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1 // Matt Johnston 2012 |
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2 // Based on ds18x20.c by Martin Thomas, in turn based on code by |
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3 // Peter // Dannegger and others. |
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4 // |
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5 #include <stdio.h> |
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6 #include <avr/pgmspace.h> |
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7 |
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8 #include "ds18x20.h" |
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9 #include "onewire.h" |
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10 #include "crc8.h" |
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11 |
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12 #include "simple_ds18b20.h" |
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13 |
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14 uint8_t |
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15 simple_ds18b20_start_meas(uint8_t id[]) |
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16 { |
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17 uint8_t ret; |
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18 |
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19 ow_reset(); |
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20 if( ow_input_pin_state() ) { // only send if bus is "idle" = high |
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21 ow_command_with_parasite_enable(DS18X20_CONVERT_T, id); |
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22 ret = DS18X20_OK; |
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23 } |
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24 else { |
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25 ret = DS18X20_START_FAIL; |
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26 } |
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27 |
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28 return ret; |
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29 } |
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30 |
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31 static uint8_t |
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32 read_scratchpad( uint8_t id[], uint8_t sp[], uint8_t n ) |
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33 { |
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34 uint8_t i; |
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35 uint8_t ret; |
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36 |
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37 ow_command( DS18X20_READ, id ); |
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38 for ( i = 0; i < n; i++ ) { |
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39 sp[i] = ow_byte_rd(); |
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40 } |
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41 if ( crc8( &sp[0], DS18X20_SP_SIZE ) ) { |
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42 ret = DS18X20_ERROR_CRC; |
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43 } else { |
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44 ret = DS18X20_OK; |
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45 } |
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46 |
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47 return ret; |
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48 } |
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49 |
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50 static int16_t |
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51 ds18b20_raw_to_decicelsius( uint8_t sp[] ) |
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52 { |
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53 uint16_t measure; |
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54 uint8_t negative; |
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55 int16_t decicelsius; |
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56 uint16_t fract; |
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57 |
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58 measure = sp[0] | (sp[1] << 8); |
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59 //measure = 0xFF5E; // test -10.125 |
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60 //measure = 0xFE6F; // test -25.0625 |
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61 |
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62 // check for negative |
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63 if ( measure & 0x8000 ) { |
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64 negative = 1; // mark negative |
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65 measure ^= 0xffff; // convert to positive => (twos complement)++ |
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66 measure++; |
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67 } |
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68 else { |
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69 negative = 0; |
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70 } |
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71 |
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72 // clear undefined bits for DS18B20 != 12bit resolution |
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73 switch( sp[DS18B20_CONF_REG] & DS18B20_RES_MASK ) { |
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74 case DS18B20_9_BIT: |
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75 measure &= ~(DS18B20_9_BIT_UNDF); |
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76 break; |
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77 case DS18B20_10_BIT: |
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78 measure &= ~(DS18B20_10_BIT_UNDF); |
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79 break; |
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80 case DS18B20_11_BIT: |
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81 measure &= ~(DS18B20_11_BIT_UNDF); |
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82 break; |
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83 default: |
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84 // 12 bit - all bits valid |
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85 break; |
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86 } |
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87 |
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88 decicelsius = (measure >> 4); |
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89 decicelsius *= 10; |
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90 |
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91 // decicelsius += ((measure & 0x000F) * 640 + 512) / 1024; |
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92 // 625/1000 = 640/1024 |
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93 fract = ( measure & 0x000F ) * 640; |
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94 if ( !negative ) { |
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95 fract += 512; |
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96 } |
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97 fract /= 1024; |
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98 decicelsius += fract; |
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99 |
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100 if ( negative ) { |
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101 decicelsius = -decicelsius; |
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102 } |
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103 |
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104 if ( /* decicelsius == 850 || */ decicelsius < -550 || decicelsius > 1250 ) { |
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105 return DS18X20_INVALID_DECICELSIUS; |
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106 } else { |
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107 return decicelsius; |
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108 } |
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109 } |
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110 |
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111 uint8_t |
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112 simple_ds18b20_read_decicelsius( uint8_t id[], int16_t *decicelsius ) |
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113 { |
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114 uint8_t sp[DS18X20_SP_SIZE]; |
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115 uint8_t ret; |
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116 |
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117 if (id) |
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118 { |
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119 ow_reset(); |
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120 } |
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121 ret = read_scratchpad( id, sp, DS18X20_SP_SIZE ); |
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122 if ( ret == DS18X20_OK ) { |
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123 *decicelsius = ds18b20_raw_to_decicelsius( sp ); |
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124 } |
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125 return ret; |
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126 } |
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127 |
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128 static void |
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129 printhex_nibble(const unsigned char b) |
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130 { |
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131 unsigned char c = b & 0x0f; |
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132 if ( c > 9 ) { |
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133 c += 'A'-10; |
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134 } |
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135 else { |
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136 c += '0'; |
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137 } |
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138 putchar(c); |
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139 } |
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140 |
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141 void |
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142 printhex_byte( const unsigned char b ) |
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143 { |
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144 printhex_nibble( b >> 4 ); |
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145 printhex_nibble( b ); |
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146 } |
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147 |
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148 void |
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149 printhex(uint8_t *id, uint8_t n) |
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150 { |
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151 for (uint8_t i = 0; i < n; i++) |
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152 { |
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153 if (i > 0) |
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154 { |
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155 putchar(' '); |
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156 } |
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157 printhex_byte(id[i]); |
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158 } |
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159 } |
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160 |
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161 |
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162 uint8_t |
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163 simple_ds18b20_read_all() |
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164 { |
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165 uint8_t id[OW_ROMCODE_SIZE]; |
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166 for( uint8_t diff = OW_SEARCH_FIRST; diff != OW_LAST_DEVICE; ) |
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167 { |
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168 diff = ow_rom_search( diff, &id[0] ); |
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169 |
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170 if( diff == OW_PRESENCE_ERR ) { |
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171 printf_P( PSTR("No Sensor found\r") ); |
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172 return OW_PRESENCE_ERR; // <--- early exit! |
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173 } |
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174 |
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175 if( diff == OW_DATA_ERR ) { |
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176 printf_P( PSTR("Bus Error\r") ); |
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177 return OW_DATA_ERR; // <--- early exit! |
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178 } |
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179 |
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180 int16_t decicelsius; |
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181 uint8_t ret = simple_ds18b20_read_decicelsius(NULL, &decicelsius); |
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182 if (ret != DS18X20_OK) |
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183 { |
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184 printf_P(PSTR("Failed reading\r")); |
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185 return OW_DATA_ERR; |
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186 } |
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187 |
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188 printf_P(PSTR("DS18B20 %d: "), diff); |
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189 if (crc8(id, OW_ROMCODE_SIZE)) |
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190 { |
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191 printf_P(PSTR("CRC fail")); |
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192 } |
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193 printhex(id, OW_ROMCODE_SIZE); |
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194 printf_P(PSTR(" %d.%d ºC\n"), decicelsius/10, decicelsius % 10); |
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195 } |
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196 printf_P(PSTR("Done sensors\n")); |
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197 return DS18X20_OK; |
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198 } |
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199 |
