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

NO LONGER USED

/* 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) 

/* DS18B20 peripherals: */
#define DS18B20_PORT PORTC
#define DS18B20_DDR  DDRC
#define DS18B20_PIN  PINC
#define DS18B20_DQ   PINC3

/* DS18B20 commands: */
#define DS18B20_CMD_CONVERTTEMP     0x44U
#define DS18B20_CMD_RSCRATCHPAD     0xBEU
#define DS18B20_CMD_WSCRATCHPAD     0x4EU
#define DS18B20_CMD_CPYSCRATCHPAD   0x48U
#define DS18B20_CMD_RECEEPROM       0xB8U
#define DS18B20_CMD_RPWRSUPPLY      0xB4U
#define DS18B20_CMD_SEARCHROM       0xF0U
#define DS18B20_CMD_READROM         0x33U
#define DS18B20_CMD_MATCHROM        0x55U
#define DS18B20_CMD_SKIPROM         0xCCU
#define DS18B20_CMD_ALARMSEARCH     0xECU

/* 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

/*
 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[18U] =
{
/* 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
};

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

void vInit( void );
void vSetValue( uint8_t u8Value, uint8_t u8Unit );
void vSetDisplayDigits( uint8_t u8Tens, uint8_t u8Ones, uint8_t u8Unit );
uint8_t u8DS18B20_Reset( void );
void vDS18B20_WriteByte( uint8_t u8Byte );
void vDS18B20_WriteBit( uint8_t u8Bit );
uint8_t u8DS18B20_ReadByte( void );
uint8_t u8DS18B20_ReadBit( 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;
    }
}

/************************************************************************/
/* main()                                                               */
/************************************************************************/
int main(void)
{
    uint8_t u8TempLo, u8TempHi;
    float f32Temperature;
    
    /* Init I/O: */
    vInit();
    
    /* Set default value: */
    vSetDisplayDigits( SYM_DASH, SYM_DASH, SYM_DASH );
    
    /* wait 3 seconds for DS18B20 sensor */
    _delay_ms(2400);
    
    while (1)
    {
        (void) u8DS18B20_Reset();
        vDS18B20_WriteByte( DS18B20_CMD_SKIPROM ); 
        vDS18B20_WriteByte( DS18B20_CMD_CONVERTTEMP ); 
        while ( !u8DS18B20_ReadBit() );
        (void) u8DS18B20_Reset();
        vDS18B20_WriteByte( DS18B20_CMD_SKIPROM );
        vDS18B20_WriteByte( DS18B20_CMD_RSCRATCHPAD );
        u8TempLo = u8DS18B20_ReadByte();
        u8TempHi = u8DS18B20_ReadByte();
        f32Temperature = ((u8TempHi << 8) + u8TempLo) * 0.0625;
        vSetValue( (uint8_t) f32Temperature, SYM_DEG_CELCIUS );
        _delay_ms(500);
    } //end while(1)
}

/************************************************************************/
/* Initialize inputs and outputs                                        */
/************************************************************************/
void vInit( void )
{
    /* Port D - Pins 0-7: Outputs */
    DDRD = 0b11111111U;
    
    /* Port B - Pins 0-2: Outputs */
    DDRB = 0b00000111U;
    
    /* 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 vSetValue( uint8_t u8Value, uint8_t u8Unit )
{
    uint8_t u8Tmp = u8Value / 10U;
    vSetDisplayDigits(u8Tmp, u8Value - (u8Tmp * 10U), u8Unit);

    return; //void
}

/************************************************************************/
/* Set display digits individually                                      */
/************************************************************************/
void 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
}

/************************************************************************/
/* Reset DS18B20 (960 us)                                               */
/************************************************************************/
uint8_t u8DS18B20_Reset( void )
{
    uint8_t u8Status;

    //low for 480 us
    DS18B20_PORT &= ~ (1<<DS18B20_DQ);  //low
    DS18B20_DDR |= (1<<DS18B20_DQ);     //output
    _delay_us(480);

    //release line and wait for 60 us
    DS18B20_DDR &= ~(1<<DS18B20_DQ);    //input
    _delay_us(60);

    //get value and wait 420 us
    u8Status = (DS18B20_PIN & (1<<DS18B20_DQ));
    _delay_us(420);

    //return the read value: 0=okay, 1=error
    return u8Status;
}

/************************************************************************/
/* Write byte to DS18B20 (8 * 61 us = 488 us)                           */
/************************************************************************/
void vDS18B20_WriteByte( uint8_t u8Byte )
{
    uint8_t u8Bits = 8U;
    
    while ( u8Bits-- )
    {
        vDS18B20_WriteBit( u8Byte & 1U );
        u8Byte >>= 1U;
    }
    
    return; //void
}


/************************************************************************/
/* Write single bit to DS18B20 (61 us)                                  */
/************************************************************************/
void vDS18B20_WriteBit( uint8_t u8Bit )
{
    //low for 1 us
    DS18B20_PORT &= ~ (1U<<DS18B20_DQ); //low
    DS18B20_DDR |= (1U<<DS18B20_DQ); //output
    _delay_us(1);

    //if we want to write 1, release the line (if not will keep low)
    if (1U == u8Bit )
    {
        DS18B20_DDR &= ~(1<<DS18B20_DQ); //input
    }

    //wait 60 us and release the line
    _delay_us(60);
    DS18B20_DDR &= ~(1<<DS18B20_DQ); //input
    
    return; //void
}

/************************************************************************/
/* Read byte from DS18B20 (8 * 60 us = 480 us)                          */
/************************************************************************/
uint8_t u8DS18B20_ReadByte( void )
{
    uint8_t u8Bits = 8U;
    uint8_t n = 0U;
    while ( u8Bits-- )
    {
        n >>= 1U;
        n |= (u8DS18B20_ReadBit()<<7U);
    }

    return n;
}

/************************************************************************/
/* Read single bit from DS18B20 (60 us)                                 */
/************************************************************************/
uint8_t u8DS18B20_ReadBit( void )
{
    uint8_t u8Bit = 0U;

    //low for 1 us
    DS18B20_PORT &= ~ (1U<<DS18B20_DQ); //low
    DS18B20_DDR |= (1U<<DS18B20_DQ); //output
    _delay_us(1);

    //release line and wait for 14 us
    DS18B20_DDR &= ~(1U<<DS18B20_DQ); //input
    _delay_us(14);

    //read the value
    if ( DS18B20_PIN & (1U<<DS18B20_DQ) )
    {
        u8Bit = 1U;
    }
    
    //wait 45 us and return read value
    _delay_us(45);
    
    return u8Bit;
}