Calibration for analog sensor (voltage, resistance and NTC sensors)

Tips for UTCOMP's features and tutorials for assembling additional sensors in vehicles.
tmckeown
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Joined: Wed Jul 05, 2017 9:09 pm

Re: Calibration for analog sensor (voltage, resistance and NTC sensors)

Postby tmckeown » Thu Jul 06, 2017 11:23 am

ArT wrote:Is it connected only to UTCOMP AdcVccX ports?
Or is it connected also to other gauge?


I also have the original gauges at racecar dashboard, so it is connected to both

Timo

ArT
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Re: Calibration for analog sensor (voltage, resistance and NTC sensors)

Postby ArT » Thu Jul 06, 2017 12:14 pm

If it is connected to both that you can not operate on resistance - you will need voltage levels (because other gauge power supply it and translate resistance to voltage and translation depends on internal circuit in other gauge - you do not know this circuit).
It such case it should be connected to AdcX.

If you will connect it only to UTCOMP that resistance is enough and it should be connected to AdcVccX ports.

I calibrated temperature sensor based on resistance - when sensor is connected ONLY to AdcVccX in utcomp (and disconnected from other gauge), than R25 = 2037, Beta = 4251 and error <1C.
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For pressure sensor it should be first translated to bar:

250 ohms = 0psi = 0 bar
158 ohms = 25psi = 1,72 bar
111 ohms = 50psi = 3,45 bar
75 ohms = 75psi = 5,17 bar
43 ohm = 100 psi = 6,89 bar
and it seems that you have wrong measurements because it is not linear in whole range (and it should be):
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I can linearize in range of 2-7 bar but error will be about 0,2-0,3bar:
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in such case a = -10,44, b = 9,13
and again - sensor should be connected only to AdcVccX in utcomp (and disconnected from other devices)

If you would like to use the sensor on multiple gauges, than please share real voltage tables.
I'll help you to scale it 8-)

NealXu
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Joined: Wed Jan 03, 2018 6:34 pm

Re: Calibration for analog sensor (voltage, resistance and NTC sensors)

Postby NealXu » Wed Jan 03, 2018 6:39 pm

Hi...i am a new user here. For my fuel pressure sensor, it also is not connected to the ECU. It will be a 3-wire transducer that operates on 5V. It will output .5 to 4.5V for 0-150 PSI. I've read the tutorial and can use pin A18 to supply 5V. I take it I'll ground it to where pin A12 is grounded, and run the signal wire to Adc3 .

pcba board

Gims_90
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Joined: Mon Dec 31, 2018 11:56 am

Re: Calibration for analog sensor (voltage, resistance and NTC sensors)

Postby Gims_90 » Mon Dec 31, 2018 1:10 pm

Hello everyone, I need your advice. I have these ntc sensors to use in my utcomp pro but I only have this table so I do not know the ohms. they are sensors that have a range of 4 to 150 degrees celsius so I wanted to mount them. someone can help me calculate the parameters needed for calibration of my outcomp? I tried with the excel tables found on this guide, but I could not find the solution to my problem. this is what I know:





0-5V analog output scaling table

VOLTS--------TEMP (C°)
0,50 ------------4
0,75 ------------13
1,00 ------------22
1,25 ------------32
1,50 ------------41
1,75 ------------50
2,00 ------------59
2,25 ------------68
2,50 ------------77
2,75 ------------86
3,00 ------------95
3,25 ------------104
3,50 ------------113
3,75 ------------122
4,00 ------------131
4,25 ------------140
4,50 ------------149

0-5V analog output scaling formulas

TEMP (C°) = 36,09 * VOLTS - 13,61


Thank's so much :D :D

ArT
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Re: Calibration for analog sensor (voltage, resistance and NTC sensors)

Postby ArT » Mon Dec 31, 2018 4:34 pm

This is not NTC formula and it is not compatible with UTCOMP. You have linear formula. You can estimate it with NTC - please take a look at NTC(U) in excel - but it will be big error.
Try R25=223 and Beta=-2909 - in such case it is:
+/-3C for 0-60C range
+/- 1C for 60-120C range
+/-5C for 120-130C range
and huge error above 130C.


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