#include "stm32l1xx.h"
#include "PLL/inc/stm32l1xx_gpio.h"
#include "PLL/inc/stm32l1xx_usart.h"
#include "PLL/inc/stm32l1xx_rcc.h"

#define SKIP_ROM 0xCC
#define CONVERT 0x44
#define READ_TEMP 0xBE

#define DS_PORT GPIOA    
#define DS_PIN GPIO_Pin_5

#define ResetDQ() GPIO_WriteBit(DS_PORT, DS_PIN, Bit_RESET)
#define SetDQ() GPIO_WriteBit(DS_PORT, DS_PIN, Bit_SET)
#define GetDQ() GPIO_ReadInputDataBit(DS_PORT,DS_PIN)

void delay_1ms(uint32_t ms)
{
        volatile uint32_t nCount;
        RCC_ClocksTypeDef RCC_Clocks;
        RCC_GetClocksFreq (&RCC_Clocks);

        nCount=(RCC_Clocks.HCLK_Frequency/10000)*ms;
        for (; nCount!=0; nCount--);
}

void delay_1us(uint32_t us)
{
        SysTick->LOAD=us*9;
    SysTick->CTRL|=0x01;
    while(!(SysTick->CTRL&(1<<16)));
    SysTick->CTRL=0x00000000;
    SysTick->VAL=0x00000000;  
}

void GPIO_init()
{
      RCC_AHBPeriphClockCmd(RCC_AHBENR_GPIOAEN, ENABLE);
      //GPIOA->BSRRL = GPIO_BSRR_BS_5;  
      //GPIOA->BSRRH = GPIO_BSRR_BS_5;    
}
void Init_ds18b20(void)    
{
    SetDQ();
    delay_1us(30);    
    ResetDQ();    
    delay_1us(470);      
    SetDQ();      
    delay_1us(30);    
    while(!GetDQ());    
    delay_1us(450);
    SetDQ();    
}


void DS18B20WriteByte( unsigned char  Dat)
{
    uint8_t i;
    for(i=8;i>0;i--)
    {
        ResetDQ();
        delay_1us(5);

        if(Dat&0x01)    
        SetDQ();
        else
        ResetDQ();

        delay_1us(65);
        SetDQ();
        delay_1us(2);
        Dat>>=1;
    }
}

unsigned char  DS18B20ReadByte(void)
{
     unsigned char  i,Dat;
    SetDQ();
    delay_1us(5);
    for(i=0;i<8;i++)
    {
        Dat>>=1;
        ResetDQ();
        delay_1us(5);
        SetDQ();
        delay_1us(5);

        if(GetDQ())
            Dat|=0x80;
        else
            Dat&=0x7f;
        delay_1us(65);
        SetDQ();
    }
    return Dat;
}

unsigned char  readtemperature(void)
{
     unsigned char  a,b;
    Init_ds18b20();
    DS18B20WriteByte(SKIP_ROM);
    DS18B20WriteByte(CONVERT);
    delay_1ms(750);    

    Init_ds18b20();
    DS18B20WriteByte(SKIP_ROM);
    DS18B20WriteByte(READ_TEMP);    

    a=DS18B20ReadByte();    
    b=DS18B20ReadByte();

    b<<=4;
    b+=(a&=0xf0)>>4;

    return b;
}

volatile int temp[8];

int main()
{
   GPIO_init();
  
  volatile uint8_t value=readtemperature();
}