Zoltan Hudak / DS1820

Dallas' DS1820 family temperature sensor. For more details see [https://developer.mbed.org/users/hudakz/code/DS1820/wiki/Homepage]

Dependencies:   OneWire

Dependents:   BLE_nRF24L01 frdm_serialfgmp gather_sensor_data UltiSaverController ... more

Some programs using the DS1820 library:

Import programDS1820_Hello

Simple DS1820 sensor demo showing how to use the DS1820 library [https://developer.mbed.org/users/hudakz/code/DS1820/]

Last commit 20 Jul 2020 by Zoltan Hudak

Import programBLE_nRF24L01

Bluetooth Low Energy (BLE) beacon with nRF24L01(+). Data is received and displayed by Android device (Android app source code is attached).

Last commit 26 Jan 2016 by Zoltan Hudak

Examples of use:

Single DS1820 sensor

/*
 * Single DS1820 sensor GPIO driven
 *
 * Note: Don't forget to connect a 4.7k Ohm resistor 
 *       between the DS1820's data pin and the +3.3V pin
 *
 *           ----------------
 *          |                |   ----------------------->  +3.3V
 *          |   MBED BOARD   |  |
 *          |                |  |   ------
 *          |          +3.3V |--o--| 4.7k |-------
 *          |                |      ------        |
 *          |                |                    |
 *          |                |                    |
 *          |                |                    |
 *          |                |                    |
 *          |           GPIO |--------------------o----->  1-wire bus/line
 *          |                |
 *          |                |
 *          |            GND |-------------------------->  GND
 *          |                |
 *           ----------------
 *
 */
 
#include "mbed.h"
#include "DS1820.h"
 
Serial serial(USBTX, USBRX);
 
int main() {
    DS1820  ds1820(D8);    // substitute D8 with actual mbed pin name connected to the DS1820 data pin    
                             
    if(ds1820.begin()) {
        while(1) {
            ds1820.startConversion();     // start temperature conversion
            ThisThread::sleep_for(1000);  // let DS1820 complete the temperature conversion
            serial.printf("temp = %3.1f\r\n", ds1820.read());     // read temperature
        }
    } else
        serial.printf("No DS1820 sensor found!\r\n");
}

Single DS1820 sensor. Data integrity is assured by performing CRC.

/*
 * Single DS1820 sensor GPIO driven + performing CRC
 *
 * Note: Don't forget to connect a 4.7k Ohm resistor 
 *       between the DS1820's data pin and the +3.3V pin
 *
 *           ----------------
 *          |                |   ----------------------->  +3.3V
 *          |   MBED BOARD   |  |
 *          |                |  |   ------
 *          |          +3.3V |--o--| 4.7k |-------
 *          |                |      ------        |
 *          |                |                    |
 *          |                |                    |
 *          |                |                    |
 *          |                |                    |
 *          |           GPIO |--------------------o----->  1-wire bus/line
 *          |                |
 *          |                |
 *          |            GND |-------------------------->  GND
 *          |                |
 *           ----------------
 *
 */
 
#include "mbed.h"
#include "DS1820.h"
 
Serial serial(USBTX, USBRX);
 
int main() {
    DS1820  ds1820(D8);    // substitute D8 with actual mbed pin name connected to the DS1820 data pin   
    float   temp = 0;
    int     error = 0; 
                             
    if(ds1820.begin()) {
        while(1) {
            ds1820.startConversion();    // start temperature conversion
            ThisThread::sleep_for(1000); // let DS1820 complete the temperature conversion
            error = ds1820.read(temp);   // read temperature from DS1820 and perform cyclic redundancy check (CRC)
            switch(error) {
            case 0:    // no errors -> 'temp' contains the value of measured temperature
                serial.printf("temp = %3.1f\r\n", temp);
                break;
            case 1:    // no sensor present -> 'temp' is not updated
                serial.printf("no sensor present\n\r");
                break;
            case 2:    // CRC error -> 'temp' is not updated
                serial.printf("CRC error\r\n");
            } 
        }
    } else
        serial.printf("No DS1820 sensor found!\r\n");
}

Several DS1820 sensors connected to the same 1-wire bus.

