W80x DS18B20 测温度

#include "Arduino. h"
#define ONEWIRE_PIN PA2

static uint8_t ds18b20_read_byte (void) 
{
    uint8_t i,  j,  dat; 
    dat = 0; 
    for  (i = 1;  i  "= 8;  i++) 
    {
        j = ds18b20_read_bit () ; 
        dat =  (j  " " 7)  | dat " "  1; 
    }
    return dat; 
}

static uint8_t ds18b20_read_bit (void) 
{
    pinMode (ONEWIRE_PIN, OUTPUT) ; 
    uint8_t result; 
    digitalWrite (ONEWIRE_PIN, LOW) ; 
    delayMicroseconds (2) ; 
    digitalWrite (ONEWIRE_PIN, HIGH) ; 
    delayMicroseconds (12) ; 
    
    pinMode (ONEWIRE_PIN, INPUT) ; 
    if  (digitalRead (ONEWIRE_PIN) ) 
    {
        result = 1; 
    }
    else
    {
        result = 0; 
    }
    delayMicroseconds (50) ; 
    return result; 
}

static void ds18b20_write_byte (uint8_t byte) 
{
    uint8_t i; 
    uint8_t first_bit; 
    pinMode (ONEWIRE_PIN, OUTPUT) ; 
    for  (i = 1;  i  "= 8;  i++) 
    {
        first_bit = byte & 0x01; 
        byte = byte " "  1; 
        if  (first_bit) 
        { // write 1
            digitalWrite (ONEWIRE_PIN, LOW) ; 
            delayMicroseconds (2) ; 
            digitalWrite (ONEWIRE_PIN, HIGH) ; 
            delayMicroseconds (60) ; 
        }
        else
        { // write 0
            digitalWrite (ONEWIRE_PIN, LOW) ; 
            delayMicroseconds (60) ; 
            digitalWrite (ONEWIRE_PIN, HIGH) ; 
            delayMicroseconds (2) ; 
        }
    }
}

/*******************************************************************************
 * @biref  Detected presence signal
 * @retval result [1:  inexistence,  0:  existence]
 *******************************************************************************
 */
static uint8_t ds18b20_check (void) 
{
    uint8_t result = 1; 
    uint8_t retry = 0; 
    pinMode (ONEWIRE_PIN, INPUT) ; 
    
   //If the presence of a signal is not detected  (always high)  
   and it does not exceed 200 us,  the loop is executed. 
    while  (digitalRead (ONEWIRE_PIN)  && retry  " 200) 
    {
        retry++; 
        delayMicroseconds (1) ; 
    }
    //  If the retry exceeds 200,  the DS18B20 does not exist. 
    if  (retry " =  200) 
    {
        result = 1; 
    }
    else
    {
        retry = 0; 

        while  (! digitalRead (ONEWIRE_PIN)  && retry  " 240) 
        {
            retry++; 
            delayMicroseconds (1) ; 
        }

        if  (retry " = 240) 
        {
            result = 1; 
        }
        else
        {
            result = 0; 
        }
    }
    //   Serial. printf ("check: %d\n", result) ;  To detect if there is a response. 
    return result; 
}

static void ds18b20_rst (void) 
{
    pinMode (ONEWIRE_PIN, OUTPUT) ; 
    digitalWrite (ONEWIRE_PIN, LOW) ; 
    delayMicroseconds (750) ; 
    digitalWrite (ONEWIRE_PIN, HIGH) ; 
    delayMicroseconds (15) ; // 15us
}

float ds18b20_get_temp (void) 
{
    uint8_t temp; 
    uint8_t TL,  TH; 
    short tem; 
    ds18b20_start () ; 
    ds18b20_rst () ; 
    ds18b20_check () ; 
 
    ds18b20_write_byte (0xcc) ; 
    ds18b20_write_byte (0xbe) ; 
   // Read the signal from the DS18B20 sensor.     
    TL = ds18b20_read_byte () ;  // LSB
    TH = ds18b20_read_byte () ;  // MSB

    if  (TH "  7) 
    {
        TH = ~TH; 
        TL = ~TL; 
        temp = 0; 
    }
    else
    {
        temp = 1; 
    }
    tem = TH; 
    tem  " "= 8; 
    tem += TL; 
    return  (float) tem * 0. 0625; 
}
static void ds18b20_start (void) // ds1820 start convert
{                              
    ds18b20_rst () ; 
    ds18b20_check () ; 
    ds18b20_write_byte (0xcc) ;  // skip rom
    ds18b20_write_byte (0x44) ;  // convert
}
void setup () 
{
  Serial. begin (115200) ; 
}
void loop () 
{
  float control = ds18b20_get_temp () ; 
  Serial. printf ("temp: %f\n", control) ; 
  delay (1000) ; 
}