NTC thermistor component

[Bijumon]

Hi everyone, I tried to read the temperature using a 10K @ 25°C NTC sensor with flowcode thermistor component, and it worked well, but the temperature variation resolution was 0.4 °C. Is it possible to increase the resolution to 0.1 °C or more? 

[stefan.erni]

Hi Bijumon

I suspect this depends on your processor, or more precisely, on the AD converter in the processor.
If you are using an ESP32, sample the temperature 10x at small intervals, add all value and divide it by 10. This value is much better.
You can also take a look at your reference voltage on the RTC. This should be stable and without variations.
Another possibility is a test with a low impedance NTC. A 1KOhm NTC for example

It would be interesting if we could also use the component with an external AD converter. Flowcode has some good new AD components.

regards

Stefan

[Bijumon]

Hi Stefan,

I am testing it on an Arduino UNO, which has a 10-bit ADC, and the reading is as follows:.

Actual reading is 25.10 °C, 25.50 °C, 25.90°C,  26.10°C  etc. (0.40 resolution)

I am expecting like : 25.10°C, 25.20°C, 25.30°C, 25.40°C  etc. (0.10 resolution)

The required range is -25 °C to +125 °C.

Is there any way to get  more precise reading with the same setup?

Best Regards.

[LeighM]

For 0.1 resolution with 10 bit ADC you would need the ADC input voltage to swing between 0v and supply voltage.
The voltage at the potential divider of the thermistor and series resistor will not do this.

[stefan.erni]

Hi LeighM, Hi Bijumon

I assume the UNO R1-R3 have 10Bit
only the new Uno R4 has 14 bit but the board is not yet supported by Flowcode.

Arduino UNO R4 Minima: up to 14-bit ADC

ABX00080_datasheet-3303990.pdf

(4.25 MiB) Downloaded 143 times

NTC thermistor component I think it's a good and practical component

It would be good if you could also use it with another external AD converter or simply with a 16-bit variable instead of the AD converter from the CPU

regards
Stefan

[BenR]

Hello,

For the 10-bit ADC based device it may be possible to increase the resolution (for a certain temperature range) by adjusting the bias resistor and or the resistance of the thermistor. Note that the accuracy of a thermistor will not be brilliant and so having the resolution you're after may be somewhat meaningless.

If you want accurate temperature measurement it might be worth moving to a onewire based temperature sensor e.g. the DS18B20. You will still only get 0.5°C resolution but it will be a lot more accurate then a thermistor will be and the 0.5°C increments will be consistent throughout the entire temperature range.

If you need more resolution as well as accuracy then the MAX31855/31856 IC will give you higher accurancy by using a thermocouple instead of thermistor.

I beleive the SHT31 sensor may also have 0.1°C resolution with no external components so this could be an option.

Supporting the R4 Uno would be fantastic, unfortunatley it's no easy feat as it's a whole new toolchain and code abstraction layer (CAL).

[medelec35]

Hi.
We also support AHT10, which has a resolution of 0.01C and you can purchase modules very cheaply that can run off 5V
As a bonus, it will also display humidity.

[Bijumon]

Hi all,

This method is giving me more accurate reading and good resolution, tested range is only form +2°C to +45°C.

Thread got from - https://curiousscientist.tech/blog/ntc- ... 32-arduino

B parameter calculator - https://www.thinksrs.com/downloads/prog ... lator.html

Best Regards.