#include <stdbool.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#define F_CPU 20000000UL  //20 MHz
#include <util/delay.h>

/* 7-Segment display: */
#define NUM_DIGITS 3U  //3 Digits
#define DIGIT_TENS 2U  //left
#define DIGIT_ONES 1U  //middle
#define DIGIT_UNIT 0U  //right
#define SELECT_DIGIT(digit) (1U << digit)

/* DHT22 peripherals: */
#define DDR_SENSOR   DDRC
#define PORT_SENSOR  PORTC
#define PIN_SENSOR   PINC
#define SENSOR       PINC3

/* DHT22 commands: */
#define SENSOR_sda_out  DDR_SENSOR |= (1 << SENSOR)
#define SENSOR_sda_in   DDR_SENSOR &= ~(1 << SENSOR) // release sda => hi in consequence of pullup
#define SENSOR_sda_low  PORT_SENSOR &= ~(1 << SENSOR)
#define SENSOR_is_hi    PIN_SENSOR & (1 << SENSOR)
#define SENSOR_is_low   !(PIN_SENSOR & (1 << SENSOR))

#define MODE_MEASURE        0U
#define MODE_ANIMATION_1    1U
#define MODE_ANIMATION_2    2U

#define ANIMATION_DELAY_MS 70U

#define ANIMATION_START_DELAY_MS 70U

#define BUTTON_THRESHOLD 50 //software debounce

/* Symbol indexes: */
#define SYM_n           10U
#define SYM_o           11U
#define SYM_E           12U
#define SYM_R           13U
#define SYM_DEG_CELCIUS 14U
#define SYM_P_P         15U
#define SYM_OFF         16U
#define SYM_DASH        17U
#define SYM_I           18U
#define SYM_SEG_A       19U
#define SYM_SEG_B       20U
#define SYM_SEG_C       21U
#define SYM_SEG_D       22U
#define SYM_SEG_E       23U
#define SYM_SEG_F       24U
#define SYM_SEG_AB      25U
#define SYM_SEG_BCD     26U
#define SYM_SEG_CD      27U
#define SYM_SEG_DE      28U
#define SYM_SEG_DEF     29U
#define SYM_SEG_AEF     30U
#define SYM_SEG_AF      31U

/*
 7-Segment Layout:

     A
  F     B
     G  
  E     C
     D    P

 Pin       7  6  5  4  3  2  1  0
 Segment   A  F  B  E  D  C  G  P
*/
static uint8_t g_au8Symbols[32U] =
{
/* 00 */ 0b11111100U, //0 (ABCDEF)
/* 01 */ 0b00100100U, //1 (BC)
/* 02 */ 0b10111010U, //2 (ABDEG)
/* 03 */ 0b10101110U, //3 (ABCDG)
/* 04 */ 0b01100110U, //4 (BCFG)
/* 05 */ 0b11001110U, //5 (ACDFG)
/* 06 */ 0b11011110U, //6 (ACDEFG)
/* 07 */ 0b10100100U, //7 (ABC)
/* 08 */ 0b11111110U, //8 (ABCDEFG)
/* 09 */ 0b11101110U, //9 (ABCDFG)
/* 10 */ 0b00010110U, //n (CEG)      SYM_n
/* 11 */ 0b00011110U, //o (CDEG)     SYM_o
/* 12 */ 0b11011010U, //E (ADEFG)    SYM_E
/* 13 */ 0b00010010U, //r (EG)       SYM_r
/* 14 */ 0b10101101U, //degC (ABCDP) SYM_DEG_CELCIUS
/* 15 */ 0b11110011U, //P. (ABEFGP)  SYM_P_P
/* 16 */ 0b00000000U, //OFF          SYM_OFF
/* 17 */ 0b00000010U, //- (G)        SYM_DASH
/* 18 */ 0b01010000U, //I (EF)       SYM_I
/* 19 */ 0b10000000U, //SegA         SYM_SEG_A
/* 20 */ 0b00100000U, //SegB         SYM_SEG_B
/* 21 */ 0b00000100U, //SegC         SYM_SEG_C
/* 22 */ 0b00001000U, //SegD         SYM_SEG_D
/* 23 */ 0b00010000U, //SegE         SYM_SEG_E
/* 24 */ 0b01000000U, //SegF         SYM_SEG_F
/* 25 */ 0b10100000U, //SegAB        SYM_SEG_AB
/* 26 */ 0b00101100U, //SegBCD       SYM_SEG_BCD
/* 27 */ 0b00001100U, //SegCD        SYM_SEG_CD
/* 28 */ 0b00011000U, //SegDE        SYM_SEG_DE
/* 29 */ 0b01011000U, //SegDEF       SYM_SEG_DEF
/* 30 */ 0b11010000U, //SegAEF       SYM_SEG_AEF
/* 31 */ 0b11000000U  //SegAF        SYM_SEG_AF
};

