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
        }
    }
}

DS1820.cpp@0:433af64321d5, 2015-03-15 (annotated)

Committer:
hudakz
Date:
Sun Mar 15 14:16:16 2015 +0000
Revision:
0:433af64321d5
Child:
1:e4689408d617
Dallas' DS1820 family temperature sensor

Who changed what in which revision?

UserRevisionLine numberNew contents of line
hudakz 0:433af64321d5 1 #include "DS1820.h"
hudakz 0:433af64321d5 2
hudakz 0:433af64321d5 3 #define DEBUG 1
hudakz 0:433af64321d5 4
hudakz 0:433af64321d5 5 #if DEBUG
hudakz 0:433af64321d5 6 extern Serial serial;
hudakz 0:433af64321d5 7 #endif
hudakz 0:433af64321d5 8
hudakz 0:433af64321d5 9 /**
hudakz 0:433af64321d5 10 * @brief Constructs a generic DS1820 sensor
hudakz 0:433af64321d5 11 * @note begin() must be called to detect and initialize the actual model
hudakz 0:433af64321d5 12 * @param Name of data pin
hudakz 0:433af64321d5 13 * @retval
hudakz 0:433af64321d5 14 */
hudakz 0:433af64321d5 15 DS1820::DS1820(PinName pin) :
hudakz 0:433af64321d5 16 oneWire(pin) {
hudakz 0:433af64321d5 17 present = 0;
hudakz 0:433af64321d5 18 type_s = 0;
hudakz 0:433af64321d5 19 }
hudakz 0:433af64321d5 20
hudakz 0:433af64321d5 21 /**
hudakz 0:433af64321d5 22 * @brief Constructs a specific model
hudakz 0:433af64321d5 23 * @note No need to call begin() to detect and initialize the model
hudakz 0:433af64321d5 24 * @param One character model name: 'S', 's', 'B' or 'b'
hudakz 0:433af64321d5 25 * Name of data pin
hudakz 0:433af64321d5 26 * @retval
hudakz 0:433af64321d5 27 */
hudakz 0:433af64321d5 28 DS1820::DS1820(char model, PinName pin) :
hudakz 0:433af64321d5 29 oneWire(pin) {
hudakz 0:433af64321d5 30 if((model == 'S') or (model == 's')) {
hudakz 0:433af64321d5 31 present = 1;
hudakz 0:433af64321d5 32 type_s = 1;
hudakz 0:433af64321d5 33 }
hudakz 0:433af64321d5 34 else if((model == 'B') or (model == 'b')) {
hudakz 0:433af64321d5 35 present = 1;
hudakz 0:433af64321d5 36 type_s = 0;
hudakz 0:433af64321d5 37 }
hudakz 0:433af64321d5 38 else
hudakz 0:433af64321d5 39 present = 0;
hudakz 0:433af64321d5 40 }
hudakz 0:433af64321d5 41
hudakz 0:433af64321d5 42 /**
hudakz 0:433af64321d5 43 * @brief Detects and initializes the actual DS1820 model
hudakz 0:433af64321d5 44 * @note
hudakz 0:433af64321d5 45 * @param
hudakz 0:433af64321d5 46 * @retval true: if a DS1820 family sensor was detected and initialized
hudakz 0:433af64321d5 47 false: otherwise
hudakz 0:433af64321d5 48 */
hudakz 0:433af64321d5 49 bool DS1820::begin(void) {
hudakz 0:433af64321d5 50 oneWire.reset_search();
hudakz 0:433af64321d5 51 wait_ms(250);
hudakz 0:433af64321d5 52 if(!oneWire.search(addr)) {
hudakz 0:433af64321d5 53 #if DEBUG
hudakz 0:433af64321d5 54 serial.printf("No addresses.\r\n");
hudakz 0:433af64321d5 55 #endif
hudakz 0:433af64321d5 56 oneWire.reset_search();
hudakz 0:433af64321d5 57 wait_ms(250);
hudakz 0:433af64321d5 58 return false;
hudakz 0:433af64321d5 59 }
hudakz 0:433af64321d5 60
hudakz 0:433af64321d5 61 #if DEBUG
hudakz 0:433af64321d5 62 serial.printf("ROM =");
hudakz 0:433af64321d5 63 for(uint8_t i = 0; i < 8; i++) {
hudakz 0:433af64321d5 64 serial.printf(" %x", addr[i]);
hudakz 0:433af64321d5 65 }
hudakz 0:433af64321d5 66 serial.printf("\r\n");
hudakz 0:433af64321d5 67 #endif
hudakz 0:433af64321d5 68
