Rev Author Line No. Line
1045 jacho 1 #include "1wire.c"
2  
3 // compute CRC
4 // *sn - pointer to the byte array
5 // num - length of array
6 inline int8 TM_check_CRC(unsigned int8 *sn, unsigned int8 num)
7 {
8 // CRC table
9 const int8 TouchCRC[256]= {
10 0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
11 157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220,
12 35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98,
13 190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
14 70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7,
15 219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154,
16 101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36,
17 248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185,
18 140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205,
19 17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80,
20 175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238,
21 50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115,
22 202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139,
23 87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22,
24 233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168,
25 116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53};
26  
27 int8 CRC;
28 int8 i;
29  
30 CRC=0;
31 for(i=0;i<num;i++) CRC=TouchCRC[CRC ^ *(sn+i)];
32 return(CRC);
33 }
34  
35  
36 float ds1820_read()
37 {
38 unsigned int1 ready=0;
39 int8 SN[10];
40 unsigned int8 n;
41 float result;
42  
43 onewire_reset();
44 onewire_write(0xCC);
45 onewire_write(0x44);
46  
47 for(n=0;n<200;n++) // wait until sensor is busy or timeout will be over
48 {
49 ready = onewire_read();
50 if(ready == TRUE) break;
51 delay_ms(1);
52 }
53  
54 onewire_reset();
55 onewire_write(0xCC);
56 onewire_write(0xBE);
57  
58 for(n=0;n<9;n++) SN[n]=onewire_read();
59 if ((SN[8]==TM_check_CRC(SN,8))&&(SN[7]==0x10)) // Check CRC and family code to prevent O's error
60 {
61 result=make16(SN[1],SN[0]);
62 result=result*6+result/4; // 1bit = 0,0625gradC recalculate to 1/100gradC
63 }
64 else
65 {
66 result=-27315;
67 }
68 return(result);
69 }