/*
 * uart_echo.c
 *
 * Created: 16.08.2018 17:39:49
 * Author : jens
 */ 

#include <stdio.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#define ARDUINO_NANO

#ifdef ARDUINO_NANO
#define F_CPU			(16000000UL)	// MHz
#else
#define F_CPU			(18432000UL)	// MHz
#endif
#define USART_BAUDRATE	9600UL
#define BAUD_PRESCALE	(((F_CPU / (USART_BAUDRATE * 16UL))) - 1)
#define TIMER_RELOAD	(0xFFFF-(F_CPU/1024/4-1))
static uint8_t rx_data;
static uint8_t count = 0;
volatile uint8_t msgCode = 0;
static uint8_t msgData = 0;
static uint8_t ledState = 0;
static int16_t adc_value[16];
static size_t adc_ch = 0;

enum MessageCode
{
	NOP=0,
	Command,
	Timer,
	AdcComplete,
	Error = 0xFF
};

ISR(ADC_vect)
{
	int16_t value_low = (int16_t)ADCL;
	int16_t value_high = (int16_t)ADCH;
	ADCSRA |= (1<<ADIF);
	int16_t value = value_high << 8 | value_low;
	
	if (((adc_value[adc_ch] - value) < -1) || ((adc_value[adc_ch] - value) > 1))
	{
		msgCode = AdcComplete;
		msgData = adc_ch;
	}
	
	adc_value[adc_ch] = value;
	adc_ch++;
	if (adc_ch == 16)
	{
		adc_ch = 0;
	}
	adc_start_conversion(adc_ch);
}

ISR(USART_RX_vect)
{
	rx_data = UDR0;
	
	msgCode = NOP;
	if (rx_data == ' ')
	{
		msgCode = Error;
	} 
	else if (rx_data >= '0' &&  rx_data <= '9')
	{
		msgCode = Command;
		msgData = rx_data;
	}
	count++;
}

ISR (TIMER1_OVF_vect)    // Timer1 ISR
{
	msgCode = Timer;
	TCNT1 = TIMER_RELOAD;
	ledState++;
	if (ledState == 4)
	{
		ledState = 0;
	} 
}

void uart_init()
{
	// Set baud rate
	UBRR0L  = (uint8_t)BAUD_PRESCALE;
	UBRR0H = (uint8_t)(BAUD_PRESCALE >> 8);
	
	// Enable receiver and transmitter
	UCSR0B = (1<<TXEN0)|(1<<RXEN0);
	
	// Enable RX interrupt
	UCSR0B |= (1<<RXCIE0);
	
}

void timer_init()
{
	
	TCNT1 = TIMER_RELOAD;

	TCCR1A = 0x00;
	TCCR1B = (1<<CS10) | (1<<CS12);  // Timer mode with 1024 prescaler
	TIMSK1 = (1 << TOIE1) ; // Enable timer1 overflow interrupt(TOIE1)
	
}

enum I2C
{
	I2C_START = 0x08,
	I2C_REPEATED_START = 0x10,
	I2C_SLA_ACK = 0x18,
	I2C_SLA_NACK = 0x20,
	I2C_DATA_ACK = 0x28,
	I2C_DATA_NACK = 0x30,
	I2C_LOST = 0x38,
	I2C_READ = 0x01,
	I2C_WRITE = 0x00
};

void i2c_init()
{
	TWBR = 0xFF;
	TWSR = 0x03;
}

void i2c_send(uint8_t addr, uint8_t rw, uint8_t *data, size_t size)
{
	TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN);
									// Send START condition
	do 
	{
		while (!(TWCR &(1<<TWINT)));	// Wait for TWINT Flag set. This indicates
										// that the START condition has been
										// transmitted.	
		if((TWSR & 0xF8) != I2C_START)
		{
			printf("Error I2C_START\n");
			break;
		}
		TWDR = addr<<1 | rw;					// Load SLA_W into TWDR Register. Clear
										// TWINT bit in TWCR to start transmission of
										// address.
		TWCR = (1<<TWINT) | (1<<TWEN);									
		while (!(TWCR &(1<<TWINT)));	// Wait for TWINT Flag set. This indicates
										// that the SLA+W has been transmitted, and
										// ACK/NACK has been received.