/*
 * Multiple sensors GPIO driven
 *
 * Note: Don't forget to connect a 4.7k Ohm resistor 
 *       between the 1-wire bus data line and the +3.3V rail
 *
 *           ----------------
 *          |                |   ----------------------->  +3.3V
 *          |   MBED BOARD   |  |
 *          |                |  |   ------
 *          |          +3.3V |--o--| 4.7k |-------
 *          |                |      ------        |
 *          |                |                    |
 *          |                |                    |
 *          |                |                    |
 *          |                |                    |
 *          |           GPIO |--------------------o----->  1-wire bus/line
 *          |                |
 *          |                |
 *          |            GND |-------------------------->  GND
 *          |                |
 *           ----------------
 *
 */

#include "mbed.h"
#include "DS1820.h"

#define     MAX_SENSOSRS   32   // max number of DS1820 sensors to be connected to the 1-wire bus (max 256)

DS1820*     ds1820[MAX_SENSOSRS];
Serial      pc(USBTX, USBRX);
DigitalOut  led(LED1);
OneWire     oneWire(D8);        // substitute D8 with the actual pin name connected to the 1-wire bus
int         sensorsFound = 0;   // counts the actually found DS1820 sensors

int main()
{
    pc.printf("\r\n--Starting--\r\n");
    
    //Enumerate (i.e. detect) DS1820 sensors on the 1-wire bus
    for (sensorsFound = 0; sensorsFound < MAX_SENSOSRS; sensorsFound++) {
        ds1820[sensorsFound] = new DS1820(&oneWire);
        if (!ds1820[sensorsFound]->begin()) {
            delete ds1820[sensorsFound];
            break;
        }
    }

    switch (sensorsFound) {
        case 0:
            pc.printf("No DS1820 sensor found!\r\n");
            return -1;

        case 1:
            pc.printf("One DS1820 sensor found.\r\n");
            break;

        default:
            pc.printf("Found %d DS1820 sensors.\r\n", sensorsFound);
    }

    while (1) {
        pc.printf("----------------\r\n");
        for (int i = 0; i < sensorsFound; i++)
            ds1820[i]->startConversion();        // start temperature conversion from analog to digital
        ThisThread::sleep_for(1000);             // let DS1820 sensors complete the temperature conversion
        for (int i = 0; i < sensorsFound; i++) {
            if (ds1820[i]->isPresent())
                pc.printf("temp[%d] = %3.1f%cC\r\n", i, ds1820[i]->read(), 176); // read temperature
        }
    }
}

Several DS1820 sensors connected to the same 1-wire bus. UART is used to implement the bus

/*
 * Multiple sensors UART driven:
 * 
 *          UART is driving the 1-Wire Bus Master according to Maxim Integrated application note
 *
 *          https://www.maximintegrated.com/en/design/technical-documents/tutorials/2/214.html
 *
 *          In addition to the 4.7k Ohm resistor between the 1-wire data bus/line and the +3.3V pin,
 *          a 470 Ohm resistor shall be tied to the UART's tx and rx pin. UART's rx pin is then used
 *          as 1-wire data bus/line.
 *
 *           ----------------
 *          |                |   ----------------------->  +3.3V
 *          |   MBED BOARD   |  |
 *          |                |  |   ------
 *          |          +3.3V |--o--| 4.7k |-------
 *          |                |      ------        |
 *          |                |      ------        |
 *          |        UART TX |-----|  470 |---    |
 *          |                |      ------    |   |
 *          |                |                |   |
 *          |        UART RX |----------------o---o----->  1-wire bus/line
 *          |                |
 *          |                |
 *          |            GND |-------------------------->  GND
 *          |                |
 *           ----------------
 *
 */
#include "mbed.h"
#include "DS1820.h"

#define MAX_SENSOSRS    32      // max number of DS1820 sensors to be connected to the 1-wire bus (max 256)
DS1820*     ds1820[MAX_SENSOSRS];
DigitalOut  led(LED1);
OneWire     oneWire(p9, p10);       // LPC1768 (UART Tx pin, UART Rx pin)
//OneWire     oneWire(PA_0, PA_1);    // NUCLE0-F446RE (UART Tx pin, UART Rx pin)
int         sensorsFound = 0;       // counts the actually found DS1820 sensors

/**
 * @brief
 * @note
 * @param
 * @retval
 */
int main()
{
    printf("\r\n--Starting--\r\n");