static uint8_t g_u8ButtonCountTop = 0U;           //upper button counter
static uint8_t g_u8ButtonCountBot = 0U;           //lower button counter
static uint8_t g_u8Mode = MODE_MEASURE;      //Current display mode


uint16_t g_u16Humidity = 0U;
uint16_t g_u16Temperature = 0U;

uint8_t g_u8ISRDigitSelect = 0U;
uint8_t g_au8Digits[3U] =
{
    SYM_OFF, //unit
    SYM_OFF, //ones
    SYM_OFF  //tens
};

void s_vInit( void );
void s_vSetValue( uint8_t u8Value, uint8_t u8Unit );
void s_vSetDisplayDigits( uint8_t u8Tens, uint8_t u8Ones, uint8_t u8Unit );

void s_vReadButtons( void );
void s_vShowAnim( uint8_t u8Select );

uint8_t s_u8ReadSensor( void );

/************************************************************************/
/* Timer1 ISR - show values on display                                  */
/************************************************************************/
ISR ( TIMER1_COMPA_vect )
{
    PORTB = 0;
    PORTD = 0;
    _delay_us(2);
    PORTB = SELECT_DIGIT(g_u8ISRDigitSelect);
    PORTD = g_au8Symbols[g_au8Digits[g_u8ISRDigitSelect]];
    g_u8ISRDigitSelect++;
    if (g_u8ISRDigitSelect > 2U)
    {
        g_u8ISRDigitSelect = 0U;
    }
    
    /* Read and evaluate button status */
    s_vReadButtons();
}

/************************************************************************/
/* main()                                                               */
/************************************************************************/
int main(void)
{
    uint8_t u8ErrorCode = 0U;
    uint8_t u8Loop = 0U;

    s_vInit();
    
    s_vSetDisplayDigits( SYM_OFF, SYM_OFF, SYM_OFF );
    _delay_ms(10);
    
    s_vSetDisplayDigits( SYM_SEG_A, SYM_OFF, SYM_OFF );
    _delay_ms(300);
    s_vSetDisplayDigits( SYM_SEG_A, SYM_SEG_A, SYM_OFF );
    _delay_ms(300);
    s_vSetDisplayDigits( SYM_SEG_A, SYM_SEG_A, SYM_SEG_A );
    _delay_ms(300);
    
    while ( u8Loop < 5U )
    {
        s_vSetDisplayDigits( SYM_OFF, SYM_SEG_A, SYM_SEG_AB );
        _delay_ms(ANIMATION_START_DELAY_MS);
        s_vSetDisplayDigits( SYM_OFF, SYM_OFF, 7U );
        _delay_ms(ANIMATION_START_DELAY_MS);
        s_vSetDisplayDigits( SYM_OFF, SYM_OFF, SYM_SEG_BCD );
        _delay_ms(ANIMATION_START_DELAY_MS);
        s_vSetDisplayDigits( SYM_OFF, SYM_SEG_D, SYM_SEG_CD );
        _delay_ms(ANIMATION_START_DELAY_MS);
        s_vSetDisplayDigits( SYM_SEG_D, SYM_SEG_D, SYM_SEG_D );
        _delay_ms(ANIMATION_START_DELAY_MS);
        s_vSetDisplayDigits( SYM_SEG_DE, SYM_SEG_D, SYM_OFF );
        _delay_ms(ANIMATION_START_DELAY_MS);
        s_vSetDisplayDigits( SYM_SEG_DEF, SYM_OFF, SYM_OFF );
        _delay_ms(ANIMATION_START_DELAY_MS);
        s_vSetDisplayDigits( SYM_SEG_AEF, SYM_OFF, SYM_OFF );
        _delay_ms(ANIMATION_START_DELAY_MS);
        s_vSetDisplayDigits( SYM_SEG_AF, SYM_SEG_A, SYM_OFF );
        _delay_ms(ANIMATION_START_DELAY_MS);
        s_vSetDisplayDigits( SYM_SEG_A, SYM_SEG_A, SYM_SEG_A );
        _delay_ms(ANIMATION_START_DELAY_MS);
        u8Loop++;
    }
    
    /* Set default value: */
    //s_vSetDisplayDigits( SYM_DASH, SYM_DASH, SYM_DASH );
    
    /* wait 3 seconds for humity sensor */
    //_delay_ms(3000);
    
