Arduino: 1023 or 1024

We have a thermistor connected to an Arduino through a voltage divider circuit. The voltage divider consists of the thermistor and a second fixed resistor.

There are two circuit configurations:

1. the thermistor is connected to VCC
2. the thermistor is connected to GND

The table below presents the measurements taken at the Arduino pin. Each row represents the average value of 1,000 measurements. The first column contains the measurements when the thermistor is connected to VCC, the second column contains the measurements when the thermistor is connected to GND, and the third column contains the sum of the measurements.

At the end of the table, the average values for each column are presented, along with the rounded values.

  VCC     GND     SUM
-----------------------
560.46  463.19  1023.65
560.53  463.17  1023.70
560.54  463.14  1023.68
560.58  463.12  1023.70
560.58  463.09  1023.67
560.62  463.07  1023.69
560.59  463.06  1023.65
560.59  463.07  1023.66
560.63  463.05  1023.68
560.59  463.05  1023.64
560.59  463.04  1023.63
560.59  463.03  1023.62
560.55  463.01  1023.56
560.54  463.00  1023.54
560.51  462.99  1023.50
-----------------------
       Average
-----------------------
560.57	463.07	1023.64
-----------------------
        Round
-----------------------
561     463     1024   

As you can see, we need to use either the value 1023.5 or the rounded value 1024.

So, where should you connect the thermistor: to the VCC or GND?

The answer is: whatever you want, but consider it in your calculation formula. (see: https://asilichenko.blogspot.com/2024/06/calibrating-a-thermistor-for-arduino-projects.html

ADC Raw values voltage dependence

V(A pin)   ADC
--------------
   6     0,000
  15     1,000
  24     3,000
  20     2,000
  18     1,990
  32     4,974
  61    10,900
 113    21,754
 178    34,992
 270    53,988
 386    77,983
 517   105,000
 665   135,262
 789   160,959
 957   195,530
1050   214,722
1186   242,383
1346   275,648
1515   310,270
1728   354,011
1959   401,755
2128   436,242
2282   467,757
2452   502,255
2642   541,250
2842   582,145
3050   624,669
3219   659,189
3404   696,830
3584   733,497
3791   775,976
3960   810,705
4136   846,849
4296   879,643
4457   912,685
4623   947,387
4744   971,713
4892  1002,146
4960  1015,871
4995  1022,766
4999  1022,990
5000  1022,997