    //Enumerate (i.e. detect) DS1820 sensors on the 1-wire bus
    for (sensorsFound = 0; sensorsFound < MAX_SENSOSRS; sensorsFound++) {
        ds1820[sensorsFound] = new DS1820(&oneWire);
        if (!ds1820[sensorsFound]->begin()) {
            delete ds1820[sensorsFound];
            break;
        }
    }

    switch (sensorsFound) {
        case 0:
            printf("No DS1820 sensor found!\r\n");
            return -1;

        case 1:
            printf("One DS1820 sensor found.\r\n");
            break;

        default:
            printf("Found %d DS1820 sensors.\r\n", sensorsFound);
    }

    while (1) {
        led = !led;

        printf("----------------\r\n");
        for (int i = 0; i < sensorsFound; i++)
            ds1820[i]->startConversion();   // start temperature conversion from analog to digital
        #if (MBED_MAJOR_VERSION > 5)
            ThisThread::sleep_for(1s);
        #else
            wait(1);
        #endif


        for (int i = 0; i < sensorsFound; i++) {
            if (ds1820[i]->isPresent())
                printf("temp[%d] = %3.1f%cC\r\n", i, ds1820[i]->read(), 176);   // read temperature
        }
    }
}

Diff: DS1820.cpp

Revision:
24:d683d826dccd
Parent:
23:74a4ff420541
--- a/DS1820.cpp	Mon Jul 20 08:09:58 2020 +0000
+++ b/DS1820.cpp	Mon Dec 28 21:15:27 2020 +0000
@@ -4,54 +4,54 @@
  * available at <http://developer.mbed.org/users/hudakz/code/OneWire/>
  *
  * Example of use:
- * 
+ *
  * Single sensor.
  *
  * #include "mbed.h"
  * #include "DS1820.h"
- * 
+ *
  * Serial      pc(USBTX, USBRX);
  * DigitalOut  led(LED1);
  * OneWire     oneWire(D8);    // substitute D8 with actual mbed pin name connected 1-wire bus
  * float       temp = 0;
  * int         result = 0;
- * 
+ *
  * int main()
  * {
  *     pc.printf("\r\n--Starting--\r\n");
  *     if (ds1820.begin()) {
  *         while (1) {
  *             ds1820.startConversion();   // start temperature conversion from analog to digital
- *             ThisThread::sleep_for(1000);// let DS1820 complete the temperature conversion
- *             result = ds1820.read(temp); // read temperature from DS1820 and perform cyclic redundancy check (CRC)
+ *             ThisThread::sleep_for(1000ms);// let DS1820 complete the temperature conversion
+ *             result = ds1820.read(temp);   // read temperature from DS1820 and perform cyclic redundancy check (CRC)
  *             switch (result) {
- *                 case 0:                 // no errors -> 'temp' contains the value of measured temperature
+ *                 case 0:                   // no errors -> 'temp' contains the value of measured temperature
  *                     pc.printf("temp = %3.1f%cC\r\n", temp, 176);
  *                     break;
- * 
- *                 case 1:                 // no sensor present -> 'temp' is not updated
+ *
+ *                 case 1:                   // no sensor present -> 'temp' is not updated
  *                     pc.printf("no sensor present\n\r");
  *                     break;
- * 
- *                 case 2:                 // CRC error -> 'temp' is not updated
+ *
+ *                 case 2:                   // CRC error -> 'temp' is not updated
  *                     pc.printf("CRC error\r\n");
  *             }
- * 
+ *
  *             led = !led;
  *         }
  *     }
  *     else
  *         pc.printf("No DS1820 sensor found!\r\n");
  * }
- * 
- * 
+ *
+ *
  * More sensors connected to the same 1-wire bus.
- * 
+ *
  * #include "mbed.h"
  * #include "DS1820.h"
- * 
+ *
  * #define     SENSORS_COUNT   64      // number of DS1820 sensors to be connected to the 1-wire bus (max 256)
- * 
+ *
  * Serial      pc(USBTX, USBRX);
  * DigitalOut  led(LED1);
  * OneWire     oneWire(D8);            // substitute D8 with actual mbed pin name connected to the DS1820 data pin
@@ -59,10 +59,10 @@
  * int         sensors_found = 0;      // counts the actually found DS1820 sensors
  * float       temp = 0;
  * int         result = 0;
- * 
+ *
  * int main() {
  *     int i = 0;
- *     
+ *
  *     pc.printf("\r\n Starting \r\n");
  *     //Enumerate (i.e. detect) DS1820 sensors on the 1-wire bus
  *     for(i = 0; i < SENSORS_COUNT; i++) {
@@ -72,46 +72,61 @@
  *             break;
  *         }
  *     }
- *     
+ *
  *     sensors_found = i;
- *     
+ *
  *     if (sensors_found == 0) {
  *         pc.printf("No DS1820 sensor found!\r\n");
  *         return -1;
  *     }
  *     else
  *         pc.printf("Found %d sensors.\r\n", sensors_found);
- *     
+ *
  *     while(1) {
  *         pc.printf("-------------------\r\n");
  *         for(i = 0; i < sensors_found; i++)
- *             ds1820[i]->startConversion();   // start temperature conversion from analog to digital       
- *         ThisThread::sleep_for(1000);        // let DS1820s complete the temperature conversion
+ *             ds1820[i]->startConversion();   // start temperature conversion from analog to digital
+ *         ThisThread::sleep_for(1000ms);      // let DS1820s complete the temperature conversion
  *         for(int i = 0; i < sensors_found; i++) {
  *             if(ds1820[i]->isPresent())
  *                 pc.printf("temp[%d] = %3.1f%cC\r\n", i, ds1820[i]->read(), 176);     // read temperature
  *         }
  *     }
  * }
- * 
+ *
  */
- 
 #include "DS1820.h"
 