hudakz 0:433af64321d5 69 if(OneWire::crc8(addr, 7) == addr[7]) {
hudakz 0:433af64321d5 70 present = 1;
hudakz 0:433af64321d5 71
hudakz 0:433af64321d5 72 // the first ROM byte indicates which chip
hudakz 0:433af64321d5 73 switch(addr[0]) {
hudakz 0:433af64321d5 74 case 0x10:
hudakz 0:433af64321d5 75 type_s = 1;
hudakz 0:433af64321d5 76 #if DEBUG
hudakz 0:433af64321d5 77 serial.printf("DS18S20 or old DS1820\r\n");
hudakz 0:433af64321d5 78 #endif
hudakz 0:433af64321d5 79 break;
hudakz 0:433af64321d5 80
hudakz 0:433af64321d5 81 case 0x28:
hudakz 0:433af64321d5 82 type_s = 0;
hudakz 0:433af64321d5 83 #if DEBUG
hudakz 0:433af64321d5 84 serial.printf("DS18B20\r\n");
hudakz 0:433af64321d5 85 #endif
hudakz 0:433af64321d5 86 break;
hudakz 0:433af64321d5 87
hudakz 0:433af64321d5 88 case 0x22:
hudakz 0:433af64321d5 89 type_s = 0;
hudakz 0:433af64321d5 90 #if DEBUG
hudakz 0:433af64321d5 91 serial.printf("DS1822\r\n");
hudakz 0:433af64321d5 92 #endif
hudakz 0:433af64321d5 93 break;
hudakz 0:433af64321d5 94
hudakz 0:433af64321d5 95 default:
hudakz 0:433af64321d5 96 present = 0;
hudakz 0:433af64321d5 97 #if DEBUG
hudakz 0:433af64321d5 98 serial.printf("Device doesn't belong to the DS1820 family\r\n");
hudakz 0:433af64321d5 99 return false;
hudakz 0:433af64321d5 100 #endif
hudakz 0:433af64321d5 101 }
hudakz 0:433af64321d5 102 return true;
hudakz 0:433af64321d5 103 }
hudakz 0:433af64321d5 104 #if DEBUG
hudakz 0:433af64321d5 105 else {
hudakz 0:433af64321d5 106 serial.printf("Invalid CRC!\r\n");
hudakz 0:433af64321d5 107 return false;
hudakz 0:433af64321d5 108 }
hudakz 0:433af64321d5 109 #endif
hudakz 0:433af64321d5 110 }
hudakz 0:433af64321d5 111
hudakz 0:433af64321d5 112 /**
hudakz 0:433af64321d5 113 * @brief Starts temperature conversion
hudakz 0:433af64321d5 114 * @note The time to complete the converion depends on the selected resolusion
hudakz 0:433af64321d5 115 * @param
hudakz 0:433af64321d5 116 * @retval
hudakz 0:433af64321d5 117 */
hudakz 0:433af64321d5 118 void DS1820::startConversion(void) {
hudakz 0:433af64321d5 119 if(present) {
hudakz 0:433af64321d5 120 oneWire.reset();
hudakz 0:433af64321d5 121
hudakz 0:433af64321d5 122 //oneWire.select(addr);
hudakz 0:433af64321d5 123 oneWire.skip();
hudakz 0:433af64321d5 124 oneWire.write(0x44); //start conversion
hudakz 0:433af64321d5 125 }
hudakz 0:433af64321d5 126 }
hudakz 0:433af64321d5 127
hudakz 0:433af64321d5 128 /**
hudakz 0:433af64321d5 129 * @brief Reads temperature from the chip's scratchpad
hudakz 0:433af64321d5 130 * @note
hudakz 0:433af64321d5 131 * @param
hudakz 0:433af64321d5 132 * @retval Floating point temperature value
hudakz 0:433af64321d5 133 */
hudakz 0:433af64321d5 134 float DS1820::read(void) {
hudakz 0:433af64321d5 135 if(present) {
hudakz 0:433af64321d5 136 oneWire.reset();
hudakz 0:433af64321d5 137 oneWire.skip();
hudakz 0:433af64321d5 138 oneWire.write(0xBE); // to read Scratchpad
hudakz 0:433af64321d5 139 for(uint8_t i = 0; i < 9; i++)
hudakz 0:433af64321d5 140 data[i] = oneWire.read();
hudakz 0:433af64321d5 141
hudakz 0:433af64321d5 142 // Convert the raw bytes to a 16bit signed fixed point value :
hudakz 0:433af64321d5 143 // 1 sign bit, 7 integer bits, 8 fractional bits (two’s compliment
hudakz 0:433af64321d5 144 // ie. the LSB of the 16bit binary number represents 1/256th of a unit).
