Thermistor calibration

Hi,
I use Sprinter, the active table is:
#if (THERMISTORHEATER == 1) || (THERMISTORBED == 1) //100k bed thermistor


#define NUMTEMPS_1 61
const short temptable_1[NUMTEMPS_1][2] = {
{ 23 , 300 },
{ 25 , 295 },
{ 27 , 290 },
{ 28 , 285 },
{ 31 , 280 },
{ 33 , 275 },
{ 35 , 270 },
{ 38 , 265 },
{ 41 , 260 },
{ 44 , 255 },
{ 48 , 250 },
{ 52 , 245 },
{ 56 , 240 },
{ 61 , 235 },
{ 66 , 230 },
{ 71 , 225 },
{ 78 , 220 },
{ 84 , 215 },
{ 92 , 210 },
{ 100 , 205 },
{ 109 , 200 },
{ 120 , 195 },
{ 131 , 190 },
{ 143 , 185 },
{ 156 , 180 },
{ 171 , 175 },
{ 187 , 170 },
{ 205 , 165 },
{ 224 , 160 },
{ 245 , 155 },
{ 268 , 150 },
{ 293 , 145 },
{ 320 , 140 },
{ 348 , 135 },
{ 379 , 130 },
{ 411 , 125 },
{ 445 , 120 },
{ 480 , 115 },
{ 516 , 110 },
{ 553 , 105 },
{ 591 , 100 },
{ 628 , 95 },
{ 665 , 90 },
{ 702 , 85 },
{ 737 , 80 },
{ 770 , 75 },
{ 801 , 70 },
{ 830 , 65 },
{ 857 , 60 },
{ 881 , 55 },
{ 903 , 50 },
{ 922 , 45 },
{ 939 , 40 },
{ 954 , 35 },
{ 966 , 30 },
{ 977 , 25 },
{ 985 , 20 },
{ 993 , 15 },
{ 999 , 10 },
{ 1004 , 5 },
{ 1008 , 0 } //safety
};
#endif

Now, when I test thermistor's resistance at 25 C, it reads 102K. Could someone kindly point me at the corresponding line in thetable?
Am I correct, this is Temp. vs. Resistance? But if so, 25 C corresponds to 295, so much for 100K thermistor?

Thank you.

Edited 1 time(s). Last edit at 04/30/2015 02:34AM by Fizpok.

0 degrees is at the bottom of the table. Temp is the second value, not the first.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Then 25 degrees - 987 (Ohm, kOhm?), and the thermistor is not 100K ?

It's a lookup table, so the lookup value is 987 and the temp is 25. The lookup value is calculated from the resistance table datasheet for a given thermistor. The calculated vales are something Sprinter can compare against the reading it takes from the analogue pin the thermistor is plugged in to. If you're interested in more detail, there's a spreadsheet on thingiverse that can generate a lookup table based on data about a thermistor - don't use the results it generates if you know specifically which thermistor you have, as the tables in Sprinter tend to be more accurate.

Chances are you have a 100K thermistor, as the reading is close enough and your ambient temperature reading is bound to be off the mark.

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[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

Thank you.