-#define DEBUG 0
+//#define DEBUG   1
 
 //* Initializing static members
-uint8_t DS1820::lastAddr[8] = {0, 0, 0, 0, 0, 0, 0, 0};
+uint8_t DS1820::    _lastAddr[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
+
 /**
  * @brief   Constructs a generic DS1820 sensor
  * @note    begin() must be called to detect and initialize the actual model
- * @param   pin: Name of data pin
+ * @param   gpioPin: Name of the GPIO pin
  * @retval
  */
-DS1820::DS1820(PinName pin, int sample_point_us /* = 13 */) {
-    oneWire = new OneWire(pin, sample_point_us);
-    present = false;
-    model_s = false;
+DS1820::DS1820(PinName gpioPin, int samplePoint_us /*=13*/ )
+{
+    _oneWire = new OneWire(gpioPin, samplePoint_us);
+    _present = false;
+    _model_s = false;
+}
+
+/**
+ * @brief   Constructs a generic DS1820 sensor
+ * @note    begin() must be called to detect and initialize the actual model
+ * @param   txPin:  UART's Tx pin
+ * @param   rxPin:  UART's Rx pin
+ * @retval
+ */
+DS1820::DS1820(PinName txPin, PinName rxPin)
+{
+    _oneWire = new OneWire(txPin, rxPin);
+    _present = false;
+    _model_s = false;
 }
 
 /**
@@ -120,10 +135,11 @@
  * @param   pin: Name of data pin
  * @retval
  */
-DS1820::DS1820(OneWire* wire) :
-    oneWire(wire) {
-    present = false;
-    model_s = false;
+DS1820::DS1820(OneWire* oneWire) :
+    _oneWire(oneWire)
+{
+    _present = false;
+    _model_s = false;
 }
 
 /**
@@ -133,73 +149,82 @@
  * @retval  true:   if a DS1820 family sensor was detected and initialized
             false:  otherwise
  */
-bool DS1820::begin(void) {
+bool DS1820::begin(void)
+{
 #if DEBUG
     printf("lastAddr =");
-    for(uint8_t i = 0; i < 8; i++) {
+    for (uint8_t i = 0; i < 8; i++) {
         printf(" %x", lastAddr[i]);
     }
+
     printf("\r\n");
 #endif
-    if(!oneWire->search(lastAddr)) {
+    if (!_oneWire->search(_lastAddr))
+    {
 #if DEBUG
         printf("No addresses.\r\n");
 #endif
-        oneWire->reset_search();
-        ThisThread::sleep_for(250);
+        _oneWire->reset_search();
+#if MBED_MAJOR_VERSION == 2
+        wait_ms(250);
+#else
+        ThisThread::sleep_for(250ms);
+#endif
         return false;
     }
-    
+
     for (int i = 0; i < 8; i++)
-        addr[i] = lastAddr[i];
+        _addr[i] = _lastAddr[i];
 
