1 | //----------------------------------------
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2 | // Reset DS18S20
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3 | //----------------------------------------
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4 | uint8_t ds1820_reset(uint8_t used_pin)
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5 | {
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6 | uint8_t err=100;
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7 | DS1820_DDR |= 1<<used_pin; // define as ouput
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8 | DS1820_PORT &= ~(1<<used_pin); //Pull low
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9 | _delay_us(480); ; // 480 us
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10 | DS1820_DDR &= ~(1<<used_pin); // define as input
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11 | DS1820_PORT |= 1<<used_pin; //Pullup on
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12 | _delay_us(80); // 66 us
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13 | err = (DS1820_PIN & (1<<used_pin)) >> used_pin; // no presence detect --> err=1 otherwise err=0
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14 | _delay_us(400); // 240 us
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15 | if( (DS1820_PIN & (1<<used_pin)) == 0 ){ // short circuit --> err=2
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16 | err = 2;
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17 | }
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18 | return err;
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19 | }
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20 | //-----------------------------------------
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21 | // Write one bit to DS18S20
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22 | //-----------------------------------------
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23 | void ds1820_wr_bit(uint8_t wrbit,uint8_t used_pin)
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24 | {
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25 | if (wrbit ==0) {
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26 | DS1820_DDR |= 1<<used_pin; // define as ouput
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27 | DS1820_PORT &= ~(1<<used_pin); //Pull low
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28 | _delay_us(60);
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29 | DS1820_DDR &= ~(1<<used_pin); // define as input
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30 | DS1820_PORT |= 1<<used_pin; //Pullup on
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31 | _delay_us(4);
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32 | }
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33 | if (wrbit ==1) {
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34 | DS1820_DDR |= 1<<used_pin; // define as ouput
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35 | DS1820_PORT &= ~(1<<used_pin); //Pull low
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36 | _delay_us(10);
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37 | DS1820_DDR &= ~(1<<used_pin); // define as input
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38 | DS1820_PORT |= 1<<used_pin; //Pullup on
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39 | _delay_us(54);
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40 | }
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41 | }
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42 | //-----------------------------------------
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43 | // Read one bit from DS18S20
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44 | //-----------------------------------------
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45 | uint8_t ds1820_re_bit(uint8_t used_pin)
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46 | {
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47 | uint8_t rebit;
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48 | DS1820_DDR |= 1<<used_pin; // define as ouput
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49 | DS1820_PORT &= ~(1<<used_pin); //Pull low
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50 | _delay_us(2);
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51 | DS1820_DDR &= ~(1<<used_pin); // define as input
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52 | DS1820_PORT |= 1<<used_pin; //Pullup on
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53 | _delay_us(10);
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54 | rebit = (DS1820_PIN & (1<<used_pin)) >> used_pin; //Read bit
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55 | _delay_us(48);
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56 | return rebit;
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57 | }
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58 | //-----------------------------------------
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59 | // Read 1 byte from DS18S20
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60 | //-----------------------------------------
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61 | uint8_t ds1820_re_byte(uint8_t used_pin)
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62 | {
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63 | uint8_t rebyte =0x00;
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64 | uint8_t rebit;
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65 | uint8_t i;
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66 |
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67 | for (i=0;i<8;i++)
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68 | {
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69 | rebit=ds1820_re_bit(used_pin);
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70 | _delay_us(2); //be on the save side
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71 | if (rebit==1){
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72 | rebyte|=(1<<i);
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73 | }
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74 | }
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75 | return(rebyte);
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76 | }
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77 | //-----------------------------------------
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78 | // Write 1 byte to DS18S20
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79 | //-----------------------------------------
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80 | void ds1820_wr_byte(uint8_t wrbyte,uint8_t used_pin)
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81 | {
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82 | uint8_t i;
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83 | for (i=0; i<8; i++) // writes byte, one bit at a time
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84 | {
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85 | ds1820_wr_bit((wrbyte & 0b00000001),used_pin);
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86 | wrbyte = wrbyte >> 1;
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87 | }
