/*
 * ES_Prak_01.c
 *
 * Created: 07.04.2014 14:42:04
 *  Author: Ehlers
 */

/*
 * Definitions
 */

#define F_CPU 1000000UL

#define I2C_DEVICE_ADDRESS (0xE0)

#define TEST_LED_DISPLAY 1
#define TEST_ADC_READ 0
#define TEST_I2C_READREGISTER 1

#define BUFFSIZE 20

/*
 * Includes
 */

#include <avr/io.h>
// include this to get access to uint8_t, uint16_t and so on...
#include <stdint.h>
#include <stdio.h>
#include <util/delay.h>

// include the header for I2C communication
#include "i2c_master.h"
#include "uart.h"


/*
 * Exercise 01
 */

void led_init()
{
	// configure Port B as output (set all bits in DDRB high)  
	DDRB = ~0; //0b11111111
}

void led_display(uint16_t value)
{
	uint8_t mask = 0;
	// create mask
	for (uint8_t i = value / 128; i >= 0; i--)
	{
		// shift the bit mask and set the lsb high
		mask = (mask << 1) | 1;
	}
	// set the output of Port B
	PINB = mask;
}

/*
 * Exercise 02
 */

void adc_init()
{
	// set prescaler to 128
	ADCSRA = (1 << ADEN) | (1 << ADPS0) | (1 << ADPS1) | (1 << ADPS2);

	// set AVCC (VCC = 5V) as reference
	ADMUX = (1 << REFS0);

	// start blind conversion
	adc_read(0);
}

uint16_t adc_read(uint8_t channel)
{
	// create mux mask
	uint8_t muxMask = (1 << MUX0) | (1 << MUX1) | (1 << MUX2) | (1 << MUX3) | (1 << MUX4);
	// clear all channel bits
	ADMUX &= ~muxMask;
	// set the passed channel (and clear not allowed bits)
	ADMUX |= (channel & muxMask);

	// start conversion
	ADCSRA |= (1 << ADSC);
	// wait until the conversion is complete
	while (ADCSRA & (1 << ADSC));

	// read value of the low byte
	uint16_t value = ADCL;
	// add the high byte (and shift its value)
	value |= (ADCH << 8);
	return value;
}

/*
 * Exercise 03
 */

void i2c_writeRegister(uint8_t add, uint8_t reg, uint8_t dat)
{
	// connect to address add
	i2c_start(add & ~1);

	// chose register to reg
	i2c_write(reg);
	// write dat into register reg
	i2c_write(dat);

	// stop connection
	i2c_stop();
}

uint8_t i2c_readRegister(uint8_t add, uint8_t reg)
{
	// connect to address add
	i2c_start(add & ~1);
	// chose register to reg
	i2c_write(reg);

	// start read connection
	i2c_rep_start(add | 1);
	uint8_t dat = 0;
	// read value from reg into dat
	i2c_readNak(&dat);

	// stop connection
	i2c_stop();
	// return read data
	return dat;
}

int main(void)
{
	// Initialization
	sei();
	uart_init();

	// initialize the AD converter
	adc_init();

	// declare string buffer
	char buff[BUFFSIZE];

	while(1)
	{
		#if TEST_LED_DISPLAY == 1

		// test led_display
		for (uint16_t testNum = 0; testNum < 1024; testNum++)
		{
			led_display(testNum);
			_delay_ms(8);
		}

		#elif TEST_ADC_READ == 1

		// test adc_read
		led_display(adc_read(0));

		#elif TEST_I2C_READREGISTER == 1

		// test i2c_readRegister
		uint16_t distance = i2c_readRegister(I2C_DEVICE_ADDRESS, 3);
		distance |= (i2c_readRegister(I2C_DEVICE_ADDRESS, 2) << 8);

		snprintf(buf, BUFFSIZE, "%u\n", distance);
		uart_sendstring(buff);
		_delay_ms(1024);

		#else

		// TODO

		#endif
	}
}