 #if DEBUG
     printf("ROM =");
-    for(uint8_t i = 0; i < 8; i++) {
+    for (uint8_t i = 0; i < 8; i++) {
         printf(" %x", addr[i]);
     }
+
     printf("\r\n");
 #endif
-
-    if(OneWire::crc8(addr, 7) == addr[7]) {
-        present = true;
+    if (OneWire::crc8(_addr, 7) == _addr[7]) {
+        _present = true;
 
         // the first ROM byte indicates which chip
-        switch(addr[0]) {
-        case 0x10:
-            model_s = true;
-#if DEBUG
-            printf("DS18S20 or old DS1820\r\n");
-#endif            
-            break;
+        switch (_addr[0]) {
+            case 0x10:
+                _model_s = true;
+    #if DEBUG
+                printf("DS18S20 or old DS1820\r\n");
+    #endif
+                break;
 
-        case 0x28:
-            model_s = false;
-#if DEBUG
-            printf("DS18B20\r\n");
-#endif            
-            break;
+            case 0x28:
+                _model_s = false;
+    #if DEBUG
+                printf("DS18B20\r\n");
+    #endif
+                break;
 
-        case 0x22:
-            model_s = false;
-#if DEBUG
-            printf("DS1822\r\n");
-#endif            
-            break;
+            case 0x22:
+                _model_s = false;
+    #if DEBUG
+                printf("DS1822\r\n");
+    #endif
+                break;
 
-        default:
-            present = false;
-#if DEBUG
-            printf("Device doesn't belong to the DS1820 family\r\n");
-#endif            
-            return false;
+            default:
+                _present = false;
+    #if DEBUG
+                printf("Device doesn't belong to the DS1820 family\r\n");
+    #endif
+                return false;
         }
+
         return true;
     }
-    else {
-#if DEBUG    
+    else
+    {
+#if DEBUG
         printf("Invalid CRC!\r\n");
-#endif    
+#endif
         return false;
     }
 }
@@ -207,14 +232,15 @@
 /**
  * @brief   Informs about presence of a DS1820 sensor.
  * @note    begin() shall be called before using this function
- *          if a generic DS1820 instance was created by the user. 
+ *          if a generic DS1820 instance was created by the user.
  *          No need to call begin() for a specific DS1820 instance.
  * @param
  * @retval  true:   when a DS1820 sensor is present
  *          false:  otherwise
  */
-bool DS1820::isPresent(void) {
-    return present;
+bool DS1820::isPresent(void)
+{
+    return _present;
 }
 
 /**
@@ -226,27 +252,29 @@
  * @param   res:    Resolution of the temperature-to-digital conversion in bits.
  * @retval
  */
-void DS1820::setResolution(uint8_t res) {
+void DS1820::setResolution(uint8_t res)
+{
     // keep resolution within limits
-    if(res > 12)
+
+    if (res > 12)
         res = 12;
-    if(res < 9)
-        res = 9;      
-    if(model_s)
+    if (res < 9)
+        res = 9;
+    if (_model_s)
         res = 9;
-       
-    oneWire->reset();
-    oneWire->select(addr);
-    oneWire->write_byte(0xBE);            // to read Scratchpad
-    for(uint8_t i = 0; i < 9; i++)  // read Scratchpad bytes
-        data[i] = oneWire->read_byte();   
+
+    _oneWire->reset();
+    _oneWire->select(_addr);
+    _oneWire->write_byte(0xBE);      // to read Scratchpad
+    for (uint8_t i = 0; i < 9; i++) // read Scratchpad bytes
+        _data[i] = _oneWire->read_byte();
 
-    data[4] |= (res - 9) << 5;      // update configuration byte (set resolution)  
-    oneWire->reset();
-    oneWire->select(addr);
-    oneWire->write_byte(0x4E);            // to write into Scratchpad
-    for(uint8_t i = 2; i < 5; i++)  // write three bytes (2nd, 3rd, 4th) into Scratchpad
-        oneWire->write_byte(data[i]);
+    _data[4] |= (res - 9) << 5;      // update configuration byte (set resolution)
+    _oneWire->reset();
+    _oneWire->select(_addr);
+    _oneWire->write_byte(0x4E);      // to write into Scratchpad
+    for (uint8_t i = 2; i < 5; i++) // write three bytes (2nd, 3rd, 4th) into Scratchpad
+        _oneWire->write_byte(_data[i]);
 }
 
