00000000);
	Write_MCP23008(GPIO,0b00000000);    // Reset all the Output Port

	/* Enable interrupts */
	sei();
	/*
	/* set all pins of I/0 expander to output */
	//IOEXP_IODIR(0);
	/* set lower 4 bits (leds) high*/
//	IOEXP_datalatch(0x0f);
	//_delay_ms(1000);
	/* set higher 4 bits (leds) high
	IOEXP_datalatch(0xf0);
	_delay_ms(1000);*/

	while (1)
	{
		int8_t data = adcSender(0xf00);

		//IOEXP_datalatch(data); //set led
			//USART_Transmit('t');
			//USART_Transmit('=');
			USART_Transmit(data/10+48);
			USART_Transmit(data%10+48);
			USART_Transmit("/r");
			Write_MCP23008(GPIO,data);
		//USART_Transmit(data);    // give same value to USART
		_delay_ms(2000);
	}
}

void init()
{
	USART_Init();
	/* Set SS, MOSI and SCK output, all others input */
	DDRB = (1<<SS)|(1<<MOSI)|(1<<SCK)|(1 << PORTB1);
	/* LED PIN */
	DDRB |= (1 << PORTB0);
	/* Set TXD as an output */
	DDRD = (1 << TXD);

	/* Set the slave select pin (Active low) */
	DISABLE_SS;
	DISABLE_SS2;

	/* Enable SPI, Master, set clock rate fosc/16 */
	SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0);
}


// function to initialize UART
void USART_Init(void)
{
	// Set baud rate:
	UBRR0=103;                 //UBRR= Fosc /(16*9600) -1 =103.166= 103

	// enable receiver and transmitter
	UCSR0B |=(1<<RXEN0 |(1 <<TXEN0));

	// Set frame format : 8 data 2 stop bit

	UCSR0C = (1<<USBS0 )|(3<<UCSZ00);
}

void USART_Transmit( uint8_t data )
{
	/* Wait for empty transmit buffer */
	while ( !( UCSR0A & (1<<UDRE0)) );
	/* Put data into buffer, sends the data */
	UDR0 = data;
}

/* spi data buffer load and send */
uint8_t spi_tranceiver (uint8_t data)
{
	// Load data into the buffer
	SPDR = data;

	//Wait until transmission complete
	while(!(SPSR & (1<<SPIF) ));

	// Return received data
	return(SPDR);
}

uint8_t adcSender(uint8_t data)
{
	ENABLE_SS2;

	SPDR = data;
	while(!(SPSR & (1<<SPIF) ));

	//Read first 7 bits then second 5 bits
	uint8_t val0 = SPDR;
	uint8_t val1 = SPDR;
	DISABLE_SS2;
	unsigned short returnByte;

	uint16_t total0 = val0;
	returnByte = (total0 << 8);
	returnByte = returnByte | val1;
	returnByte = returnByte << 1;

	uint8_t totaleight = (returnByte >> 8);
	return totaleight;
}


unsigned char i2c_transmit(unsigned char type) {
	switch(type) {
		case I2C_START:    // Send Start Condition
		TWCR = (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
		break;
		case I2C_DATA:     // Send Data with No-Acknowledge
		TWCR = (1 << TWINT) | (1 << TWEN);
		break;
		case I2C_DATA_ACK: // Send Data with Acknowledge
		TWCR = (1 << TWEA) | (1 << TWINT) | (1 << TWEN);
		break;
		case I2C_STOP:     // Send Stop Condition
		TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
		return 0;
	}
	// Wait for TWINT flag set on Register TWCR
	while (!(TWCR & (1 << TWINT)));
	// Return TWI Status Register, mask the prescaler bits (TWPS1,TWPS0)
	return (TWSR & 0xF8);
}
char i2c_start(unsigned int dev_id, unsigned int dev_addr, unsigned char rw_type)
{
	unsigned char n = 0;
	unsigned char twi_status;
	char r_val = -1;
	i2c_retry:
	if (n++ >= MAX_TRIES) return r_val;
	// Transmit Start Condition
	twi_status=i2c_transmit(I2C_START);

	// Check the TWI Status
	if (twi_status == TW_MT_ARB_LOST) goto i2c_retry;
	if ((twi_status != TW_START) && (twi_status != TW_REP_START)) goto i2c_quit;
	// Send slave address (SLA_W)
	TWDR = (dev_id & 0xF0) | (dev_addr & 0x0E) | rw_type;
	// Transmit I2C Data
	twi_status=i2c_transmit(I2C_DATA);
	// Check the TWSR status
	if ((twi_status == TW_MT_SLA_NACK) || (twi_status == TW_MT_ARB_LOST)) goto i2c_retry;
	if (twi_status != TW_MT_SLA_ACK) goto i2c_quit;
	r_val=0;
	i2c_quit:
	return r_val;
}
void i2c_stop(void)
{
	unsigned char twi_status;
	// Transmit I2C Data
	twi_status=i2c_transmit(I2C_STOP);
}
char i2c_write(char data)
{
	unsigned char twi_status;
	char r_val = -1;
	// Send the Data to I2C Bus
	TWDR = data;
	// Transmit I2C Data
	twi_status=i2c_transmit(I2C_DATA);
	// Check the TWSR status
	if (twi_status != TW_MT_DATA_ACK) goto i2c_quit;
	r_val=0;
	i2c_quit:
	return r_val;
}

void Write_MCP23008(unsigned char reg_addr,unsigned char data)
{
	// Start the I2C Write Transmission
	i2c_start(MCP23008_ID,MCP23008_ADDR,TW_WRITE);
	// Sending the Register Address
	i2c_write(reg_addr);
	// Write data to MCP23008 Register
	i2c_write(data);
	// Stop I2C Transmission
	i2c_stop();
}


void i2c_init(void)
{
	// Initial ATMega328P TWI/I2C Peripheral
	TWSR = 0x00;         // Select Prescaler of 1
	// SCL frequency = 11059200 / (16 + 2 * 48 * 1) = 98.743 kHz
	TWBR = 0x30;        // 48 Decimal
}

/* IO expander latch  set */
void IOEXP_datalatch(uint8_t data)
{
	// Make slave select go low
	ENABLE_SS;
	/* Send device address + r/w */
	spi_tranceiver((1<<6)|WRITE);
	/* Send command */
	spi_tranceiver(OUTP_LATCH);
	spi_tranceiver(data);
	// Make slave select go high
	DISABLE_SS;

}