STM8L controls the temperature sensor DS18B20

#define DS18B20_GPIO_PORT (GPIOC)

#define DS18B20_GPIO_PIN (GPIO_Pin_2)

#define DS18B20_PIN_SET_OUT() GPIO_Init(DS18B20_GPIO_PORT, (GPIO_Pin_TypeDef)DS18B20_GPIO_PIN, GPIO_Mode_Out_PP_High_Fast)

#define DS18B20_PIN_SET_IN() GPIO_Init(DS18B20_GPIO_PORT, (GPIO_Pin_TypeDef)DS18B20_GPIO_PIN, GPIO_Mode_In_PU_No_IT)

#define DS18B20_WR1() GPIO_SetBits(DS18B20_GPIO_PORT, (GPIO_Pin_TypeDef)DS18B20_GPIO_PIN)

#define DS18B20_WR0() GPIO_ResetBits(DS18B20_GPIO_PORT, (GPIO_Pin_TypeDef)DS18B20_GPIO_PIN)

#define R_DS18B20() GPIO_ReadInputDataBit(DS18B20_GPIO_PORT, (GPIO_Pin_TypeDef)DS18B20_GPIO_PIN)

/* Private macro -------------------------------------------------------------*/

#define READ_ROM 0x33 //Read serial number

#define SKIP_ROM 0xCC //Skip ROM

#define MATCH_ROM 0x55 //Match ROM

#define CONVERT_TEM 0x44 //Conversion temperature

#define READ_RAM ​​0xBE //Read temporary register

#define WRITE_RAM 0x4E //Write register

/* Private variables ---------------------------------------------------------*/

/* Private function prototypes -----------------------------------------------*/

void _delay_us(uint16_t nCount)

{

    nCount *= 3; 

    while(--nCount);

}

/**

  * @brief _delay_ms

  * @param nCount

  * @retval None

  */

void _delay_ms(uint16_t nCount)

{

    while(nCount--)

    {

        _delay_us(1000);

    }

}

/* Private functions ---------------------------------------------------------*/

/* Public functions ----------------------------------------------------------*/

void Alarm_for_No_DS18B20(void)

{

    //If DS18B20 is not found on the single bus, an alarm will be triggered. This action will be handled according to the specific application.

}

//---------------------------------------------------------------------

unsigned char DS18B20_Start(void) //Reset ds18b20 chip

{

    unsigned char i,succ=0xff;

    DS18B20_PIN_SET_OUT(); //Set to output port

    DS18B20_WR0(); //The bus generates a falling edge, initialization starts

    for(i=0; i<30; i++)_delay_us(25); //The bus keeps low level between 480 - 960 microseconds; i<20; (25us)

    DS18B20_WR1(); //Pull the bus high

    DS18B20_PIN_SET_IN(); //Set to input, the host releases the bus and prepares to receive the response pulse of DS18B20

    i=0;

    while(R_DS18B20()) //Wait for DS18B20 to send a response pulse

    {

        _delay_us(5); //5

        if(++i>12) //DS18B20 waits for 15-60us after detecting the rising edge of the bus

        {

            succ=0x00; //If the waiting time is greater than about 60us, report reset failure

            break;

        }

    }

    i=0;

    while(!R_DS18B20()) //DS18B20 sends out existence pulse, lasting 60-240us

    {

        _delay_us(5); //5

        if(++i>48) //If the waiting time is greater than about 240us, report reset failure

        {

            succ=0x00;

            break;

        }

    }

    _delay_us(20);

    return succ;

}

//---------------------------------------------------------------------

void DS18B20_SendU8(unsigned char d8) // write one byte to DS18B20

{

    unsigned char i;

    DS18B20_PIN_SET_OUT(); //Set to output port

    for(i=0; i<8; i++)

    {

        DS18B20_WR0(); //Pull the bus low to start the "write time slice"

        _delay_us(2); // greater than 1 microsecond

        if(d8&0x01)DS18B20_WR1();

        _delay_us (32); //Delay at least 60 microseconds to make the write effective

        _delay_us (30);

        DS18B20_WR1(); //Pull the bus high, release the bus, and prepare to start the next "write time slice"

        d8>>=1;

        _delay_us (1);

    }

    DS18B20_PIN_SET_IN(); //Host releases the bus

}

//---------------------------------------------------------------------

unsigned char DS18B20_ReadU8(void) // read 1 byte from DS18B20

{

    unsigned char i,d8;

    for(i=0; i<8; i++)

    {

        d8>>=1;

        DS18B20_PIN_SET_OUT(); //Set as output port

        DS18B20_WR0(); //Pull the bus low to start reading the "time slice"

        _delay_us(2); // greater than 1 microsecond

        DS18B20_WR1(); //Host releases the bus, and the read is valid within (2~15)us

        DS18B20_PIN_SET_IN(); //Set the pin as input port, ready to read

        _delay_us(2); //Delay 2 us before reading

        if(R_DS18B20())d8|=0x80; //Read bus data within about 15 microseconds from the time the bus is pulled low

        _delay_us(32); //Reading completed after 60us

        _delay_us(30);

        DS18B20_WR1(); //Pull the bus high, the host releases the bus, and prepares to start the next "write time slice"

    }

    DS18B20_PIN_SET_IN(); //Host releases the bus

    return(d8);

}

//------------------------------------------------------------------------------------

void Init_DS18B20(void) //Initialize DS18B20

{

    unsigned char i;

    i=DS18B20_Start(); //Reset

    if(!i) //no DS18B20 is found on the single bus, then an alarm is raised

    {

        Alarm_for_No_DS18B20();

        return;

    }

    DS18B20_SendU8 (SKIP_ROM); //Skip ROM matching

    DS18B20_SendU8 (WRITE_RAM); //Set write mode

    DS18B20_SendU8 (0x64); //Set the upper temperature limit to 100 degrees Celsius

    DS18B20_SendU8 (0x8a); //Set the temperature to -10 degrees Celsius

    DS18B20_SendU8 (0x7f); //12bit (default)

}

//--------------------------------------------------------------------------------------

unsigned int Read_DS18B20(void) //Read and calculate the temperature to be output

{

    unsigned char i;

    unsigned char tl;

    unsigned int th;

    i=DS18B20_Start(); //Reset

    if(!i) //no DS18B20 is found on the single bus, then an alarm is raised

    {

        Alarm_for_No_DS18B20();

        return 0;

    }

    _delay_ms(1);

    DS18B20_SendU8(SKIP_ROM); //Send the command to skip the serial number detection

    DS18B20_SendU8(CONVERT_TEM); // Command Ds18b20 to start converting temperature

    i=0;

    _delay_ms(1);

    while(!R_DS18B20()) //When temperature conversion is in progress, the host will receive 0 when reading the bus, and 1 when the conversion is completed

    {

        _delay_ms(3);

        if(++i>250) break; //The maximum conversion time is 750ms

    }

    DS18B20_Start(); //Initialization

    _delay_ms(1);

    DS18B20_SendU8(SKIP_ROM); //Send the command to skip the serial number detection

    DS18B20_SendU8(READ_RAM); //Send command to read temperature data

    tl=DS18B20_ReadU8(); //Read the lower 8 bits of temperature data first

    th=DS18B20_ReadU8()<<8; //Read the high 8-bit temperature data again

    return (th|tl)*10>>4; //The temperature is magnified 10 times,*0.0625=1/16=>>4

}