 /**
@@ -259,11 +287,12 @@
  * @param
  * @retval
  */
-void DS1820::startConversion(void) {
-    if(present) {
-        oneWire->reset();
-        oneWire->select(addr);
-        oneWire->write_byte(0x44);    //start temperature conversion
+void DS1820::startConversion(void)
+{
+    if (_present) {
+        _oneWire->reset();
+        _oneWire->select(_addr);
+        _oneWire->write_byte(0x44);  //start temperature conversion
     }
 }
 
@@ -273,49 +302,48 @@
  * @param
  * @retval  Floating point temperature value
  */
-float DS1820::read(void) {
-    if(present) {
-        oneWire->reset();
-        oneWire->select(addr);
-        oneWire->write_byte(0xBE);           // to read Scratchpad
-        for(uint8_t i = 0; i < 9; i++)      // reading scratchpad registers
-            data[i] = oneWire->read_byte();
+float DS1820::read(void)
+{
+    if (_present) {
+        _oneWire->reset();
+        _oneWire->select(_addr);
+        _oneWire->write_byte(0xBE);          // to read Scratchpad
+        for (uint8_t i = 0; i < 9; i++)     // reading scratchpad registers
+            _data[i] = _oneWire->read_byte();
 
         // Convert the raw bytes to a 16-bit unsigned value
-        uint16_t*   p_word = reinterpret_cast < uint16_t * > (&data[0]);
+        uint16_t*   p_word = reinterpret_cast < uint16_t * > (&_data[0]);
 
 #if DEBUG
         printf("raw = %#x\r\n", *p_word);
-#endif            
-
-        if(model_s) {
+#endif
+        if (_model_s) {
             *p_word = *p_word << 3;         // 9-bit resolution
-            if(data[7] == 0x10) {
+            if (_data[7] == 0x10) {
 
                 // "count remain" gives full 12-bit resolution
-                *p_word = (*p_word & 0xFFF0) + 12 - data[6];
+                *p_word = (*p_word & 0xFFF0) + 12 - _data[6];
             }
         }
         else {
-            uint8_t cfg = (data[4] & 0x60); // default 12-bit resolution
-            
+            uint8_t cfg = (_data[4] & 0x60); // default 12-bit resolution
+
             // at lower resolution, the low bits are undefined, so let's clear them
-            if(cfg == 0x00)
+            if (cfg == 0x00)
                 *p_word = *p_word &~7;      //  9-bit resolution
             else
-            if(cfg == 0x20)
+            if (cfg == 0x20)
                 *p_word = *p_word &~3;      // 10-bit resolution
             else
-            if(cfg == 0x40)
+            if (cfg == 0x40)
                 *p_word = *p_word &~1;      // 11-bit resolution
-                                               
         }
 
         // Convert the raw bytes to a 16-bit signed fixed point value :
         // 1 sign bit, 7 integer bits, 8 fractional bits (two’s compliment
         // and the LSB of the 16-bit binary number represents 1/256th of a unit).
         *p_word = *p_word << 4;
-        
+
         // Convert to floating point value
         return(toFloat(*p_word));
     }
@@ -335,70 +363,72 @@
  *              1 - sensor not present ('temp' is not updated)
  *              2 - CRC error ('temp' is not updated)
  */
-uint8_t DS1820::read(float& temp) {
-    if(present) {
-        oneWire->reset();
-        oneWire->select(addr);
-        oneWire->write_byte(0xBE);               // to read Scratchpad
-        for(uint8_t i = 0; i < 9; i++)          // reading scratchpad registers
-            data[i] = oneWire->read_byte();
+uint8_t DS1820::read(float& temp)
+{
+    if (_present) {
+        _oneWire->reset();
+        _oneWire->select(_addr);
+        _oneWire->write_byte(0xBE);              // to read Scratchpad
+        for (uint8_t i = 0; i < 9; i++)         // reading scratchpad registers
+            _data[i] = _oneWire->read_byte();
 