hudakz 0:433af64321d5 145
hudakz 0:433af64321d5 146 uint16_t* p_word = reinterpret_cast < uint16_t * > (&data[0]);
hudakz 0:433af64321d5 147
hudakz 0:433af64321d5 148 #if DEBUG
hudakz 0:433af64321d5 149 serial.printf("raw = %#x\r\n", *p_word);
hudakz 0:433af64321d5 150 #endif
hudakz 0:433af64321d5 151
hudakz 0:433af64321d5 152
hudakz 0:433af64321d5 153 if(type_s) {
hudakz 0:433af64321d5 154 *p_word = *p_word << 3; // default 9 bit resolution
hudakz 0:433af64321d5 155 if(data[7] == 0x10) {
hudakz 0:433af64321d5 156
hudakz 0:433af64321d5 157 // "count remain" gives full 12 bit resolution
hudakz 0:433af64321d5 158 *p_word = (*p_word & 0xFFF0) + 12 - data[6];
hudakz 0:433af64321d5 159 }
hudakz 0:433af64321d5 160
hudakz 0:433af64321d5 161 *p_word = *p_word << 4;
hudakz 0:433af64321d5 162 return(toFloat(*p_word));
hudakz 0:433af64321d5 163 }
hudakz 0:433af64321d5 164 else {
hudakz 0:433af64321d5 165 uint8_t cfg = (data[4] & 0x60);
hudakz 0:433af64321d5 166 // at lower res, the low bits are undefined, so let's zero them
hudakz 0:433af64321d5 167
hudakz 0:433af64321d5 168 if(cfg == 0x00)
hudakz 0:433af64321d5 169 *p_word = *p_word &~7; // 9 bit resolution, 93.75 ms
hudakz 0:433af64321d5 170 else
hudakz 0:433af64321d5 171 if(cfg == 0x20)
hudakz 0:433af64321d5 172 *p_word = *p_word &~3; // 10 bit res, 187.5 ms
hudakz 0:433af64321d5 173 else
hudakz 0:433af64321d5 174 if(cfg == 0x40)
hudakz 0:433af64321d5 175 *p_word = *p_word &~1; // 11 bit res, 375 ms
hudakz 0:433af64321d5 176 *p_word = *p_word << 4; // default is 12 bit resolution
hudakz 0:433af64321d5 177 return(toFloat(*p_word));
hudakz 0:433af64321d5 178 }
hudakz 0:433af64321d5 179 }
hudakz 0:433af64321d5 180 else
hudakz 0:433af64321d5 181 return 0;
hudakz 0:433af64321d5 182 }
hudakz 0:433af64321d5 183
hudakz 0:433af64321d5 184 /**
hudakz 0:433af64321d5 185 * @brief Converts a 16bit signed fixed point value to float
hudakz 0:433af64321d5 186 * @note The 16bit unsigned integer represnts actually
hudakz 0:433af64321d5 187 * a 16bit signed fixed point value:
hudakz 0:433af64321d5 188 * 1 sign bit, 7 integer bits, 8 fractional bits
hudakz 0:433af64321d5 189 * (two’s compliment ie. the LSB of the 16bit binary number
hudakz 0:433af64321d5 190 * represents 1/256th of a unit).
hudakz 0:433af64321d5 191 * @param 16bit unsigned integer
hudakz 0:433af64321d5 192 * @retval Floating point temperature value
hudakz 0:433af64321d5 193 */
hudakz 0:433af64321d5 194 float DS1820::toFloat(uint16_t word) {
hudakz 0:433af64321d5 195 //word = word << 4;
hudakz 0:433af64321d5 196 if(word & 0x8000)
hudakz 0:433af64321d5 197 return (-float(uint16_t(~word + 1)) / 256.0f);
hudakz 0:433af64321d5 198 else
hudakz 0:433af64321d5 199 return (float(word) / 256.0f);
hudakz 0:433af64321d5 200 }
hudakz 0:433af64321d5 201