    /* Set default value: */
    s_vSetDisplayDigits( SYM_OFF, SYM_OFF, SYM_OFF );
    _delay_ms(600);

    while ( 1 )
    {
        switch ( g_u8Mode )
        {
            case MODE_MEASURE:
                if ( SENSOR_is_hi )
                {
                    SENSOR_sda_out;
                    SENSOR_sda_low;
                    _delay_ms(20);
                    u8ErrorCode = s_u8ReadSensor();
                    if ( 0U == u8ErrorCode )
                    {
                        s_vSetValue( g_u16Humidity / 10, SYM_P_P );
                        //vSetDisplayValues( g_u16Temperature / 10, SYM_DEG_CELCIUS );
                    }
                    else
                    {
                        s_vSetDisplayDigits( SYM_E, u8ErrorCode, SYM_OFF );
                    }
                }
                if ( g_u8Mode == MODE_MEASURE )
                {
                    _delay_ms(500);
                }
                break;
            case MODE_ANIMATION_1:
                s_vShowAnim(g_u8Mode);
                g_u8Mode = MODE_MEASURE;
                _delay_ms(200);
                break;
            case MODE_ANIMATION_2:
                s_vShowAnim(g_u8Mode);
                g_u8Mode = MODE_MEASURE;
                _delay_ms(200);
                break;
            default:
                break;
        } //end switch

       // _delay_ms(3000); //wait 3 seconds for new measurement
    } //end while(1)

    return 0;
}

/************************************************************************/
/* Initialize inputs and outputs                                        */
/************************************************************************/
void s_vInit( void )
{
    /* Port D - Pins 0-7: Outputs */
    DDRD = 0b11111111U;
    
    /* Port B - Pins 0-2: Outputs */
    DDRB = 0b00000111U;
    
    /* Port C - Pins 4-5: Inputs with internal Pull-up */
    PORTC = 0b00110000U;
    
    /* Sensor init: */
    DDR_SENSOR &= ~(1 << SENSOR);   // define as input
    PORT_SENSOR &= ~(1 << SENSOR);  // disable pullup
    
    /* 16-bit TIMER1 in CTC mode
     * prescaler = 8
     * 20 MHz / 8 = 2.5 MHz
     * Compare value = 2500 => 1 ms IRQ
     */
    TCCR1A = 0U;
    TCCR1B = (1<<WGM12) | (1<<CS11);
    OCR1A = 2500U;
    TIMSK1 |= (1<<OCIE1A);
    sei();
    
    return; //void
}

/************************************************************************/
/* Set new values to be shown on display                                */
/************************************************************************/
void s_vSetValue( uint8_t u8Value, uint8_t u8Unit )
{
    uint8_t u8Tmp = u8Value / 10U;
    s_vSetDisplayDigits(u8Tmp, u8Value - (u8Tmp * 10U), u8Unit);

    return; //void
}

/************************************************************************/
/* Set display digits individually                                      */
/************************************************************************/
void s_vSetDisplayDigits( uint8_t u8Tens, uint8_t u8Ones, uint8_t u8Unit )
{
    g_au8Digits[DIGIT_TENS] = u8Tens;
    g_au8Digits[DIGIT_ONES] = u8Ones;
    g_au8Digits[DIGIT_UNIT] = u8Unit;
    
    return; //void
}

/************************************************************************/
/* Read button status                                                   */
/************************************************************************/
void s_vReadButtons( void )
{
    if ( !(PINC & (1<<PINC4)) ) //if button '+' pressed
    {
        g_u8ButtonCountTop++;
    }
    else
    {
        g_u8ButtonCountTop = 0U; //reset button counter
    }
    
    if ( !(PINC & (1<<PINC5)) ) //if button '-' pressed
    {
        g_u8ButtonCountBot++;
    }
    else
    {
        g_u8ButtonCountBot = 0U; //reset button counter
    }
    
    if ( g_u8ButtonCountTop > BUTTON_THRESHOLD )
    {
        g_u8ButtonCountTop = 0U; //reset top counter
        g_u8Mode =  MODE_ANIMATION_1;
    }
    else if ( g_u8ButtonCountBot > BUTTON_THRESHOLD )
    {
        g_u8ButtonCountBot = 0U; //reset bottom counter
        g_u8Mode =  MODE_ANIMATION_2;
    }

    return; //void
}
/************************************************************************/
/*                                                                      */
/************************************************************************/
void s_vShowAnim( uint8_t u8Select )
{
    s_vSetDisplayDigits( SYM_OFF, SYM_OFF, SYM_OFF );
    _delay_ms(ANIMATION_DELAY_MS);
    switch ( u8Select )
    {
        case MODE_ANIMATION_1: //fade from left to right and from right to left
            s_vSetDisplayDigits( SYM_I, SYM_OFF, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( SYM_E, SYM_OFF, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, SYM_OFF, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            
            s_vSetDisplayDigits( 8U, SYM_I, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, SYM_E, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, 8U, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            
            s_vSetDisplayDigits( 8U, 8U, 1U );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, 8U, 3U );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, 8U, 8U );
            _delay_ms(ANIMATION_DELAY_MS);
            