-        if(oneWire->crc8(data, 8) != data[8])    // if calculated CRC does not match the stored one
+        if (_oneWire->crc8(_data, 8) != _data[8])  // if calculated CRC does not match the stored one
         {
 #if DEBUG
-            for(uint8_t i = 0; i < 9; i++)
+            for (uint8_t i = 0; i < 9; i++)
                 printf("data[%d]=0x%.2x\r\n", i, data[i]);
-#endif            
+#endif
             return 2;                           // return with CRC error
         }
 
         // Convert the raw bytes to a 16bit unsigned value
-        uint16_t*   p_word = reinterpret_cast < uint16_t * > (&data[0]);
+        uint16_t*   p_word = reinterpret_cast < uint16_t * > (&_data[0]);
 
 #if DEBUG
         printf("raw = %#x\r\n", *p_word);
 #endif
-
-        if(model_s) {
-            *p_word = *p_word << 3;         // 9 bit resolution,  max conversion time = 750ms
-            if(data[7] == 0x10) {
+        if (_model_s) {
+            *p_word = *p_word << 3;             // 9 bit resolution,  max conversion time = 750ms
+            if (_data[7] == 0x10) {
 
                 // "count remain" gives full 12 bit resolution
-                *p_word = (*p_word & 0xFFF0) + 12 - data[6];
+                *p_word = (*p_word & 0xFFF0) + 12 - _data[6];
             }
 
             // Convert the raw bytes to a 16bit signed fixed point value :
             // 1 sign bit, 7 integer bits, 8 fractional bits (two's compliment
             // and the LSB of the 16bit binary number represents 1/256th of a unit).
             *p_word = *p_word << 4;
+
             // Convert to floating point value
             temp = toFloat(*p_word);
-            return 0;   // return with no errors
+            return 0;                           // return with no errors
         }
         else {
-            uint8_t cfg = (data[4] & 0x60); // default 12bit resolution, max conversion time = 750ms
+            uint8_t cfg = (_data[4] & 0x60);     // default 12bit resolution, max conversion time = 750ms
 
             // at lower resolution, the low bits are undefined, so let's clear them
-            if(cfg == 0x00)
-                *p_word = *p_word &~7;      //  9bit resolution, max conversion time = 93.75ms
+            if (cfg == 0x00)
+                *p_word = *p_word &~7;          //  9bit resolution, max conversion time = 93.75ms
             else
-            if(cfg == 0x20)
-                *p_word = *p_word &~3;      // 10bit resolution, max conversion time = 187.5ms
+            if (cfg == 0x20)
+                *p_word = *p_word &~3;          // 10bit resolution, max conversion time = 187.5ms
             else
-            if(cfg == 0x40)
-                *p_word = *p_word &~1;      // 11bit resolution, max conversion time = 375ms
+            if (cfg == 0x40)
+                *p_word = *p_word &~1;          // 11bit resolution, max conversion time = 375ms
 
             // Convert the raw bytes to a 16bit signed fixed point value :
             // 1 sign bit, 7 integer bits, 8 fractional bits (two's complement
             // and the LSB of the 16bit binary number represents 1/256th of a unit).
             *p_word = *p_word << 4;
+
             // Convert to floating point value
             temp = toFloat(*p_word);
-            return 0;   // return with no errors
+            return 0;                           // return with no errors
         }
     }
     else
-        return 1;   // error, sensor is not present
+        return 1;                               // error, sensor is not present
 }
 
 /**
@@ -406,14 +436,14 @@
  * @note    The 16-bit unsigned integer represnts actually
  *          a 16-bit signed fixed point value:
  *          1 sign bit, 7 integer bits, 8 fractional bits (two’s complement
- *          and the LSB of the 16-bit binary number represents 1/256th of a unit).       
+ *          and the LSB of the 16-bit binary number represents 1/256th of a unit).
  * @param   16-bit unsigned integer
  * @retval  Floating point value
  */
-float DS1820::toFloat(uint16_t word) {
-    if(word & 0x8000)
-        return (-float(uint16_t(~word + 1)) / 256.0f);
+float DS1820::toFloat(uint16_t word)
+{
+    if (word & 0x8000)
+        return(-float(uint16_t(~word + 1)) / 256.0f);
     else
-        return (float(word) / 256.0f);
+        return(float(word) / 256.0f);
 }
-