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jacho |
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#include "1wire.c" |
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// compute CRC |
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// *sn - pointer to the byte array |
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// num - length of array |
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inline int8 TM_check_CRC(unsigned int8 *sn, unsigned int8 num) |
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{ |
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// CRC table |
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const int8 TouchCRC[256]= { |
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0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65, |
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157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220, |
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35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98, |
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190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255, |
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70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7, |
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219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154, |
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101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36, |
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248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185, |
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140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205, |
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17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80, |
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175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238, |
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50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115, |
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202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139, |
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87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22, |
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233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168, |
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116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53}; |
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int8 CRC; |
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int8 i; |
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CRC=0; |
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for(i=0;i<num;i++) CRC=TouchCRC[CRC ^ *(sn+i)]; |
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return(CRC); |
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} |
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float ds1820_read() |
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{ |
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unsigned int1 ready=0; |
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int8 SN[10]; |
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unsigned int8 n; |
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float result; |
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onewire_reset(); |
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onewire_write(0xCC); |
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onewire_write(0x44); |
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for(n=0;n<200;n++) // wait until sensor is busy or timeout will be over |
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{ |
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ready = onewire_read(); |
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if(ready == TRUE) break; |
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delay_ms(1); |
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} |
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onewire_reset(); |
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onewire_write(0xCC); |
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onewire_write(0xBE); |
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for(n=0;n<9;n++) SN[n]=onewire_read(); |
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if ((SN[8]==TM_check_CRC(SN,8))&&(SN[7]==0x10)) // Check CRC and family code to prevent O's error |
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{ |
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result=make16(SN[1],SN[0]); |
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result=result*6+result/4; // 1bit = 0,0625gradC recalculate to 1/100gradC |
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} |
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else |
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{ |
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result=-27315; |
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} |
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return(result); |
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} |