[ES] Übung 2

/*
 * 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
    }
}