		if ((TWSR & 0xF8) != I2C_SLA_ACK)
		{
			printf("Error I2C_SLA_ACK\n");
			break;
		}
										// Check value of TWI Status Register. Mask
										// prescaler bits. If status different from
										// MT_SLA_ACK go to ERROR
		for (size_t i=0; i < size; i++)
		{
			
			TWDR = *(data++);
			TWCR = (1<<TWINT) | (1<<TWEN);
											// Load DATA into TWDR Register. Clear
											// TWINT bit in TWCR to start transmission of
											// data.

			while (!(TWCR & (1<<TWINT)));
											// Wait for TWINT Flag set. This indicates
											// that the DATA has been transmitted, and
											// ACK/NACK has been received}

			if ((TWSR & 0xF8) != I2C_DATA_ACK)
			{
				printf("Error I2C_DATA_ACK\n");
				break;
			}
											//	Check value of TWI Status Register. Mask
											//	prescaler bits. If status different from
											//	MT_DATA_ACK go to ERROR.
		}
	
	} while (0);
	TWCR = (1<<TWINT)| (1<<TWEN)|(1<<TWSTO);	// Transmit STOP condition.

}

void adc_init()
{
	PRR &= ~(1 << PRADC);
	ADCSRA |= (1 << ADEN) | 7;
}

void adc_start_conversion(int ch)
{
	ADMUX = (ADMUX & 0xF0) | (ch & 0x0F) | (1 << REFS0);
	ADCSRA |= (1 << ADSC) | (1 << ADIE);
}

int adc_is_fininshed()
{
	return (int)(0 == (ADCSRA & (1 << ADSC)));
}

int16_t adc_read()
{
	return adc_value;
	
	while(!adc_is_fininshed());
	uint16_t value_low = (uint16_t)ADCL;
	uint16_t value_high = (uint16_t)ADCH;
	ADCSRA |= (1<<ADIF);
	return value_high << 8 | value_low;
}

void uart_putc(char c)
{
	while((UCSR0A & (1<<UDRE0)) == 0)
	{
	}
	UDR0 = c;
}

int uart_putchar(char c, FILE *stream)
{
	uart_putc(c);
	if (c == 0x0A)
	{
		uart_putc(0x0D);
	}
	return 0;
}

void uart_puts(char const *str)
{
	while(*str)
	{
		char c = *(str++);
		uart_putc(c);
		if (c == 0x0A)
		{
			uart_putc(0x0D);
		}
	}	
}

void port_init()
{
	PORTB = PORTB | 0x03;
	DDRB = DDB1 | DDB2;
	
}
FILE uart_file = FDEV_SETUP_STREAM(uart_putchar, NULL, _FDEV_SETUP_WRITE);


int main(void)
{
	
    /* Replace with your application code */
	uart_init();
	timer_init();
	adc_init();
	i2c_init();
	
	stdout = &uart_file;
	printf("UART test version 1.0\n\n");

	uint8_t write_dac_full[] = {0x40, 0x00, 0x00};		// 6.1 Write Volatile DAC Register (C2:C0 = ‘00x’)
	i2c_send(0x60, I2C_WRITE, write_dac_full, sizeof(write_dac_full));

	sei();
	adc_start_conversion(adc_ch);
	while (1) 
    {
	
		if (msgCode)
		{
			cli();
			uint8_t _msgCode = msgCode;
			uint8_t _msgData = msgData;
			sei();
			
			switch(_msgCode)
			{
				case Command:
				printf("Command : %c\n", _msgData);
				uint8_t write_dac[] = {0x00+(_msgData-'0'), 0x00};					// 6.2 Write Volatile Memory (C2:C0 = ‘010’)
				i2c_send(0x60, I2C_WRITE, write_dac, sizeof(write_dac));
				break;
			
				case AdcComplete:
				{
					size_t ch = _msgData;
					if (ch == 6)
					{
						printf("ADC=%d\n", adc_value[ch]);
					}
				}
				break;

				case Timer:
				switch(ledState)
				{
					case 0:
					DDRB = (DDRB & 0xFC) | 0x00;
					printf("----------- Timer -----------\n");
					break;
					case 1:
					DDRB = (DDRB & 0xFC) | 0x01;
					break;
					case 2:
					DDRB = (DDRB & 0xFC) | 0x03;
					break;
					case 3:
					DDRB = (DDRB & 0xFC) | 0x02;
					break;
				}
				break;

				case Error:
				printf("Error!!!\n");
				break;
			}
		}
    }
}