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88 | _delay_us(5);
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89 | }
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90 | //-----------------------------------------
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91 | // Read temperature
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92 | //-----------------------------------------
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93 | float ds1820_read_temp(uint8_t used_pin)
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94 | {
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95 | uint8_t error;
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96 | uint16_t i=0;
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97 | uint8_t scratchpad[9];
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98 | float temp=0;
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99 |
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100 | scratchpad[0]=0;
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101 | scratchpad[1]=0;
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102 | scratchpad[2]=0;
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103 | scratchpad[3]=0;
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104 | scratchpad[4]=0;
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105 | scratchpad[5]=0;
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106 | scratchpad[6]=0;
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107 | scratchpad[7]=0;
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108 | scratchpad[8]=0;
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109 |
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110 | error=ds1820_reset(used_pin);
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111 | //1. Reset
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112 | if (error==0){
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113 | ds1820_wr_byte(0xCC,used_pin); //2. skip ROM
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114 | ds1820_wr_byte(0x44,used_pin); //3. ask for temperature conversion
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115 |
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116 | for (i = 0;i < 760;i++){ //4. wait until conversion is finished
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117 | _delay_ms(1);
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118 | }
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119 |
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120 | // while (ds1820_re_byte(used_pin)!=0xFF){ //4. wait until conversion is finished
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121 | // _delay_us(10);
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122 | // i++;
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123 | // }
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124 |
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125 | error=ds1820_reset(used_pin); //5. Reset
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126 | ds1820_wr_byte(0xCC,used_pin); //6. skip ROM
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127 | ds1820_wr_byte(0xBE,used_pin); //7. Read entire scratchpad 9 bytes
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128 |
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129 | for (i=0; i<9; i++) //8. Get scratchpad byte by byte
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130 | {
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131 | scratchpad[i]=ds1820_re_byte(used_pin); //9. read one DS18S20 byte
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132 | }
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133 |
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134 | // scratchpad[1]=0b00000010; // Testbytes for Temperatur calculation
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135 | // scratchpad[0]=0b01010001;
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136 | }
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137 | if((scratchpad[1]&0xF8)==0x00){ .
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138 | temp = (float)(((scratchpad[1]<<8)+scratchpad[0]));
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139 | temp *= 0.0625;
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140 |
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141 | }else{
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142 | uint8_t tmp;
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143 | tmp =scratchpad[0];
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144 | tmp= ~ tmp;
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145 | tmp= tmp >> 1;
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146 | temp = (-1)*(tmp+1);
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147 | if ((scratchpad[0]&0b00000001)==1){
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148 | temp=temp+0.5;
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149 | }
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150 |
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151 | }
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152 |
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153 | // temp=scratchpad[2]; // Return Scratchpad Byte X for Controll
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154 |
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155 | return temp;
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156 |
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157 | }
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158 | //-----------------------------------------
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159 | // Initialize DS18S20
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160 | //-----------------------------------------
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161 | uint8_t ds1820_init(uint8_t used_pin)
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162 | {
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163 | uint8_t error;
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164 | error=ds1820_reset(used_pin); //1. Reset
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165 | if (error==0){
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166 | ds1820_wr_byte(0xCC,used_pin); //2. skip ROM
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167 | ds1820_wr_byte(0x44,used_pin); //3. ask for temperature conversion
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168 | for (i = 0;i < 1000;i++){ //4. wait until conversion is finished
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169 | _delay_us(900);
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170 | }
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171 | error=ds1820_reset(used_pin); //5. Reset
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172 | ds1820_wr_byte(0xCC,used_pin); //6. skip ROM
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173 | ds1820_wr_byte(0xBE,used_pin); //7. Read entire scratchpad 9 bytes
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174 | }
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175 | return error;
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176 |
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177 | }
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