1 | #include <OneWire.h>
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2 |
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3 | // OneWire DS18S20, DS18B20, DS1822 Temperature Example
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4 | //
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5 | // http://www.pjrc.com/teensy/td_libs_OneWire.html
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6 | //
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7 | // The DallasTemperature library can do all this work for you!
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8 | // http://milesburton.com/Dallas_Temperature_Control_Library
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9 |
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10 | OneWire ds(10); // on pin 10 (a 4.7K resistor is necessary)
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11 |
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12 | void setup(void) {
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13 | Serial.begin(9600);
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14 | }
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15 |
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16 | void loop(void) {
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17 | byte i;
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18 | byte present = 0;
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19 | byte type_s;
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20 | byte data[12];
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21 | byte addr[8];
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22 | float celsius, fahrenheit;
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23 |
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24 | if ( !ds.search(addr)) {
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25 | Serial.println("No more addresses.");
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26 | Serial.println();
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27 | ds.reset_search();
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28 | delay(250);
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29 | return;
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30 | }
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31 |
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32 | Serial.print("ROM =");
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33 | for( i = 0; i < 8; i++) {
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34 | Serial.write(' ');
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35 | Serial.print(addr[i], HEX);
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36 | }
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37 |
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38 | if (OneWire::crc8(addr, 7) != addr[7]) {
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39 | Serial.println("CRC is not valid!");
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40 | return;
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41 | }
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42 | Serial.println();
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43 |
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44 | // the first ROM byte indicates which chip
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45 | switch (addr[0]) {
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46 | case 0x10:
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47 | Serial.println(" Chip = DS18S20"); // or old DS1820
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48 | type_s = 1;
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49 | break;
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50 | case 0x28:
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51 | Serial.println(" Chip = DS18B20");
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52 | type_s = 0;
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53 | break;
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54 | case 0x22:
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55 | Serial.println(" Chip = DS1822");
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56 | type_s = 0;
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57 | break;
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58 | default:
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59 | Serial.println("Device is not a DS18x20 family device.");
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60 | return;
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61 | }
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62 |
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63 | ds.reset();
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64 | ds.select(addr);
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65 | ds.write(0x44, 1); // start conversion, with parasite power on at the end
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66 |
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67 | delay(1000); // maybe 750ms is enough, maybe not
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68 | // we might do a ds.depower() here, but the reset will take care of it.
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69 |
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70 | present = ds.reset();
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71 | ds.select(addr);
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72 | ds.write(0xBE); // Read Scratchpad
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73 |
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74 | Serial.print(" Data = ");
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75 | Serial.print(present, HEX);
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76 | Serial.print(" ");
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77 | for ( i = 0; i < 9; i++) { // we need 9 bytes
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78 | data[i] = ds.read();
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79 | Serial.print(data[i], HEX);
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80 | Serial.print(" ");
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81 | }
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82 | Serial.print(" CRC=");
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83 | Serial.print(OneWire::crc8(data, 8), HEX);
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84 | Serial.println();
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85 |
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86 | // Convert the data to actual temperature
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87 | // because the result is a 16 bit signed integer, it should
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88 | // be stored to an "int16_t" type, which is always 16 bits
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89 | // even when compiled on a 32 bit processor.
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90 | int16_t raw = (data[1] << 8) | data[0];
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91 | if (type_s) {
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92 | raw = raw << 3; // 9 bit resolution default
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93 | if (data[7] == 0x10) {
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94 | // "count remain" gives full 12 bit resolution
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95 | raw = (raw & 0xFFF0) + 12 - data[6];
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96 | }
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97 | } else {
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98 | byte cfg = (data[4] & 0x60);
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99 | // at lower res, the low bits are undefined, so let's zero them
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100 | if (cfg == 0x00) raw = raw & ~7; // 9 bit resolution, 93.75 ms
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101 | else if (cfg == 0x20) raw = raw & ~3; // 10 bit res, 187.5 ms
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102 | else if (cfg == 0x40) raw = raw & ~1; // 11 bit res, 375 ms
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103 | //// default is 12 bit resolution, 750 ms conversion time
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104 | }
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105 | celsius = (float)raw / 16.0;
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106 | fahrenheit = celsius * 1.8 + 32.0;
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107 | Serial.print(" Temperature = ");
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108 | Serial.print(celsius);
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109 | Serial.print(" Celsius, ");
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110 | Serial.print(fahrenheit);
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111 | Serial.println(" Fahrenheit");
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112 | }
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