            s_vSetDisplayDigits( 8U, 8U, 8U );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, 8U, 3U );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, 8U, 1U );
            _delay_ms(ANIMATION_DELAY_MS);
            
            s_vSetDisplayDigits( 8U, 8U, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, SYM_E, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, SYM_I, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            
            s_vSetDisplayDigits( 8U, SYM_OFF, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( SYM_E, SYM_OFF, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( SYM_I, SYM_OFF, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            break;
        case MODE_ANIMATION_2: //fade from left to right and clear
            s_vSetDisplayDigits( SYM_I, SYM_OFF, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( SYM_E, SYM_OFF, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, SYM_OFF, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            
            s_vSetDisplayDigits( 8U, SYM_I, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, SYM_E, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, 8U, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            
            s_vSetDisplayDigits( 8U, 8U, 1U );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, 8U, 3U );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 8U, 8U, 8U );
            _delay_ms(ANIMATION_DELAY_MS);
            
            s_vSetDisplayDigits( 3U, 8U, 8U );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( 1U, 8U, 8U );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( SYM_OFF, 8U, 8U );
            _delay_ms(ANIMATION_DELAY_MS);
            
            s_vSetDisplayDigits( SYM_OFF, 3U, 8U );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( SYM_OFF, 1U, 8U );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( SYM_OFF, SYM_OFF, 8U );
            _delay_ms(ANIMATION_DELAY_MS);
            
            s_vSetDisplayDigits( SYM_OFF, SYM_OFF, SYM_E );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( SYM_OFF, SYM_OFF, SYM_I );
            _delay_ms(ANIMATION_DELAY_MS);
            s_vSetDisplayDigits( SYM_OFF, SYM_OFF, SYM_OFF );
            _delay_ms(ANIMATION_DELAY_MS);
            break;
        default:
            break;
    } //end switch
    s_vSetDisplayDigits( SYM_OFF, SYM_OFF, SYM_OFF );
    _delay_ms(ANIMATION_DELAY_MS);
    
    return; //void
}

/************************************************************************/
/* Read humidity and temperature from DHT22                             */
/************************************************************************/
uint8_t s_u8ReadSensor( void )
{
    uint8_t timeout = 200;
    
    SENSOR_sda_in;

    // Bus master has released time min: 20us, typ: 30us, max: 200us
    while ( SENSOR_is_hi )
    {
        _delay_us(1);
        if ( !timeout-- )
        {
            return 2;
        }
    }

    // AM2302 response signal min: 75us typ:80us max:85us
    timeout = 85;
    while(SENSOR_is_low)
    {
        _delay_us(1);
        if (!timeout--)
        {
            return 3;
        }
    }  // response to low time

    timeout = 85;
    while(SENSOR_is_hi)
    {
        _delay_us(1);
        if (!timeout--)
        {
            return 4;
        }
    }  // response to high time


    /*
     *            time in us: min typ max
     *    signal 0 high time: 22  26  30     (bit=0)
     *    signal 1 high time: 68  70  75     (bit=1)
     *  signal 0,1 down time: 48  50  55
     */

    uint8_t sensor_data[5]={0};

    for(uint8_t i = 0; i < 5; i++)
    {
        uint8_t sensor_byte = 0;
    
        // get 8 bits from sensor
        for(uint8_t j = 1; j <= 8; j++)
        {
            // wait for sensor response
            timeout = 55;
            while(SENSOR_is_low)
            {
                _delay_us(1);

                // if timeout == 0 => sensor do not response
                if (!timeout--)
                {
                    return 5;
                }
            }

            // wait 30 us to check if bit is logical "1" or "0"
            _delay_us(30);
            sensor_byte <<= 1; // add new lower bit

            // If sda ist high after 30 us then bit is logical "1" else it was a logical "0"
            // For a logical "1" sda have to be low after 75 us.
            if (SENSOR_is_hi)
            {
                sensor_byte |= 1; // add logical "1"
                timeout = 45;  // 30us - 75us = 45us

                while(SENSOR_is_hi)
                {
                    _delay_us(1);
                
                    if (!timeout--)
                    {
                        return 6;
                    }
                }
            }
        }

        sensor_data[i] = sensor_byte;
    }

    // checksum
    if ( ((sensor_data[0] + sensor_data[1] + sensor_data[2] + sensor_data[3]) & 0xff ) != sensor_data[4])
    {
        // debug output
        //printf("%b %b %b %b %b %b" CR, sensor_data[0], sensor_data[1], sensor_data[2], sensor_data[3], sensor_data[4], ((sensor_data[0]+sensor_data[1]+sensor_data[2]+sensor_data[3]) & 0xff ));
        return 7;
    }

    g_u16Humidity = (sensor_data[0] << 8) + sensor_data[1];
    g_u16Temperature = (sensor_data[2] << 8) + sensor_data[3];